Pharmacological Principles & Herbal Supplements

Every drug you will ever give is a bargain. You accept a wanted effect and you accept, in the same breath, the unwanted ones that ride along with it. Pharmacology is the study of that bargain — what the body does to a drug, what the drug does to the body, and how a nurse tips the odds toward benefit and away from harm. This chapter builds the vocabulary and the reasoning you will use for every medication in the rest of the book: how drugs are named and grouped, how they move through a patient, how they act once they arrive, how to give them safely, and why the bottle of ginkgo in your patient's purse belongs on the medication list too.

Section 1Drugs, names & classes

One drug, three names

A drug is any chemical that changes the way the body works. Every approved drug carries three names, and confusing them is one of the quiet sources of medication error. The chemical name describes the molecule — N-acetyl-para-aminophenol — and you will essentially never use it. The generic name (also called the nonproprietary or United States Adopted Name) is the drug's one true name: acetaminophen. It belongs to no company, it never changes, and it is what the order, the chart, and the reference book use. The trade name (brand or proprietary name) is the marketing name the manufacturer owns — Tylenol, and a dozen others.

Here is why this matters at the bedside. One generic drug can wear many trade names, and a patient arriving from home may know only the brand. A patient taking Tylenol, Percocet, and a nighttime cold remedy is taking acetaminophen three times and may sail past the maximum daily dose without ever recognizing the drug. Nurses work in generic names precisely because the generic name is the only name that cannot hide a duplicate.

Generic names also carry built-in clues. Most classes share a stem — a fragment of the name that tells you what the drug is before you look it up. If it ends in -olol it is a beta blocker; -pril, an ACE inhibitor; -statin, an HMG-CoA reductase inhibitor; -prazole, a proton pump inhibitor; -cillin, a penicillin; -sartan, an angiotensin II receptor blocker. Learning stems is one of the highest-yield hours you can spend in this book.

Classes: sorting drugs by what they do

A drug class (or pharmacologic class) is a group of drugs that share a mechanism of action, and therefore share effects, adverse effects, and nursing implications. This is the whole reason pharmacology is learnable. There are thousands of drugs and only a few dozen mechanisms that matter. You are not memorizing a list; you are learning a small number of stories and then recognizing which story a new drug belongs to.

Drugs can be grouped two ways, and both appear in practice. A therapeutic classification says what the drug is used for — antihypertensive, anticoagulant, analgesic. A pharmacologic classification says how it works — calcium channel blocker, vitamin K antagonist, opioid receptor agonist. One drug lives in both systems at once: metoprolol is therapeutically an antihypertensive and antianginal, and pharmacologically a beta₁-selective adrenergic blocker.

Prototype drugs

Because a class shares a mechanism, each class has a prototype — the well-studied, representative member you learn cold, then use as the template for every other drug in the family. Learn morphine and you have most of hydromorphone, fentanyl, and oxycodone. Learn furosemide and bumetanide and torsemide hold few surprises. When you meet an unfamiliar drug, your first question is not "what does this do?" but "what class is this, and what is the prototype?"

Section 2Pharmacokinetics — what the body does to the drug

The four-step journey

Pharmacokinetics is the study of drug movement: how a drug gets in, where it goes, how it is chemically changed, and how it leaves. Four processes, remembered as ADME, run at once from the moment of administration: Absorption, Distribution, Metabolism, Excretion. Everything that determines how much drug reaches its target and for how long lives in these four steps — which is why the same 5 mg tablet behaves very differently in a young athlete and in an 88-year-old with heart failure and kidney disease.

Absorption is the movement of drug from the site of administration into the bloodstream. It depends on the route (IV is instant and complete; oral is slow and partial), on blood flow to the site (a shocked patient absorbs almost nothing from an intramuscular injection), on the drug's ability to cross membranes (lipid-soluble and un-ionized crosses easily), and on the presence of food. The fraction of a dose that actually reaches the systemic circulation intact is its bioavailability. By definition an IV dose is 100% bioavailable; an oral dose is always less.

Distribution is the drug's travel from blood into tissue. Blood flow decides who gets it first — heart, brain, liver, and kidney are perfused richly; fat and resting muscle far less. Two barriers matter clinically: the blood–brain barrier, which only lipid-soluble drugs cross easily (a reason some antihistamines sedate and others do not), and the placenta, which stops almost nothing. Distribution is also governed by protein binding: many drugs ride on albumin, and only the unbound (free) fraction is active. A patient with low albumin — malnourished, cirrhotic, elderly — has more free drug from the same dose and is at risk for toxicity at a "normal" dose.

Metabolism and the first-pass effect

Metabolism (biotransformation) chemically alters a drug, usually in the liver, usually via the cytochrome P450 (CYP450) enzyme family. Most of the time metabolism inactivates the drug and makes it water-soluble enough to be excreted. Sometimes it does the opposite: a prodrug is given inactive and must be metabolized to work — codeine must be converted to morphine by CYP2D6, and a patient who is a poor metabolizer gets little relief while an ultrarapid metabolizer can be dangerously overdosed.

The CYP450 system is where most drug–drug interactions live. An enzyme inducer (rifampin, phenytoin, carbamazepine, St. John's wort) speeds metabolism, so partner drugs fall to subtherapeutic levels — the classic disaster is an oral contraceptive or warfarin failing. An enzyme inhibitor (many azole antifungals, clarithromycin, amiodarone, grapefruit juice) slows metabolism, so partner drug levels climb toward toxicity.

The first-pass effect is the reason a route change is never a straight swap. Anything absorbed from the stomach or intestine drains into the portal vein and is carried through the liver before it reaches the rest of the body. The liver may destroy most of the dose on that first trip. Oral morphine is the textbook case: roughly three times the IV dose is needed by mouth for the same effect. Routes that bypass the portal circulation — IV, sublingual, transdermal, rectal (partially), inhaled — escape the first pass, which is exactly why nitroglycerin is placed under the tongue and not swallowed.

Excretion, half-life, and steady state

Excretion removes the drug, overwhelmingly through the kidneys. Reduced renal function — from age, dehydration, or kidney disease — means drug accumulates, so renally cleared drugs are dose-adjusted to creatinine clearance or eGFR. Smaller routes matter for specific drugs: bile and feces (some antibiotics), lungs (inhaled anesthetics), and breast milk, which is trivial in quantity but never trivial for the nursing infant.

The single most useful number in kinetics is the half-life (t½): the time for plasma concentration to fall by half. Half-life sets the dosing interval, and it drives two rules worth memorizing. It takes about four to five half-lives to reach steady state — the plateau where the amount going in equals the amount coming out, and where the drug is finally doing its full job. It also takes about four to five half-lives to clear a drug after the last dose. That is why a loading dose exists: when a patient cannot wait days for steady state, a large first dose fills the tank immediately, and smaller maintenance doses keep it there.

Section 3Pharmacodynamics — what the drug does to the body

Receptors: the lock and the key

Pharmacodynamics is the other half of the story: once the drug arrives, what does it actually do? Almost always, it binds something. Most drugs act on a receptor — a protein, usually on a cell membrane, that the body built for its own signaling molecule. Drugs do not invent new functions. They borrow existing ones, turning the body's own switches up or down. Albuterol works because your lungs already have beta₂ receptors waiting for epinephrine; morphine works because your nervous system already has mu receptors waiting for endorphins.

Two properties describe the fit. Affinity is how tightly a drug binds its receptor. Intrinsic activity is whether binding actually triggers a response. That pair generates the entire vocabulary below — and it explains selectivity, too. A drug is called selective when it prefers one receptor subtype, but selectivity is dose-dependent and never absolute: metoprolol is beta₁-selective at ordinary doses, which is why it is the safer choice if a patient with asthma must take a beta blocker at all, but at higher doses it spills onto the beta₂ receptors in the airway and can trigger bronchospasm anyway. Nonselective agents such as propranolol block beta₂ from the first dose and are avoided in reactive airway disease.

Agonists, antagonists, and everything between

An agonist binds and activates — it mimics the body's own messenger and turns the response on. An antagonist binds and blocks — it has affinity but no intrinsic activity, so it occupies the receptor and prevents the natural messenger (or another drug) from acting. Antagonists have no effect of their own; their entire effect is the absence of someone else's. A partial agonist binds and activates only weakly, producing a submaximal response no matter how high the dose — a ceiling that can be a safety feature.

Dose–response, potency, efficacy, and the therapeutic index

Plot dose against effect and you get the dose–response curve: little happens at the bottom (below threshold), the response rises steeply through the useful middle, then flattens into a plateau where the receptors are saturated and more drug buys no more effect — only more toxicity. That plateau is why "the pain is still there, give more" eventually stops being pharmacology and starts being harm.

Two words students routinely swap. Potency is how much drug it takes to produce a given effect — a more potent drug works at a smaller dose. Efficacy is the maximum effect the drug can produce, no matter the dose. Efficacy is what you want; potency is only a milligram number. Hydromorphone is more potent than morphine (fewer milligrams needed) but not more efficacious. Meanwhile ibuprofen has a hard analgesic ceiling that no dose can escape: for severe pain, an opioid's greater efficacy is the point.

The therapeutic index (TI) compares the dose that poisons to the dose that helps — TD₅₀/ED₅₀, the dose toxic to half the population divided by the dose effective in half of it. A high TI means a wide, forgiving margin. A low (narrow) therapeutic index means the effective dose and the toxic dose are uncomfortably close, and these are the drugs that get serum levels drawn, get double-checked, and land patients in the ED. Learn the list: warfarin, digoxin, lithium, phenytoin, levothyroxine, theophylline, carbamazepine, vancomycin, aminoglycosides (gentamicin), and insulin. The therapeutic range is the concentration window between "not working" and "poisoning" — and for these drugs, that window is a canyon you can fall out of in either direction.

Section 4Safe medication administration

The rights of medication administration

Everything above is theory until you are standing at a bedside with a cup in your hand. The rights of medication administration are the checklist that turns knowledge into safety. The traditional five are right patient, right drug, right dose, right route, right time, and most programs and employers add several more: right documentation, right reason (indication), right response, right to refuse, and right education. Verify them at three points — when you pull the medication, when you prepare it, and again at the bedside before it goes in.

Two of these deserve emphasis because they are the ones most often skipped. Right patient means two identifiers — name and date of birth against the armband, never the room number, and never the patient's nod when you say the wrong name aloud. Right response means the job is not finished when the drug is given: you gave metoprolol, so you recheck the heart rate; you gave morphine, so you reassess pain and respiratory rate and sedation; you gave insulin, so you know when the glucose will bottom out. Documentation comes after administration, never before — charting a drug you have not yet given is how a dose gets given twice.

Routes

The route decides speed, completeness, and reversibility. The single most important safety principle in the table below is this: once it is in, you cannot take it back, and the faster the route, the more absolutely that is true. An oral overdose can sometimes be intercepted; an IV push cannot.

Orders and error prevention

A complete medication order names the patient, the date and time, the drug, the dose, the route, the frequency, and the prescriber's signature. If any element is missing, ambiguous, or simply does not make sense for this patient, the order is not valid and you do not give it — you clarify it. "The prescriber wrote it" has never been a defense; the nurse who administers is independently accountable for the drug.

High-alert medications are those that cause disproportionate harm when they go wrong: insulin, anticoagulants (heparin, warfarin), opioids, concentrated electrolytes (especially potassium chloride), chemotherapy, neuromuscular blockers, and sedatives. They earn an independent double-check — a second nurse who verifies the drug, dose, pump settings, and patient without being told what you already calculated. And a permanent rule: concentrated potassium chloride is never given IV push, ever. It must be diluted and infused.

Then there is how the numbers are written. Use a leading zero (0.5 mg, not .5 mg — a missed decimal point becomes a tenfold overdose) and never a trailing zero (5 mg, not 5.0 mg — which reads as 50). Spell out "units" rather than writing "U," which is misread as a zero. Avoid the abbreviations on your facility's do-not-use list. And know your look-alike/sound-alike (LASA) pairs: hydralazine and hydroxyzine, celecoxib and citalopram, metformin and metronidazole, lamotrigine and lamivudine, and — the pair that reaches the ICU — morphine and hydromorphone. Read the label three times — pulling it, preparing it, and returning or discarding it.

Section 5Herbal supplements & interactions

Supplements are drugs, whatever the label says

Roughly one in five adults takes an herbal product, and the majority never mention it to a clinician — because in their minds a supplement is food, not medicine. That belief is the hazard. A dietary supplement in the United States is regulated under the Dietary Supplement Health and Education Act (DSHEA) of 1994 as a food, not a drug. It requires no pre-market proof of safety or efficacy, and the FDA can act only after harm appears. Nobody verified the potency, the purity, or the contents of the bottle in your patient's bag.

Meanwhile, the pharmacology is entirely real. Digoxin comes from foxglove, aspirin from willow bark, morphine from the poppy, atropine from belladonna, and paclitaxel from the yew tree. Plants are chemists. "Natural" has never meant safe — hemlock is natural — and a compound potent enough to help is by definition potent enough to interact.

The interactions that actually matter

Herbal interactions cluster into three predictable mechanisms, which means you can reason instead of memorize. First, CYP450 and P-glycoprotein effects: St. John's wort is a powerful inducer and can wreck a drug regimen by driving levels down. Second, bleeding risk: the products with antiplatelet activity stack on top of anticoagulants, antiplatelets, and NSAIDs — the memorable cluster is the four G's plus feverfew (garlic, ginger, ginkgo, ginseng, feverfew). Third, additive pharmacology: kava and valerian pile onto CNS depressants; ginseng pushes glucose down on top of antidiabetics.

How to ask

The interview technique changes the answer. "Are you taking any medications?" reliably gets a "no" from a patient with three supplement bottles at home, because they do not classify them as medications. Ask instead: "What do you take that you buy without a prescription — vitamins, herbs, teas, powders, protein shakes, anything from the health-food aisle, anything a family member recommends?" Then ask them to bring in the actual bottles. Document each one on the medication list. And teach without judgment: the goal is not to talk the patient out of a supplement, it is to keep them from a bleed, a rejected transplant, or a serotonin crisis they never saw coming. Two teaching points earn their place in nearly every discharge: tell every prescriber about every supplement, and stop most herbal products one to two weeks before surgery.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Absorption

Movement of a drug from its administration site into the bloodstream; the first step of pharmacokinetics.

Adverse drug reaction (ADR)

A harmful, unintended response to a drug given at a normal dose; broader and more serious than a predictable side effect.

Agonist

A drug that binds a receptor and activates it, mimicking the body's own messenger.

Antagonist

A drug that binds a receptor and blocks it, producing no effect of its own; the mechanism behind antidotes such as naloxone.

Bioavailability

The fraction of an administered dose that reaches the systemic circulation intact; 100% for IV, always less for oral.

Distribution

Movement of a drug from the blood into tissues; shaped by perfusion, protein binding, and barriers such as the blood–brain barrier and placenta.

Efficacy

The maximum effect a drug can produce regardless of dose — what the drug is capable of.

Excretion

Removal of drug and metabolites from the body, chiefly by the kidneys.

First-pass effect

Metabolism of an orally absorbed drug by the liver before it reaches systemic circulation; bypassed by IV, sublingual, and transdermal routes.

Half-life (t½)

The time required for plasma drug concentration to fall by 50%; sets the dosing interval and predicts steady state and clearance.

High-alert medication

A drug that causes disproportionate harm when used in error — insulin, anticoagulants, opioids, concentrated electrolytes, chemotherapy — warranting an independent double-check.

Loading dose

A large initial dose given to reach a therapeutic concentration quickly, rather than waiting four to five half-lives.

Metabolism (biotransformation)

Chemical alteration of a drug, mostly by hepatic CYP450 enzymes; usually inactivates the drug, but activates a prodrug.

Pharmacodynamics

What the drug does to the body — receptor binding, mechanism of action, and the dose–response relationship.

Pharmacokinetics

What the body does to the drug — absorption, distribution, metabolism, and excretion.

Potency

The amount of drug required to produce a given effect; a more potent drug works at a lower dose. Not the same as efficacy.

Prodrug

An inactive drug that must be metabolized into its active form — codeine converted to morphine, for example.

Prototype drug

The representative, well-studied member of a class used as the template for the rest of the family.

Side effect

A predictable, dose-related effect other than the intended one; often tolerable, sometimes the reason a patient quits the drug.

Steady state

The plateau at which drug entering the body equals drug leaving it; reached after roughly four to five half-lives of regular dosing.

Therapeutic index

The ratio of the toxic dose to the effective dose; a low (narrow) index means a dangerously small margin for error.

Trough level

The lowest drug concentration in a dosing interval, drawn about 30 minutes before the next dose; the level that reveals accumulation.

Antimicrobial Drugs

Antimicrobials are the only drugs we give that are aimed at something that is not the patient. Everything else in the medication room — the beta blocker, the insulin, the opioid — changes the person in the bed. An antibiotic is meant to kill an invader while leaving that person untouched, and how well it manages that trick is the difference between a cure and a kidney injury. This chapter walks through how these drugs pick their target, how they are grouped by the machinery they break, why the microbes are learning to shrug them off, and what the nurse does at the bedside to make the whole thing work safely. Learn the classes as families and the details stop being memorization — they start being predictions you can make.

Section 1Principles of antimicrobial therapy

Selective toxicity: the whole game

Selective toxicity is the principle that makes antimicrobial therapy possible: the drug attacks a structure the microbe has and the patient does not. Bacteria build a peptidoglycan cell wall; your cells build no wall at all, so a drug that sabotages wall construction is nearly invisible to you. Bacteria run 70S ribosomes assembled from 30S and 50S subunits; your cells run 80S ribosomes, so a drug shaped to jam the bacterial one mostly ignores yours. Bacteria have to synthesize their own folate from scratch; you eat yours, so a drug that blocks the synthesis pathway starves the bacterium and skips you entirely.

Read that list backwards and you have predicted the side effects. Selective toxicity is never perfect. Human mitochondria carry ribosomes that resemble bacterial ones — which is exactly why linezolid suppresses bone marrow and why aminoglycosides damage the hair cells of the inner ear. The narrower the gap between microbe and host, the more toxic the drug. That is the single sentence that explains why penicillin is safe enough to give a toddler and amphotericin B has a nickname involving rigors.

Spectrum, and cidal versus static

Narrow-spectrum drugs hit a limited range of organisms; broad-spectrum drugs hit many. Students often assume broad is better. It is not. Broad-spectrum therapy clear-cuts the patient's normal flora along with the pathogen, opening the door to superinfection — Clostridioides difficile colitis, Candida thrush, vaginal yeast — and it applies selection pressure across a far wider bacterial population. Broad is a starting guess, not a goal. The goal is always the narrowest drug that covers the actual organism.

Bactericidal drugs kill outright (beta-lactams, aminoglycosides, fluoroquinolones, vancomycin, metronidazole). Bacteriostatic drugs stall replication and let the immune system finish the job (tetracyclines, macrolides, clindamycin, sulfonamides, linezolid). The distinction matters most when the immune system cannot help — endocarditis, meningitis, neutropenia — where a cidal drug is generally required.

Culture and sensitivity, and the empiric window

A culture and sensitivity (C&S) has two halves. The culture identifies the organism. The sensitivity panel exposes it to a series of drugs and reports the minimum inhibitory concentration (MIC) — the lowest concentration that stops growth — then labels each drug susceptible, intermediate, or resistant. A low MIC number alone does not mean "best drug"; the interpretation next to it does, because it factors in what concentration the drug actually reaches at the site of infection.

Cultures take 24 to 72 hours. A septic patient does not have 72 hours. So we start empiric therapy — an educated, broad guess based on the suspected site, the likely organisms for that site, the local antibiogram, and the patient's recent exposures. Then, when the C&S returns, therapy is de-escalated to a narrow drug that the organism is actually susceptible to. Empiric therapy is a bridge, not a destination, and a broad antibiotic still running on day five with a susceptibility report on the chart is a stewardship failure.

Section 2Antibiotics by mechanism

Cell wall inhibitors: break the box

Bacteria live under enormous internal osmotic pressure and are held together by a peptidoglycan mesh. Interrupt the cross-linking and the cell swells and bursts. All of these drugs are therefore bactericidal, and because human cells have no wall, the beta-lactams are among the safest antimicrobials we own. That mechanism-based safety belongs to the beta-lactams, not to the whole wall-active group: vancomycin attacks wall synthesis too but is nephrotoxic and ototoxic and needs trough/AUC levels with serial creatinine, and daptomycin needs weekly CPK.

The beta-lactams — named for the four-membered beta-lactam ring they share — include penicillins, cephalosporins, carbapenems, and the monobactam aztreonam. They bind the penicillin-binding proteins that do the cross-linking. Penicillins run from narrow (penicillin G, for strep and syphilis) to broader (amoxicillin, ampicillin) to antipseudomonal (piperacillin-tazobactam). Cephalosporins climb through generations — cefazolin (first, the classic surgical prophylaxis drug), ceftriaxone (third, meningitis and pneumonia), cefepime (fourth, Pseudomonas), ceftaroline (fifth, active against MRSA). Carbapenems (meropenem, ertapenem, imipenem-cilastatin) are the heavy artillery reserved for resistant gram-negatives. Aztreonam covers gram-negatives only and is the escape hatch for a patient with true penicillin anaphylaxis.

The non-beta-lactam wall drugs matter too. Vancomycin, a glycopeptide, blocks wall building at a different step and is a workhorse for MRSA. Daptomycin is a lipopeptide that punches holes in the gram-positive membrane rather than the wall; it is inactivated by lung surfactant, so it is never the answer for pneumonia.

Protein synthesis inhibitors: jam the ribosome

The bacterial 70S ribosome is a target with two halves, and the drugs sort by which half they grab. Hitting the 30S subunit: aminoglycosides (gentamicin, tobramycin, amikacin) and tetracyclines (doxycycline, minocycline). Hitting the 50S subunit: macrolides (azithromycin, erythromycin, clarithromycin), clindamycin, linezolid, and chloramphenicol. A useful mnemonic: "buy AT 30, CELL at 50" — Aminoglycosides and Tetracyclines at 30S; Chloramphenicol, Erythromycin/macrolides, Lincosamides (clindamycin), and Linezolid at 50S.

This is where selective toxicity gets thin, and the toxicities are the reason. Aminoglycosides are nephrotoxic and ototoxic — the hearing loss can be permanent — so they demand peak and trough levels and daily creatinine. Tetracyclines chelate calcium: prolonged or repeated courses stain developing teeth, so avoid them under age 8 and in pregnancy — with one exception that matters enormously, because doxycycline is first-line at any age for suspected tick-borne rickettsial illness (Rocky Mountain spotted fever, ehrlichiosis, anaplasmosis), where a short course (under 21 days) does not cause clinically significant staining and withholding the drug can be fatal. They are also inactivated if the patient swallows them with milk, antacids, or an iron pill. Macrolides prolong the QT interval. Clindamycin is the classic C. difficile offender. Linezolid, working on a ribosome that looks like the one in your mitochondria, causes thrombocytopenia, optic and peripheral neuropathy, and — because it is a weak MAO inhibitor — serotonin syndrome when stacked on an SSRI.

Nucleic acid and metabolic inhibitors: break the blueprint, starve the factory

Fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin) poison DNA gyrase and topoisomerase IV, the enzymes that untangle bacterial DNA. They are potent, oral, and carry more boxed warnings than almost anything else on the shelf: tendinitis and tendon rupture (Achilles, worse over 60, on steroids, or post-transplant), aortic aneurysm and dissection, peripheral neuropathy, CNS effects, QT prolongation, and blood glucose swings. Rifampin blocks bacterial RNA polymerase, turns urine, sweat, and tears orange (stains contact lenses), is hepatotoxic, and is a ferocious CYP450 inducer that can quietly defeat oral contraceptives and warfarin. Metronidazole is activated inside anaerobes and protozoa where it shreds DNA; it produces a metallic taste and a disulfiram-like reaction with alcohol.

The metabolic inhibitors starve the bacterium of folate. Sulfamethoxazole blocks dihydropteroate synthase and trimethoprim blocks dihydrofolate reductase — two sequential steps in one pathway, which is why the combination (TMP-SMX) is synergistic and bactericidal. Watch for rash that could become Stevens-Johnson syndrome, hyperkalemia, crystalluria (push fluids), photosensitivity, and a sharp rise in the INR of anyone on warfarin. That same folate mechanism closes a loop in pregnancy: because trimethoprim antagonizes folate, TMP-SMX is avoided in the first trimester (neural tube and other structural defects — folic acid supplementation is advised if it must be used) and again at term, where the sulfonamide displaces bilirubin and risks kernicterus in the newborn. Isoniazid, a first-line TB drug, blocks mycolic acid synthesis and causes peripheral neuropathy — which is why it is co-prescribed with pyridoxine (vitamin B6) — and hepatitis.

Section 3Resistance and stewardship

How resistance arises

Antibiotics do not create resistance. They select for it. In any large bacterial population a few cells already carry a gene that happens to blunt the drug — through random mutation, or borrowed wholesale from a neighbor. Give the antibiotic and you kill the susceptible majority, which is exactly the outcome you wanted, but you also hand the survivors an empty room with no competition. They multiply. This is ordinary natural selection running at bacterial speed, and every unnecessary dose accelerates it.

Bacteria are also promiscuous with DNA. Horizontal gene transfer lets a resistance gene jump between organisms that are not even related: conjugation passes a plasmid through a direct bridge, transformation scoops up free DNA from a dead cell, and transduction ferries genes by bacteriophage. One gut organism can donate a resistance plasmid to a passing pathogen overnight.

The mechanisms themselves come in four shapes, and you can read them straight off the resistance figure. Enzymatic inactivation — beta-lactamases chew open the beta-lactam ring; extended-spectrum beta-lactamases (ESBLs) chew a wider menu; carbapenemases chew even carbapenems. Target modification — MRSA's mecA gene builds an altered penicillin-binding protein (PBP2a) that ordinary beta-lactams cannot grip; VRE's vanA gene rebuilds the wall precursor so that its terminal D-alanine-D-alanine becomes D-alanine-D-lactate, which vancomycin can no longer bind. Efflux pumps bail the drug back out before it works. Reduced permeability shuts the porin doors so the drug never gets in.

The organisms you will meet

MRSA is Staphylococcus aureus that has become immune to the entire traditional beta-lactam class at once — not just methicillin — because PBP2a ignores penicillins, cephalosporins, and carbapenems alike. That single gene knocks out the safest, cheapest drugs you had and forces a move to vancomycin, linezolid, daptomycin, or ceftaroline — the one beta-lactam specifically engineered to bind PBP2a anyway. VRE pushes further, defeating the drug we reached for when MRSA appeared. ESBL-producing gram-negatives push therapy toward carbapenems; CRE defeat the carbapenems and leave a genuinely thin bench. And C. difficile, while not a resistance mechanism itself, is the price of collateral damage: the antibiotic wipes out the gut community and C. diff blooms in the vacancy.

Stewardship and the nurse

Antimicrobial stewardship is the coordinated effort to use these drugs only when needed, and then in the right drug, dose, route, and duration. It is often described as a pharmacy-and-physician program, which badly understates the nurse's role — the nurse is the person who actually gets the culture, notices the report, gives the dose, and hears the patient's story.

Concretely: get the cultures before the first dose. Take a real allergy history — "penicillin gave me an upset stomach at age six" is not an allergy, and roughly 9 in 10 people labeled penicillin-allergic are not, so that label costs them broader, more toxic, more expensive drugs for decades. Flag day 3: is the culture back, and is the patient still on the broad empiric drug? Push the IV-to-PO switch when the patient is eating and stable (linezolid, fluoroquinolones, metronidazole, doxycycline, and fluconazole are all essentially fully absorbed orally). Question the duration — evidence keeps shortening courses. Teach the patient that antibiotics do nothing for a cold, that leftovers are not to be saved or shared, and that the prescribed course should be taken as directed rather than stopped the moment they feel better. And do the unglamorous thing that prevents more resistant infections than any drug decision: wash your hands.

Section 4Antifungals and antivirals

Antifungals: a much smaller gap

Fungi are eukaryotes. Their cells are built like yours — nucleus, 80S ribosomes, similar membranes — which means the pool of microbe-only targets is small and antifungal drugs are, as a group, markedly more toxic than antibacterials. Almost every antifungal exploits one of two genuine differences: fungal membranes use ergosterol where yours uses cholesterol, and fungal cell walls contain beta-(1,3)-D-glucan, which you do not make at all.

Amphotericin B (a polyene) binds ergosterol directly and rips pores in the membrane. It is powerful, and it is rough: infusion-related fevers, rigors, and shaking chills earned it the nickname "shake and bake," plus dose-limiting nephrotoxicity with potassium and magnesium wasting. Liposomal formulations are considerably gentler — and this is a genuine safety trap, because the conventional and liposomal doses are very different and are not interchangeable. Verify the formulation on the label against the order. The azoles (fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole) block lanosterol 14-alpha-demethylase, the enzyme that makes ergosterol; they are the mainstay of oral therapy but bring hepatotoxicity, QT prolongation, and heavy CYP450 interactions with warfarin and statins. Voriconazole adds a distinctive transient visual disturbance — blurred or bright-tinged vision — and photosensitivity. The echinocandins (caspofungin, micafungin, anidulafungin) attack the beta-glucan wall, a target humans simply do not have, and are correspondingly well tolerated; they are first-line for invasive candidemia but are IV-only. Terbinafine treats nail and skin fungus over long courses — monitor liver function and warn about taste changes. Nystatin is topical: swish and swallow for thrush, and teach the patient to hold it in the mouth before swallowing.

Antivirals: the narrowest gap of all

A virus replicates using your cellular machinery, so there is almost nothing to attack that is not also yours. Antivirals work by targeting the handful of enzymes the virus brings itself — a viral polymerase, a protease, an integrase, a neuraminidase. They also suppress rather than cure most of the time, and they are time-sensitive: the earlier the start, the more the drug can do — though in severe or high-risk illness a late start is still worth making.

Acyclovir and its better-absorbed prodrug valacyclovir treat herpes simplex and varicella-zoster. The elegance is in the activation: acyclovir must be phosphorylated by viral thymidine kinase before it works, so it is essentially inert in an uninfected cell. IV acyclovir crystallizes in renal tubules, so hydrate the patient well and infuse over at least an hour. Ganciclovir and valganciclovir handle CMV and are bone-marrow suppressive. Oseltamivir blocks influenza neuraminidase and gives its greatest benefit when started within about 48 hours of symptom onset in uncomplicated outpatient flu; hospitalized, severe, progressive, or high-risk patients are treated no matter how long symptoms have lasted. For HIV, antiretroviral therapy combines drug classes — NRTIs (tenofovir, emtricitabine, abacavir), NNRTIs (efavirenz), protease inhibitors (usually boosted with ritonavir), and integrase inhibitors (dolutegravir, bictegravir), which are now first-line. Two nursing points dominate: abacavir requires HLA-B*5701 screening before the first dose because a positive result predicts a potentially fatal hypersensitivity reaction, and adherence is not a soft outcome — missed doses let the virus mutate into resistance. Hepatitis C is now curable in most patients with 8–12 weeks of direct-acting antivirals such as sofosbuvir-based or glecaprevir-pibrentasvir regimens; screen for hepatitis B first, since these drugs can reactivate it.

Section 5Antiparasitics and nursing care

Antiprotozoals

Protozoa are eukaryotes too, so once again the safety margin is narrow and the drugs are chosen around the parasite's life stage rather than just its name. Malaria is the clearest example. Artemisinin-based combination therapy (artemether-lumefantrine) is first-line for uncomplicated P. falciparum and should be taken with fatty food, which dramatically improves absorption. Atovaquone-proguanil and doxycycline serve for prophylaxis; chloroquine still works where resistance is absent, and long-term use risks irreversible retinopathy. The critical piece is the dormant liver form, the hypnozoite, of P. vivax and P. ovale: treating the blood stage alone leaves it in place and the patient relapses months later. Clearing it requires primaquine or tafenoquine — and both cause severe hemolysis in G6PD deficiency, so screen G6PD before the dose, without exception.

Beyond malaria, metronidazole or tinidazole covers giardiasis, amebiasis, and trichomoniasis. For trichomoniasis, treat the partner too or the patient simply gets it back — and reinforce the alcohol warning, since these are the drugs behind the disulfiram-like reaction. Nitazoxanide covers Giardia and Cryptosporidium. TMP-SMX remains the drug of choice for Pneumocystis pneumonia (an organism reclassified as a fungus but still taught alongside this group), with pentamidine as an alternative that can cause severe hypoglycemia followed by hyperglycemia.

Anthelmintics

Worms are animals, and the drugs against them are mostly aimed at neuromuscular or cytoskeletal machinery the worm depends on. Albendazole and mebendazole block the worm's microtubule assembly, starving it; albendazole is absorbed far better with a fatty meal. Ivermectin opens glutamate-gated chloride channels, paralyzing the parasite — mammals have no such channels at all, and the blood-brain barrier keeps the drug away from the similar channels in the human CNS — it treats strongyloidiasis, onchocerciasis, and scabies. Praziquantel makes the tegument of flukes and tapeworms leak calcium, causing paralysis; take with food and warn about dizziness. Pyrantel pamoate is the over-the-counter pinworm option.

The teaching matters as much as the drug. Pinworm is a household diagnosis: treat all household members, repeat the dose in two weeks to catch newly hatched eggs, wash bed linens and underwear in hot water, cut and scrub fingernails, and collect the diagnostic tape test first thing in the morning before bathing. That set of instructions prevents more reinfection than any second prescription.

Nursing care that applies to every antimicrobial

Strip away the class differences and the same nursing spine holds up all of it. Before: take a real allergy history, get the culture, check renal and hepatic function against the drug and the dose, review interactions, and confirm pregnancy status where it matters. During: give doses on schedule and evenly spaced around the clock so blood levels stay above the MIC — a "late" antibiotic is not a trivial late medication. Stay with the patient for the first dose of anything new. Draw troughs immediately before the next dose and peaks at the specified interval after it, and chart the exact times, because a level drawn at the wrong moment is worse than no level at all: it will be acted upon. After: watch for the response you expect (fever curve, white count, the wound), for the toxicity you were warned about (creatinine, CBC, LFTs, hearing, tendons, QT), and for the superinfection you invited — new diarrhea, white patches in the mouth, vaginal itching.

ReferenceWords worth knowing

The vocabulary of antimicrobial therapy — skim it now, then come back whenever a term on a culture report or a drug label stops you.

Aminoglycoside

A bactericidal class (gentamicin, tobramycin, amikacin) that binds the 30S ribosomal subunit; nephrotoxic and ototoxic, requiring peak and trough monitoring.

Anthelmintic

A drug that kills or expels parasitic worms, e.g., albendazole, ivermectin, praziquantel.

Antimicrobial stewardship

The coordinated effort to use antimicrobials only when indicated, and then in the right drug, dose, route, and duration.

Bactericidal

Kills bacteria outright; required when host defenses are unavailable (endocarditis, meningitis, neutropenia).

Bacteriostatic

Inhibits bacterial replication and relies on the immune system to clear the organism.

Beta-lactam

Any drug built around the beta-lactam ring — penicillins, cephalosporins, carbapenems, and the monobactam aztreonam — that blocks cell wall cross-linking.

Beta-lactamase

A bacterial enzyme that inactivates beta-lactam drugs by opening the ring; extended-spectrum forms (ESBLs) inactivate a much wider range.

Broad-spectrum

Active against a wide range of organisms; useful empirically but destroys normal flora and drives resistance.

Culture and sensitivity (C&S)

A laboratory test that identifies the organism and reports which drugs inhibit it, with susceptible/intermediate/resistant interpretations.

De-escalation

Narrowing therapy from an empiric broad-spectrum drug to a targeted one once the culture and sensitivity result returns.

Empiric therapy

Treatment started before results are available, based on the likely organisms for that site and patient.

Ergosterol

The sterol in fungal cell membranes (humans use cholesterol); the target of polyenes and the azoles' synthesis pathway.

Methicillin-resistant Staphylococcus aureus (MRSA)

S. aureus carrying mecA, which builds an altered penicillin-binding protein (PBP2a) so that every traditional beta-lactam fails at once; the anti-MRSA cephalosporins ceftaroline (and ceftobiprole) are engineered to bind PBP2a and remain active.

Minimum inhibitory concentration (MIC)

The lowest drug concentration that prevents visible growth of an organism in vitro.

Narrow-spectrum

Active against a limited range of organisms; the goal once the pathogen is identified.

Nephrotoxicity

Drug-induced kidney injury; a signature risk of vancomycin, aminoglycosides, amphotericin B, and colistin.

Ototoxicity

Drug-induced damage to hearing or balance, classically from aminoglycosides; may be permanent, so report tinnitus or vertigo at once.

Peak and trough

Serum drug levels drawn at the expected maximum (peak) and immediately before the next dose (trough) to keep therapy effective and non-toxic.

Prophylaxis

Giving an antimicrobial to prevent infection rather than treat it, e.g., cefazolin within 60 minutes before surgical incision.

Selective toxicity

Harming the microbe while sparing the patient by attacking a structure the microbe has and human cells lack.

Superinfection

A new infection that appears during antimicrobial therapy because the protective normal flora were destroyed, e.g., C. difficile colitis or thrush.

Vancomycin-resistant Enterococcus (VRE)

Enterococcus that has altered the D-alanine binding site vancomycin depends on; usually treated with linezolid or daptomycin.

Immunomodulators & Antineoplastic Agents

Most drugs help a patient by turning a body system up or down a little. The drugs in this chapter do something far more consequential: they rewrite the terms on which the immune system operates, or they poison cell division itself. That power is exactly why they work — a transplanted kidney survives, a lupus flare quiets, a lymphoma melts away — and exactly why they hurt. An immunosuppressed patient cannot mount a fever the way you expect. A chemotherapy patient loses the lining of the gut and the blood-forming marrow along with the tumor. This chapter walks you through the drugs that quiet immunity, the drugs that wake it up, and the drugs that kill dividing cells — and, at every step, what the nurse watches, teaches, and refuses to let slide.

Section 1Immunosuppressants

Why we deliberately weaken a defense system

The immune system is superb at one job: telling self from not-self and destroying the not-self. That instinct becomes a problem in exactly two situations. In transplantation, the donated organ is not-self, and an untreated immune system will reject it within days. In autoimmune disease — rheumatoid arthritis, lupus, Crohn disease, multiple sclerosis, psoriasis — the system has misfiled the patient's own tissue as foreign and is attacking it. In both cases we give drugs to turn the response down. There is no free lunch here: every bit of immunity we take away is immunity that was also guarding against bacteria, viruses, fungi, and cancer cells.

Transplant regimens are usually built in two stages. Induction therapy is heavy and brief, given around the time of surgery — basiliximab (an interleukin-2 receptor antagonist) or antithymocyte globulin. Maintenance therapy is lifelong and usually combines three drugs from different classes at lower doses each: a calcineurin inhibitor, an antiproliferative, and a corticosteroid. Using three mechanisms at modest doses beats using one at a huge dose, because the toxicities do not stack in the same organ.

The classes worth knowing cold

Calcineurin inhibitors — cyclosporine and tacrolimus — are the backbone of transplant care. They block the calcineurin signal that a T cell needs to make interleukin-2, so the T cell never proliferates. Both have a narrow therapeutic index: too little and the graft rejects, too much and the kidneys fail. Trough levels are drawn immediately before the next dose, and the whole regimen lives or dies on the patient taking it at the same times every day. Both are metabolized by CYP3A4, which is why grapefruit juice, azole antifungals, and clarithromycin raise levels dangerously, while rifampin, phenytoin, and St. John's wort drop them toward rejection.

Antiproliferatives starve lymphocytes of the DNA building blocks they need to divide. Mycophenolate is the modern standard; azathioprine is older and carries one of the most famous interactions in pharmacology — giving allopurinol alongside it blocks xanthine oxidase, the enzyme that clears azathioprine's active metabolite, so drug levels climb and can cause catastrophic marrow failure. mTOR inhibitors (sirolimus, everolimus) spare the kidney but impair wound healing, so they are typically held in the immediate post-op period. Corticosteroids blunt nearly every arm of inflammation and are effective, cheap, and toxic in a dozen directions; they are tapered, never stopped abruptly, because chronic use suppresses the adrenal axis.

On the autoimmune side, low-dose methotrexate is the anchor drug for rheumatoid arthritis, and here is the fact that saves lives: it is dosed once weekly, not daily. Daily dosing of a weekly methotrexate order has killed patients. Folic acid is given on the other days to reduce mucositis and marrow toxicity. Biologic DMARDs — the TNF inhibitors etanercept, adalimumab, and infliximab — are extraordinarily effective and require latent tuberculosis screening before the first dose, because knocking out TNF lets walled-off TB break loose.

Infection is the whole risk

An immunosuppressed patient does not present the way your textbook patient presents. Steroids blunt fever. Neutropenia removes the cells that make pus, so a wound infection may show no drainage and pneumonia may show a nearly clear chest film. The classic signs of inflammation are, in part, the immune system working — and you have turned it off. This means the threshold for concern drops through the floor: a low-grade temperature, a new cough, a sore throat, a small area of redness, or simply "I don't feel right" all get taken seriously and reported.

Prophylaxis is standard rather than optional in this population — typically trimethoprim–sulfamethoxazole against Pneumocystis jirovecii, an antiviral against cytomegalovirus, and an antifungal in high-risk patients. Live vaccines are contraindicated in significant immunosuppression, and they should be brought up to date before transplant or before starting a biologic. Long-term, these patients also carry a real excess risk of malignancy — skin cancer above all — so sunscreen, protective clothing, and annual skin checks are legitimate nursing teaching, not filler.

Section 2Immunostimulants and vaccines

Drugs that wake the immune system up

If immunosuppressants turn the dial down, immunostimulants turn it up — either by rebuilding cells the immune system has lost, or by releasing a brake that a tumor has been exploiting. The most common ones you will hang are the colony-stimulating factors. Filgrastim and its long-acting cousin pegfilgrastim are manufactured versions of G-CSF; they tell the marrow to pump out neutrophils and are given after chemotherapy to shorten the window of dangerous neutropenia. The classic side effect is deep, aching bone pain — the marrow is literally working overtime — and it is usually managed with acetaminophen or an NSAID rather than by stopping the drug. Timing matters: these are given at least twenty-four hours after chemotherapy, never alongside it, because you do not want to hand freshly stimulated dividing marrow cells to a drug that kills dividing cells.

Erythropoiesis-stimulating agents (epoetin alfa, darbepoetin) raise hemoglobin but carry a boxed warning: pushed too high, they shorten survival in some cancers and cause thrombosis and stroke. They are used at the lowest dose that avoids transfusion, not to make the number look pretty. Interferons (interferon alfa-2b; interferon beta for multiple sclerosis) reliably produce flu-like symptoms — fever, chills, myalgia — and can cause depression severe enough to require screening. Interleukin-2 (aldesleukin) is powerful and dangerous, with capillary leak syndrome as its defining toxicity.

The most important recent class is the immune checkpoint inhibitors — pembrolizumab and nivolumab (anti–PD-1), atezolizumab (anti–PD-L1), and ipilimumab (anti–CTLA-4). Tumors survive partly by pressing the immune system's own "stand down" buttons; these drugs cut that wire. The result is a reawakened immune system that sometimes attacks the patient too, producing immune-related adverse events: colitis, pneumonitis, hepatitis, thyroiditis, dermatitis, hypophysitis. Any new diarrhea, cough, or shortness of breath in a patient on a checkpoint inhibitor is reported — these are treated with corticosteroids, and delay does real harm.

A quick decoder for biologic names, because it genuinely helps: -mab means monoclonal antibody, -cept means a receptor fusion protein, -nib means a small-molecule kinase inhibitor, and -kin or -grastim flags a cytokine or growth factor.

Vaccines: borrowing the memory without the disease

A vaccine is the most cost-effective drug there is. It shows the adaptive immune system a harmless preview of a pathogen so that memory B and T cells are already standing by when the real thing arrives — active immunity, slow to build but long-lasting. Contrast that with passive immunity, where we simply inject someone else's ready-made antibodies: immune globulin, Rh_o(D) immune globulin, rabies or tetanus immune globulin. Passive protection works within minutes and fades within weeks, because the patient made no memory of their own. Use active for prevention, passive for a threat that is already here.

Vaccine administration is a nursing skill with a few non-negotiables. Give the Vaccine Information Statement before the injection and document that you did. Have epinephrine immediately available and observe for at least fifteen minutes afterward, longer if there is any history of reaction. Document lot number, expiration, site, and route — this is one of the few places where charting is itself a public health function. Teach that soreness, a low-grade temperature, and fatigue for a day mean the vaccine is working, and treat them with acetaminophen; do not give aspirin to a child. And know the real contraindications from the false ones: a serious allergy to a vaccine component or a previous anaphylactic reaction is a genuine contraindication; a mild cold, a runny nose, breastfeeding, or a family history of reactions is not.

Section 3Antineoplastic principles

The cell cycle, and why it is the target

Cancer is, at bottom, a disease of division that will not stop. So the oldest and still most widely used strategy against it is to attack division itself. To understand where each drug lands, you need the cycle. G₁ is growth: the cell enlarges and manufactures the enzymes it will need. S is synthesis: DNA is copied, and the cell is at its most chemically vulnerable here. G₂ is the second growth phase, building the spindle apparatus and proofreading the new DNA. M is mitosis, when the chromosomes are pulled apart and the cell splits in two. And G₀ is the resting state — the cell is alive and working but not dividing. G₀ is the hiding place. Cell-cycle–specific drugs cannot touch a cell in G₀ at all, and even the nonspecific ones work on it poorly — a resting cell is not copying DNA and has time to repair the damage it does take. That sanctuary is a large part of why cancers relapse years later.

That geography splits antineoplastics into two groups. Cell-cycle–specific (CCS) drugs only work on a cell that is in a particular phase: antimetabolites act in S, mitotic inhibitors act in M, bleomycin acts in G₂. Because they need to catch the cell in the act, they work best against fast-growing tumors and are often given as a continuous infusion or in divided doses to widen the window. Cell-cycle–nonspecific (CCNS) drugs — alkylating agents, most antitumor antibiotics (the anthracyclines, dactinomycin, mitomycin), and platinum compounds — damage DNA whenever they find it, including in G₀. Bleomycin is the antitumor-antibiotic exception: it is cell-cycle–specific and acts predominantly in G₂. The nonspecific agents are typically given as a single large bolus, because the damage is dose-dependent rather than timing-dependent.

Log kill, growth fraction, and why chemo comes in cycles

Here is the idea that explains the entire structure of a chemotherapy regimen: a given dose of a drug kills a constant percentage of tumor cells, not a constant number. This is the log kill hypothesis, sometimes called fractional kill. If a dose kills 99.9 percent of a billion cancer cells, a million are still alive. The next cycle kills 99.9 percent of the million, leaving a thousand. You can see immediately why one round is never enough, why the schedule is a schedule and not a suggestion, and why a patient who feels wonderful after two cycles still needs the other four.

The gaps between cycles are equally deliberate. Normal marrow recovers from chemotherapy faster than tumor does, so a rest period of two to three weeks lets the patient's blood counts climb back while the tumor gets comparatively less benefit. Combination chemotherapy follows the same logic from a different angle: drugs are chosen with different mechanisms, different resistance patterns, and — crucially — non-overlapping toxicities, so that no single organ takes the whole hit. Dosing is calculated by body surface area in mg/m² rather than by weight, and carboplatin is dosed by target AUC using the patient's renal function. Small errors in these calculations are not small; this is why chemotherapy orders require an independent double-check by a second qualified clinician.

Why chemotherapy hurts the patient too

Traditional chemotherapy cannot tell a cancer cell from a healthy cell. It can only tell a dividing cell from a resting one. That is the entire tragedy of the drug class in one sentence — and it lets you predict every major side effect before you ever open the drug book. Ask yourself which normal tissues in the body divide fast, and you have your answer.

Two more principles round out the picture. Growth fraction — the proportion of a tumor's cells actively cycling — predicts responsiveness: leukemias and lymphomas with high growth fractions melt away, while slow, bulky solid tumors respond far less. And drug resistance develops, most notoriously through multidrug resistance proteins such as P-glycoprotein, which sit in the cell membrane and pump the drug straight back out. Resistance is another reason we combine drugs and another reason we do not stretch out the schedule.

Section 4Chemotherapy classes

Damaging the DNA: alkylating agents and antitumor antibiotics

Alkylating agents are the oldest class — descendants of the sulfur mustard gas of the First World War, whose habit of destroying the bone marrow of exposed soldiers was the clue that led to the nitrogen mustards being tried against lymphoma in the 1940s. They attach an alkyl group to DNA, cross-linking the strands so the double helix can no longer unzip and copy itself. They are cell-cycle–nonspecific and broadly effective, and each subgroup carries a signature toxicity. Cyclophosphamide breaks down into acrolein, which sits in the bladder and burns it — hemorrhagic cystitis, prevented with aggressive hydration, frequent voiding, and the rescue agent mesna. Ifosfamide does the same and adds neurotoxicity. The nitrosoureas such as carmustine cross the blood–brain barrier (useful for brain tumors) and cause a notoriously delayed myelosuppression that nadirs four to six weeks out. The platinum compounds are grouped here by behavior: cisplatin is nephrotoxic, ototoxic, and one of the most emetogenic drugs in medicine; carboplatin trades that for marrow suppression; oxaliplatin produces a strange cold-triggered neuropathy — patients must be taught not to drink cold liquids or touch cold metal for days after a dose.

Antitumor antibiotics come from soil bacteria and intercalate into DNA, generating free radicals that shred it. The anthracyclines — doxorubicin, daunorubicin, epirubicin — are among the most useful drugs in oncology and among the most feared, because their cardiotoxicity is cumulative and largely irreversible. A lifetime dose ceiling (roughly 550 mg/m² for doxorubicin) is tracked across the patient's entire history, a baseline ejection fraction is measured by echocardiogram or MUGA, and dexrazoxane may be given as a cardioprotectant. Doxorubicin is also a potent vesicant and turns urine red-orange for a day or two — harmless, but terrifying if nobody warned the patient. Bleomycin is the exception twice over: alone in this class it is cell-cycle–specific, acting in G₂, and it causes almost no myelosuppression, causing instead pulmonary fibrosis, with its own cumulative lifetime limit and a baseline pulmonary function test.

Starving and stalling: antimetabolites and mitotic inhibitors

Antimetabolites are molecular impostors. They look enough like the natural building blocks of DNA that the cell picks them up and jams its own machinery — so they act in the S phase and are strongly cell-cycle–specific. Methotrexate blocks dihydrofolate reductase and starves the cell of folate; high-dose regimens are followed by leucovorin rescue, which restores folate to normal cells. Never give NSAIDs or salicylates with high-dose methotrexate — they delay its clearance and can cause fatal toxicity. 5-fluorouracil and its oral prodrug capecitabine cause mucositis, diarrhea, and the palms-and-soles redness of hand–foot syndrome. Cytarabine adds a distinctive cerebellar toxicity and a chemical conjunctivitis prevented with corticosteroid eye drops.

Mitotic inhibitors attack the spindle in the M phase, and they do it from opposite directions. The vinca alkaloids (vincristine, vinblastine) prevent microtubules from assembling; the taxanes (paclitaxel, docetaxel) do the reverse, freezing microtubules so they cannot disassemble. Either way, mitosis stops. Vincristine's dose-limiting problem is peripheral neuropathy — numb fingertips, foot drop, and an autonomic constipation that can progress to ileus, which is why a bowel regimen goes out with the drug. And vincristine carries the most absolute rule in oncology nursing: it is labeled "For intravenous use only — fatal if given by other routes," because intrathecal administration causes ascending paralysis and death. Taxanes cause hypersensitivity reactions from their solvent, so patients are premedicated with a corticosteroid, an antihistamine, and an H₂ blocker, and paclitaxel is infused through non-PVC tubing with an in-line filter.

Aiming instead of carpet-bombing: targeted and hormonal therapy

Everything above kills dividing cells indiscriminately. Targeted therapy asks a better question: what is broken in this tumor specifically? Imatinib shuts down the BCR-ABL kinase that drives chronic myeloid leukemia and turned a fatal disease into a manageable one. Trastuzumab targets HER2-positive breast cancer and causes cardiotoxicity that is, unlike doxorubicin's, usually reversible — but the two together are a bad combination. Rituximab targets CD20 on B cells and can reactivate hepatitis B, so screening comes first. Bevacizumab starves tumors of blood supply by blocking VEGF, at the cost of hypertension, bleeding, impaired wound healing, and rare GI perforation. Targeted drugs are gentler on the marrow but not gentle — they simply trade one toxicity profile for another. Hormonal agents work the same logic on hormone-driven tumors: tamoxifen blocks estrogen at the breast (and raises the risk of endometrial cancer and clots), the aromatase inhibitors anastrozole and letrozole cut estrogen production in postmenopausal women (at the cost of joint pain and bone loss), and leuprolide suppresses testosterone in prostate cancer after an initial tumor flare.

Section 5Chemotherapy toxicities and nursing care

Myelosuppression: the toxicity that limits the dose

For most regimens, the marrow decides how much drug a patient can have. Counts fall after each cycle, hit bottom — the nadir — usually seven to fourteen days later, and recover over the following two to three weeks. The three cell lines fail on their own schedule, and each produces its own emergency.

Neutropenia is the deadliest. The absolute neutrophil count, not the white count, is what matters: an ANC below 1,000/mm³ is serious and below 500/mm³ is severe. Febrile neutropenia is an oncologic emergency — a single oral temperature of 38.3°C (101°F), or 38.0°C (100.4°F) sustained for an hour, in a neutropenic patient means blood cultures now and broad-spectrum antibiotics within one hour. Not after rounds. Not after the culture results. Within the hour, because there are no neutrophils to hold the line and a patient can go from a low fever to septic shock in a few hours. Teach the patient that fever at home means calling immediately and going to the emergency department, not waiting until morning.

Neutropenic precautions are largely about removing sources of organisms and removing breaks in the skin: meticulous hand hygiene by everyone, no fresh flowers or standing water, no unpasteurized or raw foods, no crowds or sick visitors, and — a favorite of exam writers because it is genuinely important — no rectal temperatures, suppositories, or enemas, since a tear in the rectal mucosa in a neutropenic patient is a direct line to the bloodstream. Thrombocytopenia brings bleeding precautions below roughly 50,000/mm³ and spontaneous bleeding risk below 20,000/mm³: electric razor, soft toothbrush, no aspirin or NSAIDs, no IM injections, no flossing, and fall prevention. Anemia is the least dramatic and the most complained about — profound fatigue, dyspnea on exertion, and a life shrunk down to the couch. Take it seriously; it is what patients remember.

Nausea, mouth, hair, and the things patients actually fear

Chemotherapy-induced nausea and vomiting comes in three flavors and they are managed differently. Acute emesis begins within a few hours. Delayed emesis starts more than twenty-four hours out and is the specialty of cisplatin and cyclophosphamide — patients get home, feel fine, and then are ambushed. Anticipatory nausea is conditioned: the patient vomits in the parking lot before the drug ever hangs, and the answer is a benzodiazepine such as lorazepam plus better control of the first cycle. The single most important principle is that antiemetics are given prophylactically and on a schedule, before the chemotherapy — never PRN, never chasing. Modern regimens combine a 5-HT₃ antagonist (ondansetron — watch the QT interval), an NK-1 antagonist (aprepitant), dexamethasone, and often olanzapine.

Mucositis makes eating a misery and is a portal for infection. Assess the mouth every day, and teach a soft toothbrush, saline or sodium bicarbonate rinses several times daily, and no alcohol-based mouthwash — it is like pouring astringent on a burn. Oral cryotherapy (ice chips during a short 5-FU infusion) genuinely helps. Alopecia is not medically dangerous and is often the thing patients grieve most; it typically starts one to three weeks in, involves brows, lashes, and body hair as well as scalp, and it grows back — sometimes a different color or texture. Encourage choosing a wig or head covering before the hair falls, because matching it afterward is harder; scalp cooling reduces loss with some regimens. Teach scalp sun protection and gentle care.

Extravasation and the drugs you never take your eyes off

A vesicant is a drug that causes tissue necrosis if it leaks out of the vein. The anthracyclines, the vinca alkaloids, mechlorethamine, and mitomycin are the classic offenders, and the damage from a leak can go to tendon and bone and end in grafting or amputation. Prevention is the entire strategy: a central line for vesicants whenever possible, a fresh site with confirmed blood return, no site over a joint or in an antecubital fossa, and a nurse who stays and watches rather than starting it and stepping out.

If the patient reports burning or stinging, or you see swelling, redness, resistance to injection, or loss of blood return — stop the infusion immediately. Do not pull the needle out. Disconnect the tubing, attempt to aspirate residual drug through the catheter, notify the provider, mark and photograph the area, and elevate the limb. Then the antidote depends on which drug leaked, and the temperature is part of the antidote: for anthracyclines, apply cold and give dexrazoxane or topical DMSO; for vinca alkaloids, apply warm and give hyaluronidase. Cold for anthracyclines localizes the drug; warm for vincas disperses it. Reversing them makes the injury worse.

Protecting yourself and the family

Chemotherapy agents are hazardous drugs: they are carcinogenic, mutagenic, or teratogenic to the people who handle them as well as to the patient. Preparation happens in a biological safety cabinet by trained pharmacy staff, never on a unit counter. Administration requires chemotherapy-rated double gloves and a lint-free, back-closing impermeable gown, eye protection when splashing is possible, and closed-system transfer devices. A spill kit stays where the drug is given, and all chemotherapy waste goes in the designated hazardous stream, not the regular sharps box. Nurses who are pregnant, trying to conceive, or breastfeeding should not handle these agents.

The precautions follow the patient home, because the drug leaves in body fluids. For roughly 48 hours after a dose, teach the family to wear gloves when handling urine, stool, vomit, or soiled linens; to close the toilet lid and flush twice; to wash contaminated laundry separately from the household's; and to wash hands thoroughly afterward. Say this out loud rather than handing over a pamphlet, and say why — families who understand the reason follow it, and families who think they are being told their loved one is "toxic" often feel shame instead. Finally, chemotherapy is a high-alert medication class: two qualified clinicians independently verify the order, the drug, the dose against the body surface area calculation, the route, and the patient's cumulative lifetime totals before anything is hung.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Absolute neutrophil count (ANC)

The number of infection-fighting neutrophils per mm³; below 1,000 is serious, below 500 is severe neutropenia. The number that drives every precaution.

Alkylating agent

A cell-cycle–nonspecific drug that cross-links DNA so it cannot replicate; prototype cyclophosphamide.

Antimetabolite

A drug that mimics a normal DNA building block and jams synthesis in the S phase; prototypes methotrexate and 5-fluorouracil.

Calcineurin inhibitor

An immunosuppressant that blocks interleukin-2 production so T cells cannot proliferate; tacrolimus, cyclosporine.

Cell-cycle–nonspecific (CCNS)

Acts on cells in any phase, including resting G₀; alkylating agents, most antitumor antibiotics (bleomycin is the cell-cycle–specific exception), platinums.

Cell-cycle–specific (CCS)

Acts only on cells in a particular phase; antimetabolites (S), mitotic inhibitors (M), bleomycin (G₂).

Checkpoint inhibitor

A monoclonal antibody that releases the immune system's brakes on a tumor (pembrolizumab, nivolumab, ipilimumab); causes immune-related adverse events.

Extravasation

Leakage of a drug out of the vein into surrounding tissue; with a vesicant, this causes necrosis.

Febrile neutropenia

Fever in a neutropenic patient — an oncologic emergency requiring cultures and broad-spectrum antibiotics within one hour.

G₀ phase

The resting state, where a cell is alive but not dividing; cell-cycle–specific drugs cannot reach it and nonspecific drugs reach it poorly, which is why cancers relapse.

Hazardous drug

An agent carcinogenic, mutagenic, or teratogenic to handlers as well as patients; requires double gloves, gown, closed systems, and dedicated waste.

Immune-related adverse event (irAE)

Autoimmune injury — colitis, pneumonitis, hepatitis, thyroiditis — caused by a checkpoint inhibitor; treated with corticosteroids.

Leucovorin rescue

Giving reduced folate after high-dose methotrexate to restore normal cells while the tumor stays starved.

Live attenuated vaccine

A weakened but replicating organism (MMR, varicella, rotavirus, LAIV, yellow fever); contraindicated in pregnancy and significant immunosuppression.

Log kill hypothesis

Each chemotherapy dose kills a constant percentage of tumor cells, not a constant number — the reason treatment comes in repeated cycles.

Mesna

A rescue agent that binds acrolein in the bladder, preventing the hemorrhagic cystitis caused by cyclophosphamide and ifosfamide.

Mucositis

Inflammation and ulceration of the GI lining, mouth to anus, from loss of rapidly dividing mucosal cells.

Myelosuppression

Chemotherapy-induced shutdown of bone marrow production → neutropenia, thrombocytopenia, anemia; the dose-limiting toxicity of most regimens.

Nadir

The lowest point blood counts reach after a chemotherapy cycle, typically 7–14 days out.

Passive immunity

Protection from borrowed, ready-made antibodies (immune globulin); immediate but temporary, with no memory formed.

Tumor lysis syndrome

Massive cell breakdown releasing potassium, phosphate, and uric acid, dropping calcium and injuring the kidney; prevented with hydration and allopurinol or rasburicase.

Vesicant

A drug that causes tissue necrosis if it extravasates — anthracyclines, vinca alkaloids, mechlorethamine, mitomycin.

Pain & Substance Use

Pain is the reason most people come to us, and relieving it is one of the few things a nurse does that the patient feels within minutes. It is also one of the most dangerous things we do: the drugs that treat pain best are the drugs that stop breathing, poison livers, bleed stomachs, and, for some patients, begin a story that ends in a substance use disorder. This chapter walks the whole arc — how pain is generated and how we measure something we cannot see, the non-opioids with their hard ceilings and quiet toxicities, the opioids with no ceiling at all, the adjuvants that treat pain the classic analgesics cannot touch, and finally the substances people use and the withdrawal syndromes that land them in your care. Along the way, one theme repeats: the drug is only half of it. The other half is the nurse who assesses, monitors, teaches, and refuses to look away.

Section 1Pain and how we assess it

Nociception: four steps, four places to intervene

Pain begins as a physical event and ends as a personal one. The physical part, nociception, happens in four steps, and it is worth learning them as four steps because each analgesic class you will meet in this chapter interrupts a different one.

Transduction is the moment tissue injury becomes an electrical signal. Damaged cells spill potassium, hydrogen ions, bradykinin, histamine, and — importantly — prostaglandins, which do not cause pain so much as lower the threshold of the free nerve endings called nociceptors, so that even a light touch on sunburned skin screams. This is precisely where NSAIDs act: block prostaglandin production and you raise the threshold back toward normal.

Transmission carries that signal to the spinal cord along two very different fibers. Thin, myelinated A-delta fibers conduct fast and deliver the sharp, bright, well-localized "ouch" you feel the instant you touch a hot pan. Unmyelinated C fibers conduct slowly and deliver the dull, burning, aching, poorly localized misery that arrives a second later and stays. In the dorsal horn of the spinal cord, these fibers release glutamate and substance P onto second-order neurons, which cross the midline and ascend the spinothalamic tract to the thalamus. Opioids act mostly here and above, damping the release of substance P and hyperpolarizing the receiving neuron.

Perception is the thalamus relaying to the somatosensory cortex (where is it, how bad), the limbic system (how much do I hate it), and the frontal lobe (what does this mean for me). This is why the same stimulus hurts more when a patient is frightened, exhausted, or alone — and why a warm blanket, an explanation, and a hand on the shoulder are not "soft" interventions but real ones.

Modulation is the body pushing back. From the periaqueductal gray in the midbrain, descending fibers release serotonin and norepinephrine onto the dorsal horn and turn the volume down, and interneurons there release the body's own opioids — endorphins, enkephalins, and dynorphins — onto the very receptors that morphine occupies. Understanding modulation explains an otherwise strange fact: antidepressants that boost serotonin and norepinephrine relieve pain, not because the patient is depressed, but because they strengthen the body's own descending brake. It also explains gate control theory — rubbing a bumped elbow fires large touch fibers that partially close the dorsal-horn "gate" on the pain signal, which is the physiology behind massage, heat, cold, and TENS units.

Acute, chronic, nociceptive, neuropathic

Acute pain has an obvious cause, a predictable course, and an end: it protects, it warns, it resolves as tissue heals. It usually comes with a sympathetic surge — tachycardia, hypertension, diaphoresis, guarding. Chronic pain persists beyond the expected healing time, conventionally about three months. It has often outlived its usefulness, and here is the trap that costs patients dearly: the sympathetic signs are gone. The nervous system adapts. A patient with chronic pain can be sitting quietly with a heart rate of 68, smiling at her grandson on a video call, and be in genuine 8-out-of-10 pain. Nurses who use vital signs and facial expression as a lie detector will under-treat exactly the patients who suffer most.

Cutting a different direction: nociceptive pain comes from actual tissue damage detected by intact nerves and responds well to the classic analgesics. It splits into somatic (skin, muscle, bone — sharp, aching, easy to point to) and visceral (organs — cramping, squeezing, deep, poorly localized, often referred to a distant skin area, like the left arm in myocardial infarction). Neuropathic pain is different in kind: the nerve itself is damaged or misfiring, so the alarm rings with no fire. Patients describe it as burning, shooting, electric, pins-and-needles, or numb-but-painful, and — this is the clinically vital part — it responds poorly to opioids and NSAIDs and well to adjuvants (Section 4). Diabetic neuropathy, postherpetic neuralgia, phantom limb, sciatica, and chemotherapy-induced neuropathy all live here.

Measuring something you cannot see

Pain is subjective. The patient's self-report is the gold standard — pain is whatever the experiencing person says it is, existing whenever they say it does. Your job is not to verify it but to characterize it, and a structured assessment does that: onset, provocation and palliation, quality, region and radiation, severity, timing, and effect on function (the mnemonics OLDCARTS and PQRST both get you there). The last item — function — is the one students skip and the one that matters most in chronic pain, where "Can you sleep? Can you get to the bathroom? Can you play with your grandkids?" is a better outcome measure than any number.

Then pick a scale that matches the patient in front of you. A number means nothing if the patient cannot give you one, and defaulting to the 0–10 scale for a toddler, a patient with advanced dementia, or an intubated ICU patient is how pain gets missed.

Assessment does not end when the pill is swallowed. Reassess: roughly 15–30 minutes after an IV dose, about 60 minutes after an oral dose, and at peak effect for anything else. Chart the reassessment. An unreassessed analgesic is an unfinished intervention, and in a court record it looks exactly like one.

Finally, the modern framework: multimodal analgesia. Rather than climbing the opioid dose, stack drugs with different mechanisms — scheduled acetaminophen plus an NSAID plus a nerve block plus gabapentin plus ice and repositioning — so each does part of the work at a lower, safer dose. The old WHO analgesic ladder (non-opioid → add weak opioid → strong opioid, with adjuvants at every rung) still teaches the principle: start low, add rather than replace, and never skip the non-drug rung.

Section 2Non-opioid analgesics

The ceiling effect, and why it matters

Non-opioid analgesics share a property opioids do not have: a ceiling effect. Past a certain dose, the analgesia stops improving — the enzyme they inhibit is already fully inhibited — but the toxicity keeps climbing in a straight line. Six ibuprofen do not relieve more pain than three; they only bleed more stomachs. Six grams of acetaminophen do not relieve more pain than three; they only kill more hepatocytes. This is the single most important patient-teaching point in the whole class, because the intuitive human response to inadequate relief is to take more. The correct response is to add a different mechanism, not more of the same one.

Their other shared virtues: they do not cause respiratory depression, they do not cause dependence, they do not sedate, and they are the foundation the rest of the analgesic plan is built on. Scheduled acetaminophen around the clock after surgery measurably lowers the opioid a patient needs — that is called opioid sparing, and it is the whole point.

Acetaminophen: the gentle one that destroys livers

Acetaminophen (paracetamol; Tylenol) relieves pain and lowers fever, apparently by inhibiting cyclooxygenase centrally in the CNS. What it does not do is as important as what it does: it has essentially no anti-inflammatory effect, no antiplatelet effect, and it does not ulcerate the stomach or injure the kidney the way NSAIDs do. That makes it the analgesic of choice for people who cannot take NSAIDs — patients with peptic ulcer disease, chronic kidney disease, bleeding risk, anticoagulation, heart failure, and pregnancy — and the first-line antipyretic for children. For osteoarthritis it is a reasonable first trial and the safest option when NSAIDs are contraindicated, but be honest about the evidence: current guidelines favor topical or oral NSAIDs, because acetaminophen's benefit in osteoarthritis is modest at best.

The danger is dose. Most acetaminophen is glucuronidated and sulfated into harmless metabolites, but a small fraction goes through CYP2E1 to a vicious intermediate called NAPQI, which glutathione immediately neutralizes. Overwhelm the dose — or start with a glutathione reserve already depleted by chronic alcohol use, malnutrition, or fasting — and NAPQI runs out of chaperones and binds hepatocytes directly, producing centrilobular hepatic necrosis. Acetaminophen is the leading cause of acute liver failure in the United States, and a great deal of it is accidental.

Accidental, because acetaminophen hides. It is inside oxycodone/acetaminophen and hydrocodone/acetaminophen tablets, inside nighttime cold-and-flu powders, inside sinus tablets and menstrual formulas. A patient who takes two Percocet every six hours and a NyQuil at bedtime and two Tylenol for a headache has not been careless — they have been sold a maze. Your job is to add up every source. The healthy-adult maximum is 4 g in 24 hours, but many clinicians teach a more conservative 3 g/day, and in chronic liver disease, chronic heavy alcohol use, or frailty, 2 g/day or less.

Overdose is deceptive in the first day: nausea, vomiting, diaphoresis, malaise, or nothing at all, while the liver is already being injured. At 24–72 hours the right upper quadrant hurts and AST/ALT climb; at 72–96 hours hepatotoxicity peaks with jaundice, coagulopathy, encephalopathy, and possibly death. The antidote is acetylcysteine, which restores glutathione stores — and it is dramatically most effective when started within 8–10 hours of ingestion. Do not wait for symptoms and do not wait for the level to be "impressive." Get a 4-hour post-ingestion level, plot it on the Rumack-Matthew nomogram, and start acetylcysteine if there is any doubt. Oral acetylcysteine smells and tastes like rotten eggs; the IV form can cause an anaphylactoid reaction (flushing, wheeze, hypotension) that is usually managed by slowing the infusion rather than stopping the drug.

NSAIDs: three drugs in one, and a toxicity for each organ

NSAIDs inhibit cyclooxygenase and so shut down prostaglandin synthesis. Because prostaglandins sensitize nociceptors, drive inflammation, and reset the hypothalamic thermostat, one drug buys you three effects: analgesic, anti-inflammatory, and antipyretic. That anti-inflammatory action is exactly what acetaminophen lacks and exactly why NSAIDs beat it for sprains, gout, dysmenorrhea, renal colic, and inflammatory arthritis.

The problem is that COX comes in two flavors and the useful one is not the only one you hit. COX-1 is the housekeeper: its prostaglandins protect gastric mucosa, maintain renal blood flow, and enable platelet aggregation (via thromboxane A2). COX-2 is mostly induced at sites of inflammation. A nonselective NSAID blocks both — you get the relief from COX-2 inhibition and the toxicity from COX-1 inhibition. That single sentence explains every adverse effect on the list:

• GI: dyspepsia, erosions, peptic ulcer, and painless GI bleeding (the drug is an analgesic — it masks the warning). Take with food or milk; add a PPI in high-risk patients; teach patients to report black tarry stools or coffee-ground emesis.
• Renal: prostaglandins dilate the afferent arteriole. Remove them from a patient who is dehydrated, elderly, or in heart failure and glomerular filtration falls — acute kidney injury. Watch for the "triple whammy": an ACE inhibitor or ARB + a diuretic + an NSAID together is a well-known recipe for AKI. Monitor creatinine, urine output, and weight.
• Cardiovascular: a boxed warning for increased risk of myocardial infarction and stroke, worse at higher doses and longer duration, and contraindicated for perioperative pain in CABG surgery. NSAIDs also cause sodium and water retention — they raise blood pressure and destabilize heart failure.
• Bleeding: impaired platelet function; hold before surgery per protocol; additive with anticoagulants.
• Respiratory: can trigger bronchospasm in aspirin-exacerbated respiratory disease (the asthma / nasal polyps / aspirin-sensitivity triad).
• Pregnancy: the same prostaglandin blockade that protects the stomach and the kidney is also holding a fetal blood vessel open. Avoid NSAIDs from 20 weeks’ gestation onward — fetal prostaglandin inhibition impairs fetal renal function and causes oligohydramnios (an FDA warning since 2020) — and treat them as contraindicated in the third trimester, when they can cause premature closure of the ductus arteriosus. Near delivery they also prolong labor and increase maternal and neonatal bleeding. Acetaminophen is the analgesic of choice in pregnancy; the one deliberate exception is low-dose aspirin (81 mg) prescribed for preeclampsia prevention.

Celecoxib is COX-2 selective, so it spares the stomach considerably — but it still carries renal and cardiovascular risk, and because it is a sulfonamide, ask about sulfa allergy. Ketorolac is the outlier worth memorizing: an injectable NSAID with genuinely opioid-like potency for acute pain, which is wonderful, and a correspondingly brutal GI and renal risk profile, which is why total therapy — all routes combined — is limited to 5 days.

Aspirin belongs here but behaves differently. It inhibits COX irreversibly, so a single dose disables a platelet for its entire 7–10 day life — useless as a feature when you want analgesia, invaluable when you want cardioprotection at low dose. Two aspirin-specific alarms: Reye syndrome, an acute encephalopathy with fatty liver, means aspirin is avoided in children and teens with a viral illness (influenza, varicella), and salicylism — tinnitus, hearing loss, dizziness, hyperventilation — is the early warning of toxicity. Ringing in the ears is a drug level, not a coincidence.

Section 3Opioids

One receptor family, every effect on the list

Opioids work because the body already has an opioid system — endorphins, enkephalins, and dynorphins acting at receptors we borrow. The one that matters most is the mu receptor, and nearly everything you need to know about opioids falls out of a single fact: analgesia and respiratory depression come from the same receptor. You cannot have one without risking the other. Mu activation gives analgesia, euphoria, sedation, respiratory depression, constipation, miosis, and physical dependence. Kappa activation gives analgesia and sedation but tends toward dysphoria rather than euphoria. Delta contributes to analgesia and mood.

Opioids come in four flavors, and knowing which one is in your hand tells you what will happen:

• Full agonists — morphine (the prototype), hydromorphone, fentanyl, oxycodone, hydrocodone, methadone, codeine, tramadol. These have no analgesic ceiling: increase the dose and you get more relief — and more respiratory depression. Nothing but the patient's tolerance and your monitoring stands between the two.
• Partial agonist — buprenorphine. It binds mu tightly but activates it only partly, so it has a ceiling on respiratory depression, which makes it comparatively safe. Because it binds so tightly, it will displace a full agonist and can precipitate withdrawal in someone who is opioid-dependent.
• Agonist-antagonists — butorphanol, nalbuphine (kappa agonist, mu antagonist). Ceiling on respiratory depression, lower abuse potential, more dysphoria — and, again, they can precipitate withdrawal in a patient on a full agonist. Never give nalbuphine casually to a patient on chronic morphine.
• Antagonists — naloxone, naltrexone, and the peripherally acting methylnaltrexone and naloxegol. They occupy the receptor and do nothing.

Respiratory depression: sedation comes first

Opioids blunt the medullary chemoreceptors' response to rising carbon dioxide, so the patient simply stops feeling the urge to breathe. Here is the point that saves lives and that students consistently get backwards on exams and at the bedside: sedation precedes respiratory depression. The respiratory rate is a late sign. By the time you count 6 breaths a minute, you are already late. The early sign is a patient who is unusually drowsy, who drifts off mid-sentence, who needs a shake instead of a word. That is why the POSS (Pasero Opioid-induced Sedation Scale) exists: assess sedation on every opioid check, and when the patient becomes difficult to arouse, hold the next dose and notify — before the rate falls.

Risk stacks: opioid-naive patients, the first 24 hours of therapy, obesity or untreated obstructive sleep apnea, age, renal or hepatic impairment, and above all co-administered CNS depressants — benzodiazepines, alcohol, sedating antihistamines, gabapentinoids, muscle relaxants. The opioid-plus-benzodiazepine combination carries a boxed warning for a reason.

The classic overdose triad is depressed level of consciousness, pinpoint pupils, and respiratory depression. The reversal agent is naloxone: IV onset in 1–2 minutes, also given IM, subcutaneously, or intranasally by a bystander. Two things about naloxone must be automatic. First, titrate to respiratory rate, not to consciousness — dumping a full dose into a patient in pain strips every receptor at once and produces agony, vomiting, hypertension, tachycardia, and in the opioid-dependent, violent precipitated withdrawal. Second, and more dangerous: naloxone's duration (roughly 30–90 minutes) is shorter than most opioids. The patient wakes up, everyone relaxes, the naloxone wears off, and the opioid that is still on board re-sedates them. Every naloxone administration is followed by continued monitoring and, often, repeat doses or an infusion. This is also the entire teaching point of take-home naloxone kits: give the dose, then call emergency services and stay.

The rest of the effect list, and the traps

Constipation deserves its own paragraph because it is the effect to which tolerance never develops. Every other opioid effect fades with time; the bowel does not adapt. A patient on chronic opioids without a bowel regimen is a patient headed for impaction. Start a stimulant laxative (senna) with or without a stool softener on the same order as the opioid, not after the problem appears. For refractory opioid-induced constipation, the peripherally acting antagonists — methylnaltrexone, naloxegol — block gut mu receptors without crossing into the brain, so the bowel moves and the analgesia stays.

Also expect nausea and vomiting (usually tolerance develops in days), pruritus and flushing from histamine release (worst with morphine — it is not an allergy), urinary retention, orthostatic hypotension, miosis, and biliary spasm.

Individual drugs carry individual traps. Morphine has an active metabolite that accumulates in renal impairment — prolonged sedation, so hydromorphone or fentanyl is usually preferred as kidney function falls. Meperidine produces the neurotoxic metabolite normeperidine, which causes tremors and seizures, and it is avoided in older adults and renal impairment; it has largely been abandoned. Codeine and tramadol are prodrugs activated by CYP2D6, which varies enormously between people: ultrarapid metabolizers generate a surge of active drug, which is why both are contraindicated in children under 12 and after tonsillectomy or adenoidectomy in anyone under 18. Tramadol also inhibits serotonin and norepinephrine reuptake — so it lowers the seizure threshold and can contribute to serotonin syndrome. Methadone has a long, unpredictable half-life (it accumulates for days after the pain relief has faded) and prolongs the QT interval. Fentanyl transdermal patches are for opioid-tolerant patients only — never opioid-naive, never acute pain: onset takes 12–24 hours, and heat (fever, heating pad, hot bath, sauna) accelerates absorption into an overdose. Remove the old patch when applying the new one, and teach patients to fold used patches sticky-side together and dispose of them safely — a used patch still contains enough drug to kill a child or a pet.

Tolerance, dependence, and the words we use

Three phenomena get confused constantly, and the confusion harms patients. Tolerance is pharmacologic: the same dose produces less effect over time, so the dose must rise. Physical dependence is also pharmacologic: the body has adapted, and abrupt cessation or an antagonist produces a withdrawal syndrome. Both are expected, normal, predictable responses to sustained opioid exposure and neither one means addiction. Opioid use disorder is a diagnosable condition defined by compulsive use, loss of control, craving, and continued use despite harm. A patient with metastatic cancer on 200 mg of morphine a day is tolerant and physically dependent and, in all likelihood, not addicted at all. There is also pseudoaddiction: a genuinely under-treated patient who watches the clock, requests specific drugs, and looks "drug-seeking" — and whose behavior evaporates the moment the pain is adequately treated.

Opioids are high-alert medications. That means independent double checks per policy, careful attention to mg-versus-mcg, and, with patient-controlled analgesia (PCA), one absolute rule: only the patient presses the button. "PCA by proxy" — a well-meaning family member pushing the button for a sleeping patient — defeats the built-in safety feature (a patient too sedated to press cannot overdose themselves) and has killed people. Teach the patient and the family, keep naloxone and a bag-valve mask accessible, and monitor sedation, respiratory rate, and pulse oximetry (with capnography for high-risk patients).

Section 4Adjuvants and migraine drugs

What an adjuvant is, and why it is not a consolation prize

An adjuvant analgesic (or co-analgesic) is a drug whose day job is something else — treating seizures, depression, inflammation, muscle spasm — but which relieves pain in particular situations. Students sometimes read that as "second string." It is the opposite. For neuropathic pain, adjuvants are first-line and opioids are the disappointing option. When a nerve is the problem, adding morphine mostly adds sedation and constipation; adding gabapentin or duloxetine adds relief.

The gabapentinoids, gabapentin and pregabalin, bind the alpha-2-delta subunit of voltage-gated calcium channels on overexcited neurons and reduce the release of excitatory neurotransmitters — they turn down a nerve that is shouting. They are used for diabetic neuropathy, postherpetic neuralgia, fibromyalgia (pregabalin), and increasingly as part of multimodal postoperative regimens. Expect dizziness, somnolence, ataxia, peripheral edema, weight gain, and blurred vision; both are renally cleared, so dose must be reduced in kidney impairment and older adults are far more sensitive. Two safety points: do not stop them abruptly (taper — abrupt withdrawal can trigger seizures in patients using them for epilepsy), and respect the labeled warning about serious respiratory depression when combined with opioids or other CNS depressants, especially in the elderly or in COPD. Pregabalin is a controlled substance (schedule V).

The antidepressants work by strengthening the descending inhibitory pathway from Section 1 — more serotonin and norepinephrine in the dorsal horn means a stronger brake. Tricyclics (amitriptyline, nortriptyline) are effective at doses well below antidepressant doses, and their anticholinergic burden is the limiting factor: dry mouth, constipation, urinary retention, blurred vision, orthostatic hypotension, sedation, and QT prolongation. Nortriptyline is better tolerated in older adults. SNRIs — duloxetine especially — are cleaner and carry indications for diabetic peripheral neuropathy, fibromyalgia, and chronic musculoskeletal pain. Teach patients that these are being given for pain, not because you think the pain is "in their head" — that single sentence prevents a great deal of nonadherence — and that relief takes days to weeks, unlike an analgesic.

Rounding out the toolbox: carbamazepine is first-line for trigeminal neuralgia (watch for hyponatremia, agranulocytosis, and severe skin reactions, with HLA-B*1502 screening in at-risk ancestries); corticosteroids such as dexamethasone shrink the inflammation around a compressed nerve, a bone metastasis, or a brain tumor; a lidocaine 5% patch numbs a localized area (postherpetic neuralgia) with almost no systemic exposure; capsaicin depletes substance P; bisphosphonates ease metastatic bone pain; low-dose ketamine blocks NMDA receptors for opioid-refractory and neuropathic pain; and muscle relaxants (cyclobenzaprine, tizanidine, baclofen) treat spasm-driven pain — with the standing warning that abrupt withdrawal of intrathecal baclofen is a life-threatening emergency.

Migraine: abort it or prevent it — two entirely different jobs

Migraine is not "a bad headache." It is a neurovascular event: trigeminal nerve activation releases calcitonin gene-related peptide (CGRP) and other neuropeptides, cranial vessels dilate, sterile perivascular inflammation follows, and the result is throbbing unilateral pain with nausea, photophobia, and phonophobia, sometimes preceded by aura. Drugs split cleanly into two jobs, and confusing them is the most common patient error you will correct.

Abortive (acute) therapy stops an attack in progress. Triptans — sumatriptan is the prototype — are serotonin 5-HT1B/1D agonists: they constrict the dilated cranial vessels, suppress the release of inflammatory neuropeptides, and quiet trigeminal transmission. The teaching is simple and non-negotiable: take it at the first sign of the headache, because a triptan given late into a full attack works poorly. Available oral, nasal, and subcutaneous — the injection matters when vomiting makes a pill useless. Expect flushing, tingling, warmth, and the classic "triptan sensations" of chest, neck, or jaw tightness. That chest tightness is usually benign, but because triptans constrict blood vessels, they are contraindicated in coronary artery disease, prior MI or stroke, uncontrolled hypertension, peripheral vascular disease, and hemiplegic or basilar migraine, and must not be combined with an ergot within 24 hours. Ergotamine and dihydroergotamine are older, less selective vasoconstrictors — more nausea, risk of ergotism, contraindicated in pregnancy and with strong CYP3A4 inhibitors. Newer options avoid vasoconstriction entirely: the gepants (ubrogepant, rimegepant) block the CGRP receptor and are usable in patients with cardiovascular disease, and the ditan lasmiditan targets 5-HT1F without constricting vessels but causes enough dizziness that patients must not drive for 8 hours.

Preventive (prophylactic) therapy is taken every day whether or not there is a headache, and is considered when attacks are frequent, disabling, or abortives are failing. The mainstays are propranolol or metoprolol, topiramate (paresthesias, cognitive fog, weight loss, kidney stones, teratogenic), valproate (contraindicated in pregnancy), amitriptyline, the CGRP monoclonal antibodies (erenumab, fremanezumab, galcanezumab, eptinezumab — monthly or quarterly injections), and onabotulinumtoxinA for chronic migraine. Set expectations: prevention is judged over 8–12 weeks and success means fewer, milder attacks, not zero.

One more thing to teach every migraine patient: medication overuse headache. Using acute treatments too often — roughly more than 10–15 days a month, depending on the drug — produces a chronic daily headache driven by the treatment itself. A patient reaching for a triptan or a combination analgesic most days needs prevention, not a bigger acute prescription.

Section 5Substance use and withdrawal

The words come first

Substances of misuse are chemically unrelated to each other, but they converge on one circuit: the mesolimbic dopamine pathway that evolved to make food, safety, and connection feel worth repeating. Drugs flood it far harder than any natural reward, and with repetition the circuit rewires — the drug feels necessary and everything else feels flat. That is a description of a brain, not a character.

Which is why the language matters clinically, not just politely. Say a person with a substance use disorder, not "an addict"; a positive toxicology screen, not "dirty urine"; a person in recovery, not "clean." Patients hear stigma and stop disclosing, and a patient who will not tell you what they took is a patient you cannot keep alive. Carry Section 3's distinctions with you: tolerance (needs more for the same effect) and physical dependence (withdrawal on stopping) are pharmacology and happen to anyone; substance use disorder is compulsive use despite harm.

Alcohol: the withdrawal that kills

Alcohol is a CNS depressant that enhances inhibitory GABA-A transmission and blocks excitatory NMDA receptors. Chronically, the brain compensates by downregulating GABA and upregulating NMDA. Remove the alcohol and that compensation is suddenly unopposed — the brain is left in a state of raw excitation. That is the whole pathophysiology of alcohol withdrawal, and it is why it can be fatal.

The timeline is worth memorizing. Roughly 6–24 hours after the last drink: tremor, anxiety, insomnia, nausea, diaphoresis, tachycardia, hypertension. 12–24 hours: alcoholic hallucinosis — often visual, with the sensorium otherwise intact. 12–48 hours: withdrawal seizures, generalized tonic-clonic. 48–96 hours: delirium tremens — global confusion, agitation, hallucinations, fever, and severe autonomic instability, with real mortality even when treated. Use a validated tool (CIWA-Ar) and dose symptom-triggered.

Treatment substitutes a safer drug for the same receptor: benzodiazepines (lorazepam, diazepam, chlordiazepoxide) restore GABA tone and prevent seizures and DTs. Lorazepam is often chosen in liver disease because its metabolism is less affected. Add thiamine — and here is a rule to make reflexive: thiamine before glucose. A thiamine-depleted brain given a glucose load can be tipped into Wernicke encephalopathy (confusion, ataxia, ophthalmoplegia), which if missed becomes irreversible Korsakoff syndrome. Also replace folate and magnesium, and correct electrolytes.

For long-term treatment: naltrexone (opioid antagonist — blunts craving and reward; oral or monthly IM; requires an opioid-free interval and caution in hepatic disease), acamprosate (helps restore glutamate/GABA balance; renally dosed — useful when the liver is compromised), and disulfiram (blocks aldehyde dehydrogenase, so drinking causes an intolerable acetaldehyde reaction — flushing, throbbing headache, vomiting, tachycardia, hypotension). Disulfiram teaching is exhaustive and non-optional: no alcohol in anything — mouthwash, cough syrup, sauces, vinegars, aftershave, hand sanitizer — for at least 14 days after the last dose.

Opioids, sedatives, stimulants, nicotine

Opioid withdrawal is the mirror image of alcohol's: it is miserable but rarely lethal in an otherwise healthy adult. Yawning, lacrimation, rhinorrhea, mydriasis (the opposite of overdose's pinpoint pupils), piloerection — the gooseflesh that gives us "cold turkey" — myalgias, abdominal cramping, vomiting, diarrhea, restlessness, and profound anxiety. Score it with COWS. But do not let "not lethal" become "not important": untreated withdrawal is precisely what drives people back to use, and after even a short abstinence their tolerance has fallen — so the old dose is now a fatal dose. Withdrawal treated badly kills people at one remove.

The treatments are medications for opioid use disorder, and they are the evidence-based standard, not a moral failure: buprenorphine (usually with naloxone as an abuse deterrent) — and remember the partial-agonist trap from Section 3: give it too early and it displaces the full agonist and precipitates withdrawal, so you wait for objective moderate withdrawal; methadone, effective and dispensed for OUD through certified programs; naltrexone (extended-release IM) after a 7–10 day opioid-free interval; and clonidine or lofexidine, alpha-2 agonists that blunt the autonomic storm (watch for hypotension and sedation) without touching craving. And for every patient at risk — and their family — take-home naloxone with real teaching, not a pamphlet.

Sedative-hypnotics (benzodiazepines, barbiturates) behave like alcohol, because they share the GABA receptor: withdrawal can be life-threatening, with seizures and delirium. Never discontinue a chronic benzodiazepine abruptly — taper slowly. Flumazenil is the benzodiazepine antagonist, but it is used sparingly and rarely in chronic users or mixed overdose, because stripping GABA support can precipitate refractory seizures.

Stimulants (cocaine, methamphetamine, prescription amphetamines) do the opposite: sympathetic overdrive — hypertension, tachycardia, hyperthermia, dilated pupils, agitation, paranoia and psychosis, chest pain, myocardial infarction, stroke, and seizures. For cocaine-associated chest pain the classic teaching is benzodiazepines and nitroglycerin, and to avoid an unopposed beta blocker (blocking beta while alpha runs free can worsen coronary vasoconstriction and hypertension). Stimulant withdrawal is the "crash": not physically dangerous, but dysphoria, hypersomnia, hyperphagia, vivid dreams, agitation, ferocious craving, and depression with real suicide risk — screen for it. There is no approved pharmacotherapy; behavioral treatment and contingency management are what work.

Nicotine is the substance that drives the deadliest habit in this section. Nicotine itself is what causes the dependence; the body count comes from the combustion products inhaled alongside it, which is why smoking kills more people than every other drug here combined. Withdrawal — irritability, anxiety, poor concentration, increased appetite, craving — peaks in the first week. Treatment: nicotine replacement (a long-acting patch for the baseline plus a short-acting gum, lozenge, or inhaler for breakthrough craving is the most effective NRT strategy), varenicline (a partial agonist at the nicotinic receptor: it satisfies enough to blunt withdrawal while blocking the reward of a cigarette — expect nausea, vivid dreams, insomnia), and bupropion (which lowers the seizure threshold — contraindicated in seizure disorders and in eating disorders). Cannabis deserves a mention too: withdrawal is real if mild (irritability, insomnia, appetite loss), and cannabinoid hyperemesis syndrome — cyclic vomiting relieved by hot showers — shows up in emergency departments regularly.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Adjuvant analgesic

A drug whose primary indication is not pain but which relieves it in certain conditions — gabapentinoids, TCAs, SNRIs, corticosteroids; first-line for neuropathic pain.

Agonist-antagonist

An opioid that activates kappa receptors while blocking mu (nalbuphine, butorphanol); has a ceiling on respiratory depression and can precipitate withdrawal in opioid-dependent patients.

Breakthrough pain

A transient flare of pain over an otherwise controlled baseline, treated with a short-acting opioid in addition to the long-acting regimen.

Ceiling effect

The dose beyond which more drug produces no further effect. With non-opioids the ceiling is on analgesia while toxicity keeps climbing, so more milligrams buy only harm; with partial agonists such as buprenorphine the ceiling is on respiratory depression, which is a safety advantage.

CIWA-Ar

A validated scoring tool for alcohol withdrawal severity used to trigger benzodiazepine dosing.

COWS

The Clinical Opiate Withdrawal Scale, used to grade opioid withdrawal — including the moderate threshold required before starting buprenorphine.

Cyclooxygenase (COX)

The enzyme that makes prostaglandins; COX-1 protects stomach, kidney, and platelets, COX-2 drives inflammation, and NSAIDs inhibit one or both.

Delirium tremens

Severe alcohol withdrawal at roughly 48–96 hours — confusion, hallucinations, fever, autonomic instability; a medical emergency with real mortality.

Endorphin

An endogenous opioid peptide released as part of descending pain modulation; acts at the same receptors as morphine.

Gate control theory

The idea that stimulating large touch fibers partially closes a dorsal-horn "gate" on pain transmission — the rationale for massage, heat, cold, and TENS.

Mu receptor

The opioid receptor responsible for analgesia, euphoria, sedation, respiratory depression, constipation, miosis, and physical dependence — analgesia and respiratory depression come from the same receptor, which is why they cannot be separated.

Multimodal analgesia

Combining drugs with different mechanisms plus non-drug measures so each contributes at a lower, safer dose; the basis of opioid sparing.

NAPQI

The toxic acetaminophen metabolite normally neutralized by glutathione; in overdose it accumulates and causes hepatic necrosis.

Neuropathic pain

Pain from damaged or misfiring nerves — burning, shooting, electric — that responds poorly to opioids and NSAIDs and well to adjuvants.

Nociception

The physiologic detection and transmission of a noxious stimulus: transduction, transmission, perception, and modulation.

Nociceptive pain

Pain from actual tissue damage sensed by intact nerves; subdivided into somatic and visceral.

Opioid-induced constipation

Slowed gut motility from mu receptor activation; the one opioid effect to which tolerance does not develop, requiring a scheduled stimulant laxative.

Physical dependence

Physiologic adaptation such that abrupt cessation or an antagonist produces withdrawal; expected with sustained opioid therapy and not the same as addiction.

Pseudoaddiction

Drug-seeking behavior caused by inadequate pain treatment that resolves once the pain is adequately controlled.

Reye syndrome

Acute encephalopathy with fatty liver linked to aspirin use in children and teens during a viral illness; the reason aspirin is avoided in that group.

Substance use disorder

A diagnosable pattern of compulsive use, craving, loss of control, and continued use despite harm — distinct from tolerance and physical dependence.

Tolerance

A diminishing effect from the same dose over time, requiring dose escalation; expected pharmacology, not addiction.

Mental Health, Antiepileptic & Anesthetic Drugs

Every drug in this chapter works in the same place: the tiny gap between two nerve cells. Speed a chemical signal up, slow it down, or silence it entirely, and you change mood, thought, movement, awareness, and pain. That is enormous power, and it comes with enormous responsibility — these are the drugs that cause serotonin syndrome, that stop a seizure, that stop breathing. This chapter walks you from the synapse outward: what the neurotransmitters do, what each drug class does to them, and what you — the nurse holding the syringe and watching the monitor — do about it.

Section 1Neurotransmitters & drug targets

The synapse is the whole story

Neurons do not touch. Where one ends and the next begins there is a microscopic gap — the synaptic cleft — and the message crosses it as a puff of chemical called a neurotransmitter. The sending (presynaptic) neuron packages the transmitter into vesicles, dumps them into the cleft when an electrical impulse arrives, and the transmitter drifts across and binds receptors on the receiving (postsynaptic) neuron. Then it must be cleared, or the signal never turns off. Clearance happens two ways: the transmitter is vacuumed back into the sending neuron by a reuptake pump, or it is chopped up by an enzyme.

That handful of steps is your entire map of psychiatric pharmacology. There is no drug that "fixes depression." There are drugs that block a reuptake pump, drugs that inhibit a degrading enzyme, drugs that occupy a receptor so the real transmitter cannot, and drugs that make a receptor more responsive than it would otherwise be. Once you know which step a drug touches, its effects — wanted and unwanted — stop being a list to memorize and start being something you can reason out.

Two vocabulary words earn their keep here. An agonist binds a receptor and turns it on, imitating the natural transmitter. An antagonist binds the receptor and turns nothing on — it just sits there, blocking the real transmitter from docking. Most antipsychotics are antagonists. Most antidepressants are neither: they leave more transmitter in the cleft by blocking its removal.

The four transmitters that matter most

Serotonin (5-HT) is the mood, sleep, appetite, and anxiety transmitter — and, importantly, it is not confined to the brain. Most of the body's serotonin lives in the gut, which is exactly why serotonergic drugs cause nausea and diarrhea, and why too much serotonin produces the gastrointestinal storm you will read about shortly. Dopamine runs four different circuits: reward and motivation, fine motor control (the basal nuclei), hormone regulation (it suppresses prolactin), and a brainstem trigger zone for vomiting. Block dopamine and you will hit all four, which is why antipsychotics cause both the effect you want and the movement disorders you do not.

Norepinephrine (NE) is alertness, drive, energy, and blood pressure — the internal accelerator. Boost it and depressed patients gain energy; boost it too much and they get tachycardic, tremulous, and hypertensive. GABA (gamma-aminobutyric acid) is the brain's brake pedal, the main inhibitory transmitter. When GABA binds its receptor, chloride flows into the neuron and makes it harder to fire. Nearly every sedative, anxiolytic, many antiepileptics, and most general anesthetics work by pushing on that brake — which is also why they all stack on top of one another and why combining them can stop a patient's breathing.

Notice that last row. Acetylcholine is not usually the target of these drugs — it is the innocent bystander. Older antidepressants and older antipsychotics block acetylcholine receptors by accident, and that accident produces the anticholinergic effects your patient will actually complain about: the cotton mouth, the constipation, the inability to urinate, and in an older adult, the confusion that gets mistaken for dementia.

Section 2Antidepressants & mood stabilizers

Four generations of the same idea

All four antidepressant classes raise the amount of serotonin and/or norepinephrine hanging around in the synapse. They differ almost entirely in how selectively they do it — and selectivity is safety. The classes came in the order they did because each generation learned to hit the target and miss the bystanders.

SSRIs (selective serotonin reuptake inhibitors) — fluoxetine, sertraline, escitalopram, paroxetine, citalopram — block only the serotonin pump. They are first-line because they are hard to die from, not because they work better than the old drugs. Expect nausea and headache in the first week (the gut is full of serotonin receptors), insomnia or drowsiness, and, in the long run, sexual dysfunction — the single most common reason patients quietly stop taking them. Ask about it directly and without embarrassment; a patient who feels able to say "this is ruining my sex life" is a patient who can be switched to something else instead of relapsing in silence.

SNRIs (venlafaxine, duloxetine) block the serotonin pump and the norepinephrine pump. That second target adds energy and blunts neuropathic pain — duloxetine is genuinely useful in diabetic neuropathy and fibromyalgia — but it also adds hypertension. Check a blood pressure at every visit on venlafaxine.

TCAs (amitriptyline, nortriptyline, imipramine) block both pumps too, but they also blunder into histamine, acetylcholine, and alpha-1 receptors. So: sedation, anticholinergic misery, and orthostatic hypotension. Their real danger is cardiac — in overdose they block sodium channels in the heart, widen the QRS, and cause fatal dysrhythmias. A widening QRS is the signal to act, and the treatment is IV sodium bicarbonate, which overcomes the sodium-channel blockade. A one-week supply can kill, which makes them a poor choice for a patient at risk of suicide. MAOIs (phenelzine, tranylcypromine, selegiline) take the enzyme route: they disable monoamine oxidase, the enzyme that destroys serotonin, norepinephrine, and dopamine. Effective, and hemmed in by a diet.

The MAOI diet, and why it is not optional

Monoamine oxidase in your gut wall exists to destroy tyramine, an amine in aged and fermented food. Disable that enzyme and tyramine walks into the bloodstream, floods nerve terminals, and dumps stored norepinephrine all at once. The result is a hypertensive crisis: a pounding occipital headache, blood pressure that can exceed 180/120, stiff neck, sweating, and the real possibility of a stroke. Teach the list — aged cheeses, cured and smoked meats, tap and craft beer, red wine, soy sauce, sauerkraut, fava beans, overripe fruit, yeast extracts — and teach it as though it were an allergy list, because functionally it is.

The two-week lie, and the black box

Every antidepressant raises transmitter levels within hours, yet mood does not lift for two to six weeks — the therapeutic effect requires slow receptor adaptation downstream. Patients do not know this. They take a pill for eight days, feel nothing but nausea, and quit. Telling them up front — "the side effects come first and fade, the benefit comes later and lasts" — is one of the highest-yield things a nurse says all shift.

The gap is also dangerous. Antidepressants carry a boxed warning for increased suicidal thinking in patients under 25, and there is a mechanical reason the risk is front-loaded: energy returns before mood does. A profoundly depressed patient may lack the drive to act on suicidal thoughts; two weeks in, the drive is back and the hopelessness is not. Assess suicidality at every contact during that window, not just at intake.

Two more habits. Do not stop an SSRI or SNRI abruptly — discontinuation syndrome (dizziness, flu-like aches, electric-shock "brain zaps," irritability) is miserable and easily avoided by tapering; paroxetine and venlafaxine are the worst offenders because of short half-lives. And screen for bipolar disorder before starting: an antidepressant given alone to a patient with undiagnosed bipolar disorder can flip them into mania.

Serotonin syndrome

Serotonin syndrome is too much serotonergic activity, usually from combining agents — an SSRI plus tramadol, plus triptans for migraine, plus linezolid, plus St. John's wort, plus an MAOI. It arrives fast, typically within hours of the new drug or dose increase, and it is recognized by a triad: mental status change (agitation, confusion), autonomic instability (fever, tachycardia, diaphoresis, diarrhea), and neuromuscular hyperactivity (tremor, hyperreflexia, and clonus — the most specific sign, often worst in the legs). Stop the serotonergic drugs, call the provider, support with cooling and IV fluids, benzodiazepines for agitation and rigidity, and cyproheptadine as the serotonin-blocking antidote in severe cases.

Lithium levels track a narrow road: 0.6–1.2 mEq/L for maintenance, with anything over 1.5 mEq/L counting as toxic and over 2.0 mEq/L a medical emergency. Draw levels as troughs, 12 hours after the evening dose. Expected effects at therapeutic levels are a fine hand tremor, mild thirst, and increased urination. Early toxicity is GI — nausea, vomiting, diarrhea — plus a coarse tremor and slurred speech; later comes ataxia, confusion, seizures, and cardiovascular collapse. There is no antidote; treatment is fluids and, at high levels, hemodialysis. Because lithium is cleared renally and affects the thyroid, baseline and periodic renal function, TSH, and pregnancy status belong in every monitoring plan. Valproate and lamotrigine also serve as mood stabilizers — both carry their own warnings, covered next section over.

Section 3Antipsychotics & anxiolytics

Typical antipsychotics: dopamine blockade, and the price of it

Typical (first-generation) antipsychotics — haloperidol, fluphenazine, chlorpromazine — are dopamine D2 antagonists, and they are good at exactly one thing: the positive symptoms of psychosis. Hallucinations, delusions, and disorganized thought are the "added" symptoms, and blocking dopamine strips them away. What these drugs barely touch are the negative symptoms — the flat affect, poverty of speech, social withdrawal, and lost motivation. That distinction matters at the bedside, because a patient whose voices are gone but who still cannot get out of bed is not treatment-resistant; they are inadequately treated.

The price is movement. Dopamine blockade in the basal nuclei — the circuit in the reference figure above — produces extrapyramidal symptoms (EPS), and they arrive in a predictable order that is worth knowing because the timing tells you what you are looking at.

Two other consequences follow straight from the dopamine map. Dopamine normally suppresses prolactin, so blocking it raises prolactin: expect galactorrhea, amenorrhea, gynecomastia, and sexual dysfunction — embarrassing effects that patients hide and then stop the drug over. And neuroleptic malignant syndrome (NMS) is the rare, life-threatening reaction: fever (often above 40 °C), lead-pipe rigidity, altered consciousness, autonomic instability, and a sky-high creatine kinase from muscle breakdown. Stop the antipsychotic, cool aggressively, hydrate, and expect dantrolene or bromocriptine. NMS and serotonin syndrome look alike; the tell is that NMS is rigid and slow (days, lead-pipe rigidity, hyporeflexia), while serotonin syndrome is fast and jumpy (hours, clonus, hyperreflexia, diarrhea).

Atypicals: fewer movements, more metabolism

Atypical (second-generation) antipsychotics — risperidone, olanzapine, quetiapine, aripiprazole, ziprasidone, clozapine — block dopamine D2 and serotonin 5-HT2A receptors (aripiprazole is the exception: it is a D2 partial agonist, which is why it is less sedating and rarely raises prolactin), and that second action buys them two advantages: less EPS and some genuine effect on negative symptoms. They did not, however, come free. They traded movement problems for metabolic syndrome: weight gain, new-onset type 2 diabetes, and dyslipidemia. Olanzapine and clozapine are the worst; ziprasidone and aripiprazole are gentler. That means metabolic monitoring is nursing work — baseline and periodic weight, waist circumference, blood pressure, fasting glucose or A1C, and a lipid panel.

Clozapine is the one to know cold. It is the most effective antipsychotic that exists, reserved for treatment-resistant schizophrenia, and it can cause severe neutropenia (agranulocytosis) — which is why it is dispensed only through a REMS program with mandatory absolute neutrophil count monitoring. A fever or a sore throat in a patient on clozapine is not a cold until an ANC proves it. It also causes myocarditis, seizures at higher doses, severe constipation that can progress to ileus, and, oddly, drooling. All antipsychotics carry a boxed warning against use in elderly patients with dementia-related psychosis because of increased mortality.

Benzodiazepines and the GABA brake

Benzodiazepines — lorazepam, diazepam, alprazolam, midazolam, clonazepam — do not open the chloride channel themselves. They are positive allosteric modulators: they sit alongside the GABA receptor and make GABA's own effect stronger, increasing how frequently the chloride channel opens when GABA binds. That mechanism has a built-in ceiling, and it is the reason a benzodiazepine alone is fairly hard to die from — without GABA present, the drug does nothing. Add an opioid or alcohol, which push on the same brake by other routes, and the ceiling disappears. Most benzodiazepine deaths are combination deaths.

They are excellent short-term drugs: rapid anxiety relief, sedation, muscle relaxation, seizure termination, and alcohol-withdrawal management. They are poor long-term drugs: tolerance develops, dependence follows, and abrupt withdrawal after chronic use can cause seizures and death — a benzodiazepine taper is not a courtesy, it is a safety measure. In older adults they are on the Beers list for a reason: falls, hip fractures, and confusion. Flumazenil reverses them, but use it cautiously — in a chronic user or a mixed overdose it can precipitate intractable seizures. The safer non-benzodiazepine option for chronic anxiety is buspirone: no sedation, no dependence, no reversal needed — but it takes weeks to work and is useless as a rescue.

Section 4Antiepileptic drugs

Three ways to stop a seizure — and one more

A seizure is a neuronal riot: a population of neurons firing too fast, too synchronously, and spreading that firing to their neighbors. There are three fundamental ways a drug can quiet it, and most antiepileptic drugs (AEDs) — the word anticonvulsant is used interchangeably — use at least one of them. A smaller group, led by the drug you will see ordered most often, works by a fourth route entirely.

Slow the sodium channels. A neuron cannot fire without opening voltage-gated sodium channels, and after each firing those channels need a moment to reset. Phenytoin, carbamazepine, lamotrigine, and others prolong that inactive state, so a neuron can still fire at a normal rate but cannot fire at a runaway rate. That is elegant: normal traffic passes, the riot does not. Slow the calcium channels. The T-type calcium channels in the thalamus drive the rhythmic 3-per-second discharge of absence seizures; ethosuximide blocks them, which is why it works for absence seizures and nothing else. Boost GABA. More inhibition raises the seizure threshold for the whole brain — the mechanism of benzodiazepines, phenobarbital, and part of what valproate does.

And then the fourth route, which does not fit the channel-and-brake framework at all: quiet the release itself. Levetiracetam and its relative brivaracetam bind synaptic vesicle protein 2A (SV2A) on the presynaptic vesicle and blunt how much transmitter is dumped into the cleft in the first place. Do not file this away as an oddity — levetiracetam is one of the most commonly ordered broad-spectrum AEDs on the unit, so the framework you carry has to have a place for it. Say it as "three channel-and-GABA mechanisms, plus SV2A," and every drug in the table below has a home.

Two nursing consequences fall out of this. First, most AEDs are broad brakes on brain excitability, so sedation, dizziness, and ataxia are class effects, and fall precautions and a no-driving-until-stable conversation belong in the plan. Second, AEDs are prevention, not rescue — missed doses are the single most common reason a controlled patient seizes. Never abruptly discontinue an AED; abrupt withdrawal can trigger status epilepticus in a patient with epilepsy, and withdrawal seizures even in a patient taking the drug for pain or mood who has never had a seizure in their life.

Monitoring, teaching, and the seizure itself

Phenytoin and valproic acid have narrow therapeutic ranges and get serum levels; lamotrigine and levetiracetam generally do not. Draw levels as troughs, just before the next dose, and remember that phenytoin is heavily protein-bound — in a patient with low albumin, the total level can look normal while the free (active) drug is toxic. If the number says fine and the patient has nystagmus, ataxia, and slurred speech, believe the patient.

Teaching carries real weight here. Take doses at the same times every day. Do not stop, even if seizure-free for years, without a supervised taper. Carry medical identification. Know your state's driving restrictions. Alcohol lowers the seizure threshold and stacks sedation. Many AEDs — carbamazepine, phenytoin, phenobarbital — are enzyme inducers that can render oral contraceptives ineffective, and valproate and carbamazepine are teratogenic, so contraception counseling is not optional for anyone of childbearing potential. AEDs also carry a class warning for suicidal thoughts; screen for mood changes at follow-up.

And when a seizure happens: your job is not to stop it with your hands. Stay, protect the head, turn the patient to the side, loosen tight clothing, clear the area, time it, and never force anything into the mouth. A generalized seizure lasting more than five minutes, or repeated seizures without a return to baseline, is status epilepticus — a true emergency treated with IV benzodiazepines first, then a loading agent such as fosphenytoin, valproate, or levetiracetam.

Section 5Anesthetics

Two entirely different jobs

The words sound related, but general and local anesthesia are opposites in strategy. General anesthesia takes away the brain: unconsciousness, amnesia, analgesia, and immobility, delivered systemically, with the patient's protective reflexes — including breathing — deliberately abolished. Local anesthesia leaves the brain entirely alone and cuts the wire instead: the drug blocks sodium channels in a specific nerve so the pain signal never leaves the tissue. The patient is awake and knows exactly what is happening. One takes the receiver offline; the other cuts the phone line.

Modern general anesthesia is almost never one drug — it is balanced anesthesia, a deliberate combination: an IV induction agent to go to sleep fast, an inhaled agent to stay asleep, an opioid for pain, and a neuromuscular blocker for immobility. Combining lets each drug be given at a lower, safer dose. Inhaled agents (sevoflurane, desflurane, isoflurane, nitrous oxide) are titrated breath by breath and eliminated by the lungs. IV agents include propofol — fast, smooth, antiemetic, and a potent respiratory depressant and vasodilator; ketamine — a dissociative that preserves airway reflexes and respiratory drive, valuable in trauma, with emergence delirium as its signature; etomidate — hemodynamically kind, so favored in unstable patients, but it suppresses adrenal function; and midazolam — for anxiolysis and amnesia.

Neuromuscular blockers deserve special fear. Succinylcholine (depolarizing, ultra-short, with fasciculations, hyperkalemia risk, and a link to malignant hyperthermia) and rocuronium or vecuronium (non-depolarizing, reversed with neostigmine or sugammadex) cause paralysis without any sedation or analgesia whatsoever. A paralyzed patient who is not adequately sedated is fully awake, in pain, and unable to signal it. These are high-alert drugs, stored separately, and given only where an airway can be secured immediately.

The stages of anesthesia

Guedel's four stages were described in the era of ether, when induction was slow enough to watch. Modern agents blow through the first three in under a minute — but the stages are still taught because they name what you are watching for, and because Stage II is where a patient can be hurt.

Emergence reverses the sequence, so the patient passes back through Stage II on the way out — which is why the PACU is quiet, why side-lying with suction at hand is standard, and why an emerging patient who thrashes is not "being difficult." Two emergencies live in this territory. Malignant hyperthermia is a genetic reaction to volatile agents and succinylcholine: uncontrolled calcium release in muscle produces masseter rigidity, a fast-rising end-tidal CO₂ (the earliest sign), rigidity, tachycardia, and a temperature that climbs alarmingly — treated with dantrolene, immediate cessation of the trigger, cooling, and treatment of hyperkalemia. Ask about family history of anesthesia problems before surgery; it is a question that saves lives. And aspiration is why NPO status exists — anesthesia strips the gag reflex.

Local anesthetics: the wire cut

Locals come in two chemical families and the difference is clinical. Esters (procaine, benzocaine, tetracaine) are broken down in plasma and cause more allergic reactions; benzocaine sprays also cause methemoglobinemia — suspect it when a patient is cyanotic with a normal PaO₂ and chocolate-brown blood, and treat with methylene blue. Amides (lidocaine, bupivacaine, ropivacaine — note the tell-tale second "i" in the name) are metabolized by the liver and rarely cause true allergy. They are given topically, by local infiltration, as a nerve block, epidurally, or spinally.

Epinephrine is often added to a local. It constricts vessels, which keeps the drug where you put it: longer block, less bleeding, less systemic absorption. The old teaching to avoid epinephrine-containing locals in fingers, toes, nose, ears, and penis has been substantially revised for the digits by modern evidence, but it remains a caution worth knowing and honoring wherever facility policy says so.

The danger of locals is systemic absorption — too much drug, or an accidental intravascular injection. Local anesthetic systemic toxicity (LAST) announces itself in the brain first: circumoral (around-the-mouth) numbness, a metallic taste, tinnitus, dizziness, and agitation, then seizures, then cardiac arrest. Bupivacaine is the most cardiotoxic and can go straight to arrest. Treatment is airway support, benzodiazepines for seizures, and IV lipid emulsion — which every unit doing blocks keeps at hand. After a spinal or epidural, watch for hypotension from sympathetic blockade, monitor the level of the block, keep the patient flat per protocol, and remember that the block recedes in the reverse of how it came on: the level drops from the top down, so the highest dermatomes wake up first and the toes come back last. A patient with moving toes and a wearing-off block is exactly the patient who tries to stand and falls — sensation and motor strength in the feet are the last things to return, and the fall risk lasts until they are fully back.

ReferenceWords worth knowing

The vocabulary of this chapter is the vocabulary of the report you will give and the order you will question — skim it now, and come back whenever a term stops you.

Agonist

A drug that binds a receptor and activates it, imitating the body's own transmitter.

Akathisia

An extrapyramidal effect of intolerable inner restlessness and an inability to sit still; commonly mistaken for worsening psychosis.

Antagonist

A drug that binds a receptor without activating it, blocking the natural transmitter from acting.

Antiepileptic drug (AED)

A drug that raises the seizure threshold — most by slowing sodium or calcium channels or enhancing GABA, and some (levetiracetam, brivaracetam) by binding synaptic vesicle protein 2A to reduce transmitter release; also called an anticonvulsant.

Balanced anesthesia

Combining an induction agent, an inhaled agent, an opioid, and a neuromuscular blocker so each can be given at a lower, safer dose.

Discontinuation syndrome

Dizziness, flu-like aches, irritability, and "brain zaps" after abruptly stopping an SSRI or SNRI; prevented by tapering.

Dystonia

Sudden sustained muscle spasm — neck twisting, oculogyric crisis, or laryngospasm — occurring within hours to days of an antipsychotic; an emergency.

Extrapyramidal symptoms (EPS)

Movement disorders caused by dopamine blockade in the basal nuclei: dystonia, akathisia, parkinsonism, and tardive dyskinesia.

Flumazenil

The benzodiazepine reversal agent; used cautiously, as it can precipitate seizures in chronic users or mixed overdoses.

GABA

Gamma-aminobutyric acid, the brain's main inhibitory neurotransmitter; opening its chloride channel makes neurons harder to fire.

Local anesthetic systemic toxicity (LAST)

Toxicity from systemic absorption of a local anesthetic: circumoral numbness, metallic taste, and tinnitus progressing to seizures and cardiac arrest; treated with IV lipid emulsion.

Malignant hyperthermia

A genetic, life-threatening reaction to volatile anesthetics or succinylcholine causing rigidity, rising end-tidal CO₂, and hyperthermia; treated with dantrolene.

Monoamine oxidase (MAO)

The enzyme that degrades serotonin, norepinephrine, and dopamine — and dietary tyramine in the gut wall.

Negative symptoms

The "subtracted" symptoms of psychosis — flat affect, poverty of speech, withdrawal, lost motivation — poorly treated by typical antipsychotics.

Neuroleptic malignant syndrome (NMS)

A rare antipsychotic reaction of high fever, lead-pipe rigidity, altered consciousness, autonomic instability, and elevated creatine kinase.

Neuromuscular blocker

A high-alert drug that paralyzes skeletal muscle without producing any sedation or analgesia; requires a secured airway.

Positive symptoms

The "added" symptoms of psychosis — hallucinations, delusions, disorganized thought — that respond best to dopamine blockade.

Reuptake pump

The transporter that vacuums a neurotransmitter back into the presynaptic neuron; the target of SSRIs, SNRIs, and TCAs.

Serotonin syndrome

Excess serotonergic activity producing mental status change, autonomic instability, and neuromuscular hyperactivity with clonus; treated by stopping the agents, supportive care, and cyproheptadine.

Status epilepticus

A seizure lasting more than five minutes, or repeated seizures without a return to baseline; treated first with an IV benzodiazepine.

Tardive dyskinesia

Late-onset involuntary lip-smacking, tongue-thrusting, and grimacing after months to years of dopamine blockade; often irreversible.

Tyramine

An amine in aged, fermented, and cured foods that triggers a hypertensive crisis in a patient taking an MAOI.

Bone & Skin Drugs

Bone and skin look like the quiet parts of the body — scaffolding and wrapping paper. They are neither. Bone is a living, constantly rebuilt mineral bank that the body raids whenever blood calcium dips, and skin is a barrier that fails loudly and expensively when it is burned, inflamed, or broken. The drugs in this chapter are unusually dependent on you: a bisphosphonate swallowed the wrong way can burn a hole in an esophagus, methotrexate taken daily instead of weekly can kill, and a burn cream chosen carelessly can tip a patient into metabolic acidosis. Almost nothing here is about the pill itself. It is about how it is given, what you watch, and what you teach.

Section 1Bone, calcium & vitamin D

Bone is never finished

The skeleton you have today is not the skeleton you had ten years ago. Bone is torn down and rebuilt continuously in a process called remodeling, carried out by two cell crews working in opposition. Osteoclasts are the demolition crew: they attach to a patch of bone, acidify it, and dissolve the mineral, releasing calcium into the blood. Osteoblasts are the construction crew: they lay down new collagen matrix and mineralize it. In a healthy adult the two are balanced. Tip the balance toward the clasts and bone thins; tip it toward the blasts and bone thickens.

The signal that decides the balance is worth memorizing because half the drugs in the next section act on it. Osteoblasts secrete a protein called RANK ligand (RANKL), which binds RANK receptors on osteoclast precursors and tells them to mature and start resorbing. Osteoblasts also secrete a decoy, osteoprotegerin, that mops up RANKL and shuts resorption down. Estrogen restrains RANKL — which is precisely why bone loss accelerates after menopause, when estrogen falls and the demolition crew works unsupervised.

The calcium thermostat

Serum calcium is defended within a narrow band (roughly 8.5–10.5 mg/dL total) because so much depends on it: nerve conduction, muscle contraction, clotting, and cardiac rhythm. Three hormones do the defending.

Parathyroid hormone (PTH) is the emergency responder. When calcium falls, the parathyroid glands release PTH, which pulls calcium out of bone, tells the kidney to reabsorb calcium (while dumping phosphate), and switches on the enzyme that activates vitamin D. Everything PTH does raises calcium. Vitamin D, once activated, is the absorber — it makes the gut take calcium in from food. Calcitonin, from the thyroid, is the brake: it "tones down" calcium by blocking osteoclasts. A simple way to hold it: PTH pulls calcium up, calcitonin tones it down.

Vitamin D deserves a moment because it is not really a vitamin — it is a hormone made in two steps. Skin makes cholecalciferol from sunlight, or the patient swallows cholecalciferol (D₃) or ergocalciferol (D₂). The liver then hydroxylates it to 25-hydroxyvitamin D — the storage form, and the one the lab measures when someone orders a "vitamin D level." Finally the kidney performs the activating step, producing calcitriol (1,25-dihydroxyvitamin D). That last step is the clinical punchline: a patient with advanced kidney disease cannot activate ordinary vitamin D no matter how much you give, so they are prescribed calcitriol or a related activated analog instead.

Giving calcium and vitamin D without causing harm

Calcium supplements are labeled by salt weight, but only part of that weight is usable elemental calcium. Calcium carbonate is about 40% elemental calcium — the most calcium per tablet, and cheap — but it needs stomach acid to dissolve, so it must be taken with food and it works poorly in patients on proton pump inhibitors or H₂ blockers, or after gastric surgery. Calcium citrate is only about 21% elemental (more tablets), but it dissolves without acid, so it can be taken with or without food and is the right choice for the acid-suppressed patient. Either way, the gut can only absorb roughly 500–600 mg of elemental calcium at one time, so a 1,200 mg daily target must be split into two or three doses. Constipation is the near-universal side effect; fluids, fiber, and activity are part of the teaching, not an afterthought.

Two clinical pictures should be automatic. Hypocalcemia makes nerves twitchy: numbness and tingling around the mouth and fingers, muscle cramps, positive Chvostek (facial tap) and Trousseau (cuff-induced carpal spasm) signs, tetany, laryngospasm, seizures, and a prolonged QT. Hypercalcemia makes everything sluggish — "stones, bones, groans, thrones, and psychiatric overtones": kidney stones, bone pain, nausea and constipation, polyuria, lethargy and confusion, and a shortened QT.

Section 2Osteoporosis drugs

Bisphosphonates: the first-line drugs, and the fussiest

Bisphosphonates — alendronate, risedronate, ibandronate, and IV zoledronic acid — are antiresorptive drugs. They bind tightly to the hydroxyapatite mineral of bone and sit there. When an osteoclast comes along and dissolves that patch, it swallows the drug, which poisons an enzyme (farnesyl pyrophosphate synthase) the osteoclast needs to survive. The osteoclast undergoes apoptosis. Demolition slows, the blasts keep building, and bone density climbs.

The problem is that oral bisphosphonates are absorbed miserably — well under 1% of the dose — and they are corrosive to the esophagus. That combination generates the most heavily tested administration rules in all of pharmacology, and they are not negotiable:

• Take first thing in the morning, on a completely empty stomach, before any other food, drink, or medication.
• Swallow with a full glass (6–8 oz) of plain water — not coffee, juice, mineral water, or milk. Calcium, iron, magnesium, and antacids block absorption entirely.
• Remain fully upright — sitting or standing, never lying down — for at least 30 minutes (a full 60 minutes for ibandronate).
• Wait that same interval before eating, drinking anything else, or taking other drugs.
• Do not give to a patient who cannot sit or stand upright for that long, or who has esophageal stricture, achalasia, or delayed emptying.
• Correct hypocalcemia and vitamin D deficiency first — an antiresorptive given to a calcium-depleted patient drives calcium lower.

Two rarer adverse effects earn their own teaching. Osteonecrosis of the jaw (ONJ) is exposed, non-healing jaw bone, most often after a dental extraction; the risk is highest with IV, high-dose, oncology-level therapy, and the nursing action is to arrange a dental exam and any needed extractions before therapy starts, then reinforce meticulous oral hygiene. Atypical femoral fracture is a transverse fracture of the femoral shaft after years of therapy, and it announces itself first: teach every patient that new, dull, aching thigh or groin pain must be reported immediately, because that prodrome is the window to catch it before the bone snaps.

IV zoledronic acid is once yearly, which solves adherence, but check renal function first (generally avoid if creatinine clearance is under about 35 mL/min), hydrate the patient well, and warn them about the acute phase reaction — a flu-like day or two of fever, myalgia, and headache after the first infusion, blunted by acetaminophen and unlikely to recur.

When a bisphosphonate is not the answer

Denosumab is a monoclonal antibody against RANKL — a manufactured osteoprotegerin. Given subcutaneously every 6 months, it is not cleared by the kidney, so it can be used at renal function where bisphosphonates are contraindicated — but that convenience comes with a warning. It carries a boxed warning for severe hypocalcemia in patients with advanced chronic kidney disease (including those on dialysis), so calcium and vitamin D must be repleted and serum calcium checked before each injection and monitored closely afterward in those patients. It also carries a rule that patients under-appreciate: it must not be stopped or delayed without a replacement antiresorptive, because withdrawal triggers a rebound surge of bone resorption and multiple vertebral fractures. ONJ occurs here too.

Raloxifene is a selective estrogen receptor modulator (SERM): an estrogen agonist at bone (density up) and an antagonist at breast (invasive breast cancer risk down), while sparing the uterus. Its price is estrogen's thrombotic risk — a boxed warning for venous thromboembolism and fatal stroke in women at risk. Teach that it should be stopped 72 hours before prolonged immobilization (surgery, long travel) and restarted only when fully mobile. Hot flashes and leg cramps are common.

Everything above slows demolition. Two drug groups actually build bone. Teriparatide and abaloparatide are PTH-pathway analogs, given as a daily subcutaneous injection; the trick is that intermittent PTH exposure stimulates osteoblasts, whereas the continuous exposure of hyperparathyroidism destroys bone. Watch for hypercalcemia, and warn about orthostatic hypotension with the first several doses — the patient should inject where they can sit or lie down immediately. Avoid in patients at baseline increased risk of osteosarcoma (Paget disease, prior skeletal radiation, unexplained elevated alkaline phosphatase). Romosozumab inhibits sclerostin, building bone while also slowing resorption, given monthly for 12 months only — but it carries a boxed warning for myocardial infarction, stroke, and cardiovascular death and must not be used in anyone who has had an MI or stroke within the past year.

Section 3Gout & antiarthritis drugs

Gout: put out the fire, then lower the fuel

Gout is uric acid crystallizing in a joint. Two entirely separate jobs follow, and mixing them up is the classic error. Job one is stopping the acute flare — an anti-inflammatory problem. Job two is lowering serum urate for the long run, which does nothing for today's pain and can even provoke a flare when it starts.

For the flare, three options: an NSAID (naproxen, indomethacin), a corticosteroid (oral, or injected into a single hot joint), or colchicine. Colchicine is the interesting one. It binds tubulin, wrecking the microtubules that neutrophils need in order to crawl into the joint and unleash inflammation. It has no analgesic and no urate-lowering effect at all — it simply keeps the neutrophils away. Modern dosing is low: 1.2 mg at the first hint of a flare, then 0.6 mg one hour later. The signature toxicity is gastrointestinal — nausea, vomiting, and diarrhea are the first sign of toxicity, and the instruction is to stop the drug, not push through. Colchicine is cleared by CYP3A4 and P-glycoprotein, so combining it with clarithromycin, verapamil, diltiazem, cyclosporine, or a strong azole in a patient with kidney impairment has caused fatal marrow suppression and myopathy. Note also that aspirin is avoided in gout: low doses raise urate.

For the long run, allopurinol is the anchor. It inhibits xanthine oxidase, the enzyme that manufactures uric acid, so less is produced. Start low (100 mg, less in kidney disease) and titrate slowly to a serum urate under 6 mg/dL; encourage 2–3 L of fluid daily. Because starting it mobilizes urate and can set off a flare, patients are covered with low-dose colchicine or an NSAID for the first several months. Two allopurinol facts must be reflexes: any rash means stop the drug and call immediately (allopurinol is a leading cause of Stevens–Johnson syndrome, toxic epidermal necrolysis, and DRESS), and allopurinol blocks the metabolism of azathioprine and mercaptopurine, causing life-threatening bone marrow suppression unless those doses are slashed. Febuxostat is an alternative xanthine oxidase inhibitor for allopurinol-intolerant patients, but it carries a boxed warning for cardiovascular death and is second-line. Probenecid takes the other route — it is a uricosuric, blocking urate reabsorption in the renal tubule so more is excreted; it needs decent kidney function and generous fluids, and it is avoided if the patient has a history of stones. Pegloticase, an IV enzyme that dissolves urate directly, is reserved for refractory tophaceous gout: boxed warning for anaphylaxis, and it must never be given in G6PD deficiency (hemolysis, methemoglobinemia) — so screening comes first.

DMARDs: changing the disease, not just the symptoms

Rheumatoid arthritis is not gout and it is not wear-and-tear osteoarthritis — it is an autoimmune attack on the synovium that erodes joints permanently. NSAIDs and steroids make an RA patient feel better while the joints quietly dissolve. Disease-modifying antirheumatic drugs (DMARDs) slow the disease itself, and the guiding principle is to start them early, within weeks of diagnosis, before erosion is done. They work slowly — weeks to months — which is a teaching point, because a patient who expects ibuprofen-speed relief will stop taking them.

Methotrexate is the anchor DMARD and the single most dangerous prescribing error in this chapter. At RA doses it is given once weekly. Taken daily by mistake — and this has happened, and patients have died — it produces catastrophic mucositis and pancytopenia. Confirm the weekly schedule out loud with the patient and with anyone taking a verbal order, and check that the pill bottle and the MAR say weekly. Daily folic acid (usually 1 mg, not on the methotrexate day in some regimens) blunts the mouth sores, GI upset, and marrow effects without blocking the benefit. Methotrexate carries boxed warnings for bone marrow suppression, hepatotoxicity, pulmonary toxicity, and embryo-fetal toxicity — it is contraindicated in pregnancy, and effective contraception is required for both partners. Monitor CBC, LFTs, and creatinine. Teach no alcohol, report a persistent dry cough or dyspnea (pneumonitis) and mouth ulcers (the earliest toxicity sign). Avoid trimethoprim/sulfamethoxazole, which is an additive antifolate and can produce pancytopenia. Leucovorin is the rescue agent.

Among the other conventional DMARDs, hydroxychloroquine is the gentlest — and the one with a memorable rule: it can deposit in the retina, so patients need a baseline and annual eye exam and must report changes in vision or color perception. Sulfasalazine is avoided in sulfa allergy and G6PD deficiency and turns urine orange-yellow (harmless, but tell them). Leflunomide is hepatotoxic and a potent teratogen with a very long half-life, requiring a cholestyramine washout if pregnancy occurs or is planned.

The biologic DMARDs — TNF inhibitors (etanercept, adalimumab, infliximab), plus IL-6, T-cell, and B-cell agents — are extraordinarily effective and share one governing safety idea: they take the brakes off infection. Every patient is screened for latent tuberculosis and hepatitis B before the first dose, boxed warnings cover serious infections and malignancy including lymphoma, live vaccines are contraindicated during therapy, and the drug is held during any active infection and usually around surgery. The oral JAK inhibitors (tofacitinib, baricitinib, upadacitinib) add boxed warnings for major adverse cardiovascular events, thrombosis, malignancy, and mortality.

Section 4Skin drugs

Acne: four problems, four drug jobs

Acne is not dirt. Four things go wrong in a follicle: sebum production rises (androgen-driven), the follicle lining sheds abnormally and plugs the pore, Cutibacterium acnes multiplies behind the plug, and inflammation follows. Every acne drug attacks one of those four, which is exactly why combinations work better than any single agent.

Benzoyl peroxide kills the bacteria by releasing free radicals — and crucially, bacteria do not develop resistance to it. Teach that it bleaches fabric: white towels and pillowcases, or ruined ones. Topical retinoids (tretinoin, adapalene, tazarotene) fix the plugging by normalizing follicular shedding; apply a pea-sized amount at bedtime to dry skin, expect an initial worsening and peeling for several weeks, use non-comedogenic moisturizer, and use sunscreen because they cause photosensitivity. Topical antibiotics (clindamycin, erythromycin) should essentially never be used alone — always pair with benzoyl peroxide to prevent resistance. Oral antibiotics for moderate inflammatory acne are usually doxycycline or minocycline: photosensitivity again, pill-induced esophagitis (full glass of water, stay upright), and contraindicated in pregnancy and in children under 8 (tooth staining). Hormonal options — combined oral contraceptives, spironolactone (monitor potassium) — target the androgen driver.

Isotretinoin is the only drug that hits all four mechanisms, and it is the most tightly controlled drug most nurses will ever handle. It is a severe teratogen, and dispensing runs through the iPLEDGE risk management program: patients who can become pregnant must use two forms of contraception beginning one month before, throughout, and for one month after therapy, with monthly negative pregnancy tests and monthly program authorization. There is no blood donation during therapy or for a month afterward, because a transfused unit could reach a pregnant recipient. Expected effects: cheilitis in nearly everyone (dry cracked lips), dry eyes and nose, epistaxis, myalgia, night-vision changes, elevated triglycerides, and hepatotoxicity — so monitor lipids and LFTs and teach no alcohol. Mood changes should be reported. And a hard rule: never combine isotretinoin with a tetracycline — the pair raises intracranial pressure (pseudotumor cerebri, presenting as headache, visual changes, and nausea).

Psoriasis: turning down an overdriven immune system

Psoriasis is immune-driven hyperproliferation — keratinocytes turning over in days instead of weeks, producing thick silvery plaques. Mild disease is topical: corticosteroids (the workhorse), vitamin D analogs like calcipotriene (do not exceed the weekly maximum — systemic absorption causes hypercalcemia; it is inactivated by salicylic acid, so do not layer them), tazarotene, coal tar, and calcineurin inhibitors (tacrolimus, pimecrolimus ointment) for the face and skin folds where steroids thin the skin. Moderate to severe disease escalates to phototherapy (narrowband UVB; or PUVA, where oral methoxsalen plus UVA requires UV-blocking eyewear for 24 hours after the dose) and systemic drugs: methotrexate, cyclosporine, acitretin (a retinoid, and a teratogen so persistent that pregnancy must be avoided for 3 years after and alcohol is forbidden because it regenerates a long-lived metabolite), apremilast, and the biologics — TNF inhibitors, IL-17 blockers (secukinumab, ixekizumab), and IL-23 blockers (guselkumab, risankizumab). All of the biologics carry the same TB-screening and infection precautions as in rheumatoid arthritis.

Topical corticosteroids: potency, vehicle, quantity, and time

Topical steroids are the most used and most misused drugs in dermatology, and the nursing content is four variables. Potency is ranked in classes from 1 (superpotent, e.g., clobetasol) to 7 (low, e.g., hydrocortisone 1%). Vehicle changes potency for the same molecule: ointments are the most potent because they occlude and hydrate (best for thick, dry, scaly skin), creams are middle-ground and cosmetically acceptable, and lotions, gels, solutions, and foams are for hairy areas and the scalp. Quantity is measured in the fingertip unit — the ribbon squeezed from the tip of an adult index finger to the first crease, about 0.5 g, which covers an area equal to two adult palms. Time matters because effects accumulate.

The adverse effects follow directly from what steroids do. Locally: skin atrophy, striae, telangiectasia, hypopigmentation, acneiform eruption, and tachyphylaxis (the drug stops working, so patients use more, which is the trap). Systemically, absorption is greatest where skin is thin (face, eyelids, genitals), where skin is inflamed and barrier-broken, where the surface area is large, and wherever the site is occluded. Children absorb disproportionately more because their body-surface-to-weight ratio is high. The rule set is short: lowest potency that works, thin layer, shortest duration, no occlusion unless it is ordered, and do not put a potent steroid on the face or in a skin fold.

Section 5Burns & wound agents

Why burns get topical drugs instead of IV antibiotics

A deep burn produces eschar — dead, leathery, and, most importantly, avascular. No blood supply means no delivery: an IV antibiotic cannot reach the bacteria colonizing that surface, because the drug travels in blood and the blood does not go there. So the antimicrobial is put on the wound. Systemic antibiotics in burn care are reserved for documented invasive infection or sepsis, not prophylaxis — prophylactic systemic antibiotics simply select for resistant organisms while the wound surface stays untouched.

Three classic topical agents divide the work, and each has one toxicity that defines it.

Silver sulfadiazine is the traditional workhorse: broad-spectrum, soothing, painless to apply, spread about 1/16 inch thick with a sterile gloved hand. Its defining problem is transient leukopenia, typically appearing two to three days in — so the WBC count gets checked, and a dip is usually self-limiting. It is a sulfonamide, so it is contraindicated in sulfa allergy, and it is contraindicated in infants under 2 months and in near-term pregnancy because it displaces bilirubin and risks kernicterus. It does not penetrate eschar well, and it forms a gray pseudo-eschar that must be cleaned off before reapplication.

Mafenide acetate is the one that penetrates eschar and cartilage, which makes it the agent for burned ears and noses where cartilage is at risk. Two things follow. It hurts — a real burning pain on application, so premedicate. And it is a carbonic anhydrase inhibitor, so it causes metabolic acidosis; the patient compensates by hyperventilating, and a burn patient who becomes tachypneic on mafenide is telling you their pH is falling. Monitor acid-base status and watch the respiratory rate.

Silver nitrate 0.5% solution is applied on wet dressings that must be kept continuously moist (drying concentrates it into a caustic). It stains everything — skin, linens, walls — black or gray, which is alarming but harmless. Its real hazard is that it leaches electrolytes out of the wound: hyponatremia and hypochloremia, plus a risk of methemoglobinemia. Monitor electrolytes.

Getting the dead tissue off

Nothing granulates under slough. Debridement is the removal of nonviable tissue, and it comes in flavors. Autolytic debridement uses the body's own enzymes trapped under a moisture-retentive dressing (hydrogel, hydrocolloid) — painless and selective, but slow, and not for infected wounds. Enzymatic debridement uses collagenase, applied daily; remember it is destroyed by silver and iodine products, so those two cannot share a wound bed. Mechanical debridement — the old wet-to-dry gauze — is nonselective and painful: it rips out healthy granulation along with the slough, and it has largely been abandoned for exactly that reason. Sharp/surgical debridement is fastest and is the standard for extensive burns. Biologic (larval) debridement is a real, occasionally used option for chronic wounds.

What actually heals a wound

The single most important idea in modern wound care is that a moist wound heals faster than a dry one. Old teaching let wounds "air out" and form a scab; we now know epithelial cells migrate across a moist bed and stall at a dry crust. The dressing's job is to hold moisture at the wound while wicking away excess — hence the working shorthand: if it's dry, moisten it; if it's wet, absorb it. Antiseptics deserve the same skepticism you would apply to any drug: full-strength povidone-iodine and hydrogen peroxide are cytotoxic to fibroblasts and have no place being poured routinely into a healing granulating wound.

The nursing work around these agents is as consequential as the agents themselves. Premedicate for pain 30 minutes before a dressing change — burn dressing changes are among the most painful procedures in the hospital, and in the acute phase with massive fluid shifts, analgesia must be given IV, because IM and subcutaneous absorption is unreliable and doses stack up unabsorbed until perfusion returns. Maintain strict aseptic technique, since the burn patient's greatest threat after the first 48 hours is infection. Verify tetanus status on every wound. Support nutrition aggressively — protein and calories are literally the raw material for granulation, and healing fails without them.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Antiresorptive

A drug that slows bone breakdown by suppressing osteoclasts; bisphosphonates, denosumab, raloxifene, and calcitonin. Contrast with anabolic drugs, which build new bone.

Atypical femoral fracture

A transverse fracture of the femoral shaft associated with long-term antiresorptive therapy, typically preceded for weeks by dull thigh or groin pain — a symptom patients must be taught to report.

Bisphosphonate

A drug that binds bone mineral and triggers osteoclast apoptosis when the cell resorbs it; first-line for osteoporosis, and requiring strict upright, empty-stomach, plain-water administration.

Calcitriol

1,25-dihydroxyvitamin D — the fully activated hormone form of vitamin D, produced by the kidney. Given directly when the kidney can no longer perform that step.

Debridement

Removal of nonviable tissue from a wound; may be autolytic, enzymatic, mechanical, sharp/surgical, or biologic.

Disease-modifying antirheumatic drug (DMARD)

A drug that slows the underlying autoimmune joint destruction of rheumatoid arthritis rather than only relieving symptoms; works over weeks to months and is started early.

Elemental calcium

The amount of usable calcium in a supplement, as opposed to the total salt weight — roughly 40% for calcium carbonate and 21% for calcium citrate.

Eschar

Dead, leathery, avascular tissue over a deep burn; because no blood reaches it, systemic antibiotics cannot treat its surface bacteria.

Fingertip unit

The ribbon of topical medication from an adult fingertip to the first crease (about 0.5 g), which covers an area equal to two adult palms — the standard way to teach quantity.

Hypercalcemia

Serum calcium above the normal range, producing "stones, bones, groans, thrones, and psychiatric overtones," constipation, lethargy, and a shortened QT interval.

Osteoblast

The bone-building cell that lays down and mineralizes new matrix, and that also secretes RANKL and osteoprotegerin to regulate osteoclasts.

Osteoclast

The bone-resorbing cell that dissolves mineral and releases calcium into the blood; the target of every antiresorptive drug.

Osteonecrosis of the jaw (ONJ)

Exposed, non-healing jaw bone associated with bisphosphonates and denosumab, most often triggered by dental extraction — hence dental clearance before therapy.

Parathyroid hormone (PTH)

The hormone that raises serum calcium by resorbing bone, increasing renal calcium reabsorption, and activating vitamin D; its analogs, given intermittently, build bone.

Photosensitivity

Exaggerated sunburn response caused by a drug; expected with retinoids, tetracyclines, and several other agents in this chapter, and managed with sunscreen and covering clothing.

RANK ligand (RANKL)

The signal from osteoblasts that drives osteoclast maturation and bone resorption; blocked naturally by osteoprotegerin and pharmacologically by denosumab.

Retinoid

A vitamin A derivative that normalizes epithelial turnover; topical (tretinoin, adapalene) or systemic (isotretinoin, acitretin). All are photosensitizing and the systemic ones are potent teratogens.

Selective estrogen receptor modulator (SERM)

A drug that acts as an estrogen agonist in some tissues and an antagonist in others; raloxifene builds bone and blocks breast tissue while carrying estrogen's clot risk.

Teratogen

A substance that causes fetal malformation. Isotretinoin, acitretin, methotrexate, and leflunomide are among the most dangerous teratogens a nurse will handle.

Tophus

A visible deposit of urate crystals in soft tissue, seen in chronic untreated gout; its presence signals long-standing hyperuricemia needing urate-lowering therapy.

Uricosuric

A drug that lowers serum urate by increasing renal excretion rather than reducing production; probenecid is the prototype, and it requires adequate kidney function and generous fluids.

Xanthine oxidase inhibitor

A drug that blocks the enzyme making uric acid, lowering urate at the source; allopurinol is the prototype and febuxostat the alternative.

Autonomic Drugs

Your patient's heart rate, blood pressure, pupils, bladder, gut, and airways are all being quietly managed — second by second — by a nervous system nobody chose to switch on. Autonomic drugs work by pushing on that system: turning up the gas, stepping on the brake, or cutting a wire. Once you understand which receptor a drug lands on and what that receptor does to the organ underneath it, the adverse effects stop being a list to memorize and start being something you can predict from first principles. This is the chapter that makes the rest of pharmacology click, because so many drugs — for hypertension, asthma, glaucoma, overactive bladder, shock, and anesthesia — are simply autonomic drugs wearing a different name badge.

Section 1The autonomic nervous system

Two divisions, one body

The autonomic nervous system (ANS) runs everything you do not consciously decide: heart rate, vessel tone, breathing passages, digestion, sweating, pupil size, bladder emptying. It has two divisions that mostly oppose each other, and the classic shorthand is worth keeping because it is genuinely predictive. The sympathetic division is fight or flight — the body preparing to run from something. The parasympathetic division is rest and digest — the body settling down to housekeeping. Ask yourself what a person sprinting from danger needs, and sympathetic effects fall out on their own: faster heart, higher pressure, open airways, dilated pupils to see the threat, glucose released for fuel, blood shunted to muscle and away from gut and bladder. Ask what a person napping after a meal needs, and the parasympathetic list appears: slower heart, constricted pupils, active gut, a bladder that empties.

The two divisions differ in their chemistry, and that is where drugs get their leverage. Every autonomic pathway uses two neurons in series with a ganglion (a synapse) between them. At every ganglion, in both divisions, the transmitter is acetylcholine (ACh) acting on nicotinic receptors. What changes is the last step, at the organ itself. Parasympathetic nerves release acetylcholine onto muscarinic receptors — these are the cholinergic synapses. Most sympathetic nerves release norepinephrine onto adrenergic receptors. Two important sympathetic exceptions are worth memorizing now, because they explain odd drug effects later: the adrenal medulla is a modified ganglion that dumps epinephrine straight into the blood as a hormone, and the sweat glands are sympathetic but use acetylcholine on muscarinic receptors — which is exactly why anticholinergic drugs make patients hot and dry.

The receptor map — the single most useful table in pharmacology

Nearly everything in this chapter is an application of the table below. A drug does not have effects because of its name; it has effects because of which receptor it hits and where that receptor lives. Learn the receptor and you have learned the drug, the therapeutic use, and the adverse effect profile in one stroke.

Two memory hooks pay for themselves all semester. “One heart, two lungs” puts beta-1 in the heart and beta-2 in the lungs and never lets you mix them up — and it instantly explains why a nonselective beta blocker is dangerous in asthma. SLUDGE (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis) is the muscarinic picture; the anticholinergic picture is simply its mirror image, which students remember as dry as a bone, red as a beet, blind as a bat, mad as a hatter, hot as a hare.

Four things a drug can do

Every drug in this chapter falls into one of four buckets, and the vocabulary is worth pinning down now. A sympathomimetic (adrenergic agonist) mimics the sympathetic system. A sympatholytic (adrenergic antagonist, or blocker) blocks it. A parasympathomimetic (cholinergic agonist) mimics the parasympathetic system. A parasympatholytic (anticholinergic) blocks it. Notice the elegance hiding in there: blocking one division looks a great deal like stimulating the other. A beta blocker slows the heart, and so does a cholinergic drug — different receptor, same bradycardia on your monitor. Do not let the clinical picture alone tell you which drug your patient took.

Section 2Adrenergic agonists

Turning up the sympathetic gas

An adrenergic agonist, or sympathomimetic, produces the effects the sympathetic nervous system would produce. Some do it directly, by binding the receptor themselves (epinephrine, norepinephrine, phenylephrine, albuterol). Others do it indirectly, by causing the nerve terminal to dump its own stored norepinephrine or by blocking its reuptake (ephedrine, which is mixed direct and indirect; amphetamines; cocaine). Either way the receptor sees more signal, and the organ responds.

What makes this class confusing at first is that a single drug can hit several receptors at once, so its effect depends on which receptors it reaches and at what dose. Selectivity is the whole game. A drug that hits only beta-2 opens airways without racing the heart; one that hits everything opens airways and races the heart and clamps down the vessels. Selectivity is also dose-dependent — push the dose high enough and a “selective” drug starts spilling onto its neighbors. This is precisely why an asthmatic patient who overuses albuterol develops tachycardia and tremor: at high doses the beta-2 selectivity leaks onto beta-1.

Epinephrine: the drug that changes personality with dose

Epinephrine is the prototype and the one to know cold. It is a nonselective agonist — alpha-1, alpha-2, beta-1, and beta-2 — but its receptors have different sensitivities, so the drug behaves differently at different doses. At low doses, beta effects dominate: the heart speeds up, contractility rises, and airways open while skeletal-muscle vessels actually dilate, which can drop the diastolic pressure. At high doses, alpha-1 effects take over and vasoconstriction wins, driving blood pressure up hard. This dose-dependent split is why the same molecule is used for anaphylaxis, for cardiac arrest, for shock, and (in dental and local anesthetic mixtures) to keep lidocaine from washing away.

In anaphylaxis, epinephrine is doing three jobs simultaneously, and the nurse should be able to name all three: alpha-1 constricts vessels to reverse the catastrophic drop in blood pressure and reduce airway edema; beta-1 supports cardiac output; beta-2 dilates the bronchi and stabilizes mast cells against further mediator release. No other drug does all of that. Antihistamines and steroids are adjuncts and never the first move. The first-line route for anaphylaxis is intramuscular into the vault of the lateral thigh (vastus lateralis), because that muscle's rich blood supply absorbs the drug faster and more reliably than subcutaneous tissue or the deltoid. Know the numbers, because this is where the fatal errors happen: the adult dose is 0.3–0.5 mg IM drawn from the 1 mg/mL (1:1,000) concentration, repeated every 5–15 minutes if the response is inadequate; for a child it is 0.01 mg/kg IM, to a maximum of 0.3–0.5 mg. The 0.1 mg/mL (1:10,000) prefilled syringe is the intravenous cardiac-arrest concentration and must never be substituted for the IM anaphylaxis dose — that swap, in either direction, is the classic tenfold concentration error this drug is known for.

The workhorses, drug by drug

Look again at clonidine, because it trips up nearly everyone. It is an agonist, yet it lowers blood pressure. The reason is where its receptor sits: alpha-2 receptors are presynaptic brakes. Stimulating them tells the nerve terminal to release less norepinephrine. So an alpha-2 agonist functionally behaves like a sympathetic blocker — a good reminder that receptor location matters as much as receptor type.

Section 3Adrenergic antagonists

Alpha blockers: releasing the vessels

An alpha-1 blocker stops norepinephrine from constricting vascular smooth muscle. The vessels relax, resistance falls, and blood pressure comes down. The same receptor sits in the bladder neck and prostatic smooth muscle, so blocking it also relaxes the outflow tract — which is why the “-osin” drugs are workhorses in benign prostatic hyperplasia (BPH), letting men empty a bladder that a big prostate had been squeezing shut. Tamsulosin is relatively uroselective and drops pressure less; doxazosin, terazosin, and prazosin lower blood pressure more and are sometimes used for that purpose (prazosin is also used off-label for PTSD-related nightmares, though the trial evidence is mixed).

The signature hazard is first-dose orthostatic hypotension. The first dose — or the first dose after any increase — can drop a patient's pressure sharply enough to cause syncope, and a syncopal fall in an older adult is a hip fracture waiting to happen. The nursing response is concrete: give the first dose at bedtime, teach the patient to rise slowly and to sit on the edge of the bed before standing, warn them not to drive after the first dose, and check orthostatic vitals. Phentolamine is a nonselective alpha blocker used differently — as the antidote for vasopressor extravasation and in the management of catecholamine excess such as pheochromocytoma.

Beta blockers: the “-olol” family

A beta blocker occupies beta receptors so catecholamines cannot. Blocking beta-1 slows the heart rate, weakens contraction, slows AV conduction, and suppresses renin release — the combination that lowers blood pressure, quiets angina by cutting myocardial oxygen demand, controls rate in atrial fibrillation, and, most importantly, improves survival after myocardial infarction and — for three specific agents — in chronic heart failure. That last point deserves emphasis because it is counterintuitive: a drug that weakens contraction helps the failing heart, because it protects it from years of catecholamine flogging. It also deserves emphasis because the benefit does not belong to the class as a whole. Only metoprolol succinate (the extended-release salt), bisoprolol, and carvedilol have proven a mortality benefit in heart failure with reduced ejection fraction; atenolol has no heart failure indication, and plain metoprolol tartrate is not the heart failure agent either. Do not transfer the survival claim to a beta blocker that has not earned it. In heart failure the beta blocker is started at a low dose and titrated up slowly — and never started during an acute decompensation.

The critical distinction in this class is cardioselectivity. Cardioselective agents (metoprolol, atenolol, bisoprolol, esmolol — the ones that start with A through M) block mainly beta-1 and largely spare the lungs. Nonselective agents (propranolol, nadolol, timolol, sotalol — N through Z) block beta-2 as well, which means they can constrict bronchi. That is the mechanism behind the caution in asthma and COPD. The A–M letter trick is a study aid, not a rule — carvedilol and labetalol are the classic exceptions, since both begin in the first half of the alphabet yet block beta-1, beta-2, and alpha-1. Cardioselectivity is also relative, not absolute, and is lost at higher doses, so even a “cardioselective” blocker gets used cautiously in reactive airway disease.

The three cautions a nurse must own

First, never stop a beta blocker abruptly. Chronic blockade upregulates beta receptors, and yanking the drug away exposes a hypersensitized heart to circulating catecholamines — rebound tachycardia, severe hypertension, angina, and infarction have all been documented. Taper over one to two weeks, and teach the patient this explicitly, because a patient who feels fine and stops on their own is the one who ends up in the emergency department.

Second, beta blockers mask hypoglycemia. The trembling, racing heart, and anxiety that warn a diabetic patient their glucose is falling are beta-mediated sympathetic signals — block beta and the warning goes silent. Sweating is the one sign that survives, because sweat glands are cholinergic. Teach patients on beta blockers with diabetes to check their glucose rather than trust how they feel, and never assume a patient without tremor is safe.

Third, hold parameters are yours to enforce. Take an apical pulse for a full minute before every dose. If the heart rate is under 60 or the blood pressure is below the ordered threshold, hold the dose and notify the prescriber — do not simply give it and chart the vitals. Beta blockers also blunt the compensatory tachycardia of hypovolemia, so a bleeding patient on metoprolol may not mount the heart rate you would otherwise expect. In beta blocker overdose — profound bradycardia and hypotension unresponsive to atropine — the specific antidote is glucagon, which raises cardiac cAMP by a route that bypasses the blocked receptor entirely.

Section 4Cholinergic and anticholinergic drugs

Cholinergic agonists: turning up rest-and-digest

A cholinergic agonist (parasympathomimetic) reproduces what acetylcholine does at muscarinic receptors, and the resulting picture is SLUDGE: salivation, lacrimation, urination, defecation, GI cramping, emesis — plus bradycardia, bronchoconstriction, and miosis. Written out that way it sounds purely like a poisoning, and at high doses it is. Used deliberately at therapeutic doses, though, two of those effects are useful. Bethanechol selectively stimulates the bladder detrusor and gut, which makes it the drug for urinary retention that is not caused by an obstruction — a distinction that matters enormously, because squeezing a bladder against a blocked outlet risks rupture. Pilocarpine, given as eye drops, constricts the pupil and opens the drainage angle in glaucoma, and orally it stimulates saliva in xerostomia. Cholinergic agonists are contraindicated in asthma (bronchoconstriction), in bradycardia or heart block, in peptic ulcer disease, and in bowel or bladder obstruction.

AChE inhibitors: making the body's own acetylcholine last longer

Acetylcholinesterase (AChE) is the enzyme that chews up acetylcholine in the synapse within milliseconds. Block the enzyme and acetylcholine lingers, so the same signal hits harder — an indirect cholinergic agonist. This is the mechanism behind three quite different therapies. In myasthenia gravis, where autoantibodies have destroyed nicotinic receptors at the muscle end plate, pyridostigmine keeps acetylcholine around long enough for the surviving receptors to work, restoring strength; the timing of doses around meals matters so patients can chew and swallow safely. In Alzheimer disease, donepezil, rivastigmine, and galantamine raise central acetylcholine — they modestly improve or stabilize symptoms for a time, but they neither cure the disease nor halt the underlying neurodegeneration. And in anesthesia, neostigmine reverses non-depolarizing neuromuscular blockade, which Section 5 takes up.

Push cholinergic stimulation too far and you get cholinergic crisis: profound SLUDGE with bradycardia, bronchoconstriction, copious secretions, and — the part that kills — muscle weakness and respiratory failure from a depolarized, overwhelmed end plate. This is the mechanism of organophosphate poisoning (insecticides and nerve agents), which irreversibly inactivates AChE. The treatment is two drugs, not one: atropine to block the muscarinic effects and dry the secretions, and pralidoxime to pull the organophosphate off the enzyme before the bond “ages” and becomes permanent. Atropine alone will not fix the nicotinic muscle weakness — a fact worth understanding rather than memorizing.

The cruel clinical trap in myasthenia is that myasthenic crisis (too little drug) and cholinergic crisis (too much) both present as severe weakness and respiratory failure. The differentiator is the company the weakness keeps: cholinergic crisis brings SLUDGE — drooling, tearing, cramping, tiny pupils, bradycardia — while myasthenic crisis does not. Either way the airway comes first.

Anticholinergics: blocking rest-and-digest

An anticholinergic (antimuscarinic, parasympatholytic) blocks muscarinic receptors, so the picture is SLUDGE in reverse: dry mouth, no sweat, blurred near vision and dilated pupils, tachycardia, constipation, and urinary retention, with confusion when the drug reaches the brain. Atropine is the prototype — the drug you push for symptomatic bradycardia, use to dry secretions preoperatively, and reach for in organophosphate poisoning. Ipratropium and tiotropium are inhaled anticholinergics that bronchodilate in COPD by a route completely different from albuterol's, which is why the two are often combined. Oxybutynin, tolterodine, and solifenacin quiet an overactive bladder. Scopolamine patches prevent motion sickness. Benztropine and trihexyphenidyl rebalance the dopamine–acetylcholine seesaw in Parkinson disease and in drug-induced extrapyramidal symptoms.

Every one of those anticholinergic effects is predictable from the table in Section 1, and so is the danger. Anticholinergic burden is the additive load of every drug with antimuscarinic activity a patient is taking — and it is not just the drugs above. Many antihistamines, tricyclic antidepressants, and antipsychotics carry hidden antimuscarinic activity. Stack three or four in an 80-year-old and you get confusion, falls, retention, and constipation that get misread as “dementia” or “just getting older.” Counting up anticholinergic burden on a medication list is one of the highest-yield things a nurse can do for an older patient.

Section 5Neuromuscular blockers

A different synapse, a much higher stake

Neuromuscular blocking agents (NMBAs) are technically somatic, not autonomic, but they belong here because they work on the same molecule — acetylcholine — at a nicotinic receptor. They act at the neuromuscular junction, on the N_M receptor of the skeletal muscle end plate, to produce flaccid paralysis for intubation, surgery, and mechanical ventilation.

Three facts must be absolutely fixed before any of the pharmacology matters. These drugs do not sedate. They do not relieve pain. They do not cause amnesia. A paralyzed patient who has not been given adequate sedation and analgesia is fully awake, feeling everything, and unable to move a finger or make a sound to tell you — among the most terrifying experiences medicine can inflict. NMBAs are high-alert medications, stored separately with auxiliary warnings, and they are never given except where the airway can be secured and mechanical ventilation is immediately available. Paralysis always includes the diaphragm. The nurse's obligations are non-negotiable: confirm deep sedation and analgesia are running first, never allow paralysis without a secured airway, provide eye lubrication and taping (the blink is gone), reposition to prevent pressure injury, provide DVT prophylaxis, and keep talking to the patient because hearing is unaffected.

Depolarizing blockade: succinylcholine

Succinylcholine is the only depolarizing agent in common use, and it works by an odd trick: it is an agonist that paralyzes. It binds the nicotinic receptor and opens it — producing an initial wave of disorganized contractions called fasciculations — but unlike acetylcholine it is not broken down by acetylcholinesterase, so it sits on the receptor and holds the end plate depolarized. A depolarized membrane cannot fire again, and the muscle goes flaccid. Onset is under a minute and the effect wears off in five to ten minutes as plasma pseudocholinesterase metabolizes it, which is exactly the profile you want for rapid sequence intubation.

Three hazards define it. First, there is no reversal agent — you wait it out, ventilating the patient the whole time. Giving an AChE inhibitor would only prolong the block by adding more acetylcholine to an already depolarized plate. Second, the depolarization leaks potassium out of every muscle cell in the body, so succinylcholine is contraindicated in patients with existing hyperkalemia, and in burns, crush injury, denervation, spinal cord injury, or prolonged immobility beyond roughly 24–48 hours, where receptor upregulation can produce a potassium surge large enough to cause cardiac arrest. The same mechanism drives the drug's boxed warning: a child or adolescent with an undiagnosed skeletal muscle myopathy — Duchenne muscular dystrophy above all, often not yet apparent in a young boy — can develop hyperkalemic rhabdomyolysis, ventricular dysrhythmia, and cardiac arrest after a single dose. For that reason succinylcholine is not used for routine or elective intubation in children and adolescents; its pediatric use is reserved for emergency airway control. Third, succinylcholine is a leading trigger of malignant hyperthermia in genetically susceptible patients — a hypermetabolic crisis whose earliest reliable sign is a rising end-tidal CO₂, with masseter rigidity, tachycardia, and a late temperature spike. The antidote is dantrolene, which must be immediately available wherever the drug is used. A rare patient with atypical pseudocholinesterase stays paralyzed for hours; the management is simply continued ventilation and sedation until it clears.

Non-depolarizing blockade: the “-curium” and “-curonium” drugs

Rocuronium, vecuronium, cisatracurium, and atracurium take the more intuitive route: they are competitive antagonists that occupy the nicotinic receptor without activating it, so acetylcholine cannot get in. There are no fasciculations, onset is slower (though a large dose of rocuronium approaches succinylcholine's speed), and the block lasts much longer. Because the blockade is competitive, it is reversible — flood the junction with enough acetylcholine and it outcompetes the drug. That is what neostigmine does, and it is always given with glycopyrrolate or atropine, because the extra acetylcholine spilling onto muscarinic receptors would otherwise cause bradycardia and drowning secretions. Sugammadex is the newer and cleaner option: it physically encapsulates rocuronium or vecuronium molecules and drags them out of circulation, reversing even deep blockade in minutes without touching the cholinergic system at all. Cisatracurium earns a special mention because it degrades spontaneously in plasma (Hofmann elimination) rather than through liver or kidney, making it the agent of choice in organ failure.

Monitoring is where the nurse lives with these drugs. Train-of-four (TOF) peripheral nerve stimulation delivers four small shocks and counts the resulting twitches; the depth of blockade is titrated to a target, commonly one to two twitches out of four for a continuous infusion. Fewer twitches means deeper block and a longer, harder recovery. Before extubation, recovery is judged by objective criteria — sustained head lift, adequate tidal volume and grip, the ability to protect the airway — and never by appearance alone, because a patient can look awake while still too weak to breathe. Remember too that several common drugs deepen and prolong blockade: aminoglycoside antibiotics, magnesium sulfate, calcium channel blockers, inhaled anesthetics, hypothermia, and acidosis. A postpartum patient on a magnesium drip is a different pharmacologic problem than the same patient without it.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Acetylcholine (ACh)

The transmitter at all autonomic ganglia, at parasympathetic organ synapses, at sympathetic sweat glands, and at the skeletal muscle end plate.

Acetylcholinesterase (AChE)

The enzyme that breaks down acetylcholine in the synapse; blocking it amplifies and prolongs cholinergic signaling.

Alpha-1 receptor

Receptor on vascular smooth muscle, pupil, and bladder neck; stimulation causes vasoconstriction, mydriasis, and urinary retention.

Alpha-2 receptor

Presynaptic and central receptor whose stimulation reduces norepinephrine release, lowering blood pressure (clonidine).

Anticholinergic (antimuscarinic)

A drug that blocks muscarinic receptors, producing dry mouth, blurred vision, tachycardia, constipation, retention, and confusion.

Anticholinergic burden

The cumulative antimuscarinic load from all of a patient's drugs, a major cause of confusion and falls in older adults.

Autonomic nervous system

The involuntary nervous system controlling heart, vessels, airways, gut, bladder, glands, and pupils.

Beta-1 receptor

Cardiac (“one heart”) and renal receptor; stimulation raises rate, contractility, conduction, and renin release.

Beta-2 receptor

Pulmonary (“two lungs”), vascular, uterine, and hepatic receptor; stimulation causes bronchodilation and vasodilation.

Cardioselective

Describing a beta blocker that acts mainly on beta-1 and largely spares beta-2; selectivity is relative and lost at high doses.

Cholinergic crisis

Excess cholinergic stimulation causing SLUDGE plus muscle weakness and respiratory failure; the mirror trap of myasthenic crisis.

Depolarizing blocker

A neuromuscular blocker (succinylcholine) that activates and then holds the end plate depolarized; has no reversal agent.

Extravasation

Leakage of a vesicant such as a vasopressor into surrounding tissue, risking necrosis; reversed locally with phentolamine.

Malignant hyperthermia

A hypermetabolic crisis triggered by succinylcholine or volatile anesthetics; earliest sign is rising end-tidal CO₂; antidote is dantrolene.

Muscarinic receptor

The acetylcholine receptor on parasympathetic target organs; stimulation produces the SLUDGE picture.

Neuromuscular blocking agent (NMBA)

A high-alert drug that paralyzes skeletal muscle at the nicotinic end plate without sedating or relieving pain.

Nicotinic receptor

The acetylcholine receptor at autonomic ganglia (N_N) and at the skeletal muscle end plate (N_M).

Non-depolarizing blocker

A competitive nicotinic antagonist (rocuronium, vecuronium, cisatracurium) reversible with neostigmine or sugammadex.

Parasympathetic division

The rest-and-digest division; acetylcholine on muscarinic receptors slows the heart and activates gut and bladder.

SLUDGE

Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis — the muscarinic (cholinergic excess) picture.

Sympathetic division

The fight-or-flight division; mostly norepinephrine on adrenergic receptors, plus adrenal epinephrine release.

Train-of-four (TOF)

Peripheral nerve stimulation delivering four impulses to gauge the depth of neuromuscular blockade by counting twitches.

Endocrine Drugs

The endocrine system runs on chemical messages sent slowly, in tiny amounts, through the bloodstream — and endocrine pharmacology is mostly the art of replacing a message the body has stopped sending, or muffling one it is sending too loudly. That sounds simple until you meet the feedback loop, which quietly turns off the patient's own gland the moment you supply the hormone from outside. Almost every endocrine drug error a nurse will ever see traces back to that one fact, or to a decimal point in an insulin dose. This chapter walks through the pituitary, the thyroid, the adrenal cortex, and the pancreas — the four glands you will medicate most — and the safety habits that keep those drugs from hurting the person you gave them to.

Section 1Hormone principles and the pituitary

What makes a hormone drug different

A hormone is a chemical messenger released by a gland into the blood, carried to a distant tissue, and recognized there by a receptor built to fit it. Two features of that arrangement matter enormously at the bedside. First, hormones work at vanishingly small concentrations — a therapeutic dose of levothyroxine is measured in micrograms, a thousandth of the milligram doses you are used to — so a misplaced decimal point is a tenfold error, and confusing micrograms with milligrams is a thousandfold one. Second, hormones come in two chemical families that behave completely differently as drugs.

Lipid-soluble hormones (thyroid hormone and the steroid hormones such as cortisol) slip straight through the cell membrane and act on receptors inside the cell, changing which genes get transcribed. Because they work by building new proteins, their effects come on over hours to days and linger after the drug is gone — and because they are fat-soluble, they survive the gut and can be given by mouth. Water-soluble hormones (insulin, growth hormone, glucagon, vasopressin, and the other peptides) cannot cross the membrane; they dock on a receptor on the cell surface and trigger a fast intracellular signaling cascade. They act in minutes — and they are proteins, which means digestive enzymes destroy them. That single chemical fact is why insulin cannot be a pill. It is not a marketing decision or a gap in the science; a swallowed peptide is simply lunch.

Negative feedback: the idea the whole chapter rests on

Endocrine glands are governed by negative feedback, a thermostat arrangement. The hypothalamus signals the anterior pituitary, the pituitary signals the target gland, the target gland releases its hormone — and that circulating hormone travels back and switches off the hypothalamus and pituitary that ordered it. The classic example is the thyroid axis: TRH → TSH → thyroid hormone → suppression of TRH and TSH. The adrenal axis works the same way: CRH → ACTH → cortisol → suppression of CRH and ACTH.

Here is the clinical consequence, and it is worth reading twice. The loop cannot tell the difference between hormone made by the patient and hormone you injected. When you give prednisone daily for two months, the patient's hypothalamus sees plenty of steroid, stops sending CRH, the pituitary stops sending ACTH, and the adrenal cortex — unused, unstimulated — atrophies. Stop the prednisone abruptly and there is no cortisol from either source: the drug is gone and the gland cannot answer. That is adrenal crisis, and it is the reason you will hear "never stop a steroid suddenly" for the rest of your career. The same logic explains why replacement doses are titrated against the pituitary's signal — a TSH level is really the pituitary's opinion of whether your levothyroxine dose is right.

Drugs that act at the pituitary

The pituitary is two glands in one coat. The anterior pituitary manufactures its own hormones — growth hormone, TSH, ACTH, prolactin, FSH, LH. The posterior pituitary manufactures nothing; it is a storage tank for two hormones made in the hypothalamus, antidiuretic hormone (ADH, vasopressin) and oxytocin. Pituitary drugs either replace a missing signal or shut down an excessive one.

Notice the pattern hiding in that table: diabetes insipidus and SIADH are mirror images, and so are their drugs. In diabetes insipidus there is too little ADH, so the kidney cannot hold water — the patient pours out liters of pale, dilute urine, the specific gravity is low, and the serum sodium climbs. You give desmopressin. In SIADH there is too much ADH, water is retained, urine is scant and concentrated, and the sodium falls. Give too much desmopressin and you have simply converted the first problem into the second — which is why the monitoring for desmopressin is not the urine output alone but the sodium.

Section 2Thyroid drugs

Levothyroxine: replacing what is missing

Thyroid hormone sets the body's metabolic idle speed. Too little and everything slows — the patient is cold, constipated, bradycardic, gaining weight, thinking through fog. Levothyroxine (T4) is the synthetic replacement, and it is one of the most-prescribed drugs in the country. It is chemically identical to the T4 the thyroid makes, and the body converts it to the more active T3 at the tissues, which is exactly why T4 is preferred over giving T3 directly: the patient's own tissues decide how much active hormone they need. Levothyroxine has a long half-life (about 7 days), so it is a once-daily drug, effects take weeks to appear, and a single missed dose is not an emergency.

It is also a narrow therapeutic index drug, which drives everything about how it is taken. Give it on an empty stomach with water, 30–60 minutes before breakfast, at the same time every day. Food — especially soy, walnuts, high-fiber meals, and coffee — blunts absorption. Calcium, iron, multivitamins, antacids, sucralfate, and cholestyramine bind it in the gut; separate those by at least 4 hours. Because absorption is so finicky, patients should stay on the same product and not switch brands casually. Dose is titrated against the TSH, rechecked about 6–8 weeks after any change — sooner is just measuring noise, because the hormone has not reached steady state.

Teach the patient what over-replacement feels like, because it looks exactly like hyperthyroidism: tachycardia, palpitations, nervousness, insomnia, heat intolerance, tremor, unintended weight loss. In older adults, an excessive dose brings two real hazards — atrial fibrillation and, over years, osteoporosis. This is why an older patient, or anyone with coronary artery disease, is started on a deliberately low dose and increased slowly: a suddenly faster heart in an already-narrowed coronary artery can precipitate angina or infarction. Two more teaching points that come up constantly: levothyroxine is lifelong — feeling better is evidence it is working, not permission to stop — and requirements increase during pregnancy, so a pregnant patient needs her dose and her TSH revisited early.

Antithyroid agents: turning the gland down

Hyperthyroidism is the opposite picture — racing heart, weight loss despite eating, heat intolerance, tremor, anxiety, diarrhea. The thionamides, methimazole and propylthiouracil (PTU), block the enzyme that builds thyroid hormone. They do not touch hormone already stored in the gland, so the patient does not improve for several weeks — a fact worth telling them up front, or they will decide the drug does not work and quit.

Methimazole is first-line: it is more potent, dosed once daily, and better tolerated. PTU is reserved for three situations — the first trimester of pregnancy (methimazole carries a teratogenic risk in early pregnancy), thyroid storm (PTU has the extra benefit of blocking peripheral T4-to-T3 conversion), and patients who cannot take methimazole — because PTU carries a boxed warning for severe hepatotoxicity, including liver failure. Both drugs share the effect you must burn into memory: agranulocytosis. If a patient on a thionamide reports a sore throat, fever, or mouth ulcers, that is not a cold. Hold the drug, notify the provider, and get a CBC with differential.

Section 3Corticosteroids

Two jobs in one gland

The adrenal cortex makes two kinds of steroid that matter here. Glucocorticoids — cortisol is the natural one — raise blood glucose, suppress inflammation, dampen the immune system, and help the body survive stress. Mineralocorticoids — aldosterone is the natural one — make the kidney retain sodium and water and excrete potassium. Every corticosteroid drug you give is a blend of those two activities, and the blend is the whole reason there are so many of them.

Hydrocortisone is essentially cortisol, with both activities, which makes it the drug of choice when you are replacing a missing adrenal gland. Prednisone and methylprednisolone are mostly glucocorticoid with a little mineralocorticoid — the everyday anti-inflammatories. Dexamethasone is nearly pure glucocorticoid, very potent, long-acting, and carries almost no salt-retaining effect, which is why it is chosen for cerebral edema and for situations where fluid retention would be a problem. Fludrocortisone is the mirror image: chosen for its mineralocorticoid punch, to replace aldosterone. One more thing about prednisone worth knowing: it is a prodrug, activated by the liver into prednisolone, so a patient in liver failure may be given prednisolone directly.

The adverse effects: predictable, and all one story

Every classic steroid side effect is just cortisol's normal job, turned up too far and left on too long. Cortisol raises glucose → steroids cause hyperglycemia, and a diabetic patient started on prednisone will need more insulin, not less. Cortisol suppresses immunity → steroids bring infection risk, and worse, they mask the signs: they blunt fever and inflammation, so a serious infection can be well advanced before it announces itself. Cortisol is catabolic → long-term use brings muscle wasting, thin fragile skin, easy bruising, poor wound healing, and osteoporosis. Redistributed fat gives the cushingoid look: moon face, buffalo hump, truncal obesity on thin limbs. Add mood changes (euphoria, agitation, insomnia, occasionally frank psychosis), GI irritation and ulcer risk (worse with concurrent NSAIDs), cataracts and glaucoma, growth suppression in children, and — from the mineralocorticoid side — fluid retention, hypertension, and hypokalemia.

The nursing translation is short and concrete: check blood glucose even in patients who are not diabetic, take daily weights and blood pressures, monitor potassium, give oral doses with food, watch for any infection with a low index of suspicion, and teach the patient to avoid crowds and sick contacts and to report any fever. Live vaccines are generally avoided in patients on immunosuppressive doses. Doses are usually given in the morning, mimicking the body's natural cortisol peak — which both reduces insomnia and disturbs the axis a little less. And every patient on chronic steroids should carry medical identification.

Tapering, and the crisis that follows if you don't

Return to the feedback loop from Section 1. After roughly two to three weeks of systemic steroid at a meaningful dose, the HPA axis is suppressed and the adrenal cortex begins to atrophy. It cannot resume production on demand. So a course of more than about two weeks is tapered — the dose stepped down gradually over days to weeks — giving the hypothalamus, pituitary, and adrenal time to wake up in sequence. Stop abruptly and the patient falls into acute adrenal insufficiency (adrenal crisis): hypotension, shock, weakness, nausea and vomiting, abdominal pain, hypoglycemia, and dilutional hyponatremia. Notice what is not on that list: the potassium is usually normal. The steroid suppressed ACTH only, and aldosterone answers to renin and angiotensin rather than to ACTH, so it keeps working. Hyperkalemia belongs to primary adrenal insufficiency (Addison's disease), where the cortex itself fails and aldosterone is lost too — which is why those patients also need fludrocortisone. Either way it is a genuine emergency treated with IV hydrocortisone and fluids.

The same physiology explains stress dosing. A healthy adrenal gland pumps out extra cortisol during surgery, trauma, or serious infection; a suppressed one cannot. So patients on chronic steroids need increased doses during physiologic stress — and this is exactly when a well-meaning patient with a stomach flu decides to skip their pills because they feel too sick to eat. Teach the reverse: sick days are when the dose matters most, and if they cannot keep it down, they need to be seen.

Section 4Insulins

The highest of the high-alert drugs

Insulin is the hormone that lets glucose out of the blood and into cells, and it is the drug that appears on every "high-alert" list in every hospital in the country — not because it is unpredictable, but because the consequences of a wrong dose are immediate and can be fatal. The safety practices are non-negotiable and worth stating plainly. Use an insulin syringe (U-100) or an insulin pen — never a tuberculin or general-purpose syringe. Never write or accept the abbreviation "U" for units; a hand-written "10U" reads as "100" often enough that the abbreviation is banned outright. Most facilities require an independent double-check by a second nurse before administration. And because insulin names look and sound alike — glargine, glulisine, lispro, degludec, detemir — read the vial label, not the shelf position.

Insulin is given subcutaneously for routine use; the abdomen absorbs fastest and most predictably, then the arm, thigh, and buttock. Rotate within one anatomic area rather than hopping between areas, so absorption stays consistent, and space injections about an inch apart to prevent lipohypertrophy — the rubbery fatty lumps that form in an overused site and absorb insulin erratically. Do not massage the site, and do not exercise the injected limb right away; both speed absorption and can drop the glucose faster than expected. Unopened vials live in the refrigerator; the in-use vial or pen can stay at room temperature and is generally discarded after 28 days (check the specific product). Never give cold insulin from the fridge if you can help it — it stings.

Onset, peak, duration: the numbers that prevent hypoglycemia

Insulins are not all the same molecule. Regular and NPH are human insulin — NPH being that same insulin complexed with protamine so it dissolves out of the tissue slowly. The rapid- and long-acting products are analogs: amino-acid substitutions (lispro, aspart, glulisine, glargine) or added fatty-acid side chains (detemir, degludec) that change how the molecules clump together, precipitate, and seep into the blood. That structural difference is the whole story — it is why glargine, which precipitates at tissue pH, can never be mixed with anything, and why protamine carried into a regular insulin vial would blunt your fast insulin. The peak is the number that matters clinically, because the peak is when the patient will go low. Learn the peaks and you can predict hypoglycemia instead of discovering it.

When two insulins are drawn into one syringe — classically NPH plus regular — the sequence is fixed: inject air into the cloudy (NPH) vial, inject air into the clear (regular) vial, withdraw the clear first, then the cloudy. Clear before cloudy — or, as generations of students have said it, regular before NPH. The reason is contamination: a trace of clear regular insulin carried into the NPH vial is harmless, but a trace of NPH's protamine carried into the regular vial would slow the action of your fast insulin, and you would never know it happened.

Hypoglycemia

A blood glucose below 70 mg/dL is hypoglycemia and it is the acute danger of every insulin. The early signs are adrenergic — the body's alarm system firing: shaky, sweaty, tachycardic, anxious, hungry, pale. If it drops further, the brain runs out of fuel and the signs turn neuroglycopenic: confusion, slurred speech, blurred vision, odd behavior, seizure, coma. That second set is often mistaken for intoxication or a stroke, and an unresponsive diabetic patient gets a fingerstick before anything else. Note that a patient on a beta blocker may lose the adrenergic warning entirely — the tremor and tachycardia are blocked — and will present with confusion as the first sign. Diaphoresis usually still comes through.

Treatment is the rule of 15: if the patient is awake and can swallow, give 15 grams of fast-acting carbohydrate — 4 ounces of juice or regular soda, 3–4 glucose tablets, a tablespoon of honey — wait 15 minutes, and recheck. Repeat until above 70, then give a snack with protein and a complex carbohydrate if the next meal is more than an hour away, so the glucose does not simply fall again. If the patient cannot safely swallow, nothing goes in the mouth: give IV dextrose 50% if there is access, or glucagon (IM, SC, or intranasal) if there is not.

Section 5Oral antidiabetics and glucagon

Metformin: the one to know cold

Type 2 diabetes is a problem of resistance — there is insulin, but the tissues have stopped listening, and the liver keeps pouring out glucose it does not need to. Metformin, a biguanide, is first-line therapy for almost every newly diagnosed adult, and it is worth knowing better than any other oral agent. It works in three ways: it decreases hepatic glucose production (its main effect), it decreases intestinal glucose absorption, and it increases the sensitivity of muscle and fat to the insulin already present.

Read that list again and notice what is absent: metformin does not squeeze more insulin out of the pancreas. That is why metformin alone does not cause hypoglycemia — a point tested relentlessly and, more importantly, a point that changes how you teach. It is also weight-neutral to modestly weight-reducing, which is a genuine advantage. Its everyday problem is the gut: nausea, diarrhea, cramping, metallic taste, largely solved by taking it with food, starting low, and using the extended-release form. Long-term use can cause vitamin B₁₂ deficiency, so B₁₂ is checked periodically — particularly if a patient develops anemia or neuropathy.

The rare but serious effect is lactic acidosis, which carries a boxed warning. It happens when metformin accumulates, so the risk sits with anything that impairs clearance or oxygenation: renal impairment (metformin is contraindicated at eGFR <30), acute heart failure, hypoxia, sepsis, dehydration, liver disease, and heavy alcohol use. Teach the signs, because they are vague and easy to dismiss: unusual muscle aches, deep or labored breathing, unusual sleepiness, abdominal pain, feeling generally unwell. It is also the reason iodinated contrast keeps coming up on this drug: contrast can injure the kidney, and the kidney is metformin's only exit route. The current rule is narrower than the blanket hold you may still hear on the unit. Metformin is continued through intravenous contrast when the eGFR is 30 mL/min/1.73 m² or better and there is no acute kidney injury. It is withheld at the time of the study and for 48 hours afterward, pending a repeat creatinine and eGFR, only when the eGFR is under 30, when AKI is present or suspected, or when the contrast is given intra-arterially in a way likely to expose the renal arteries.

The other classes, and the one alert that defines each

A few threads run through that table. The agents that push the pancreas — sulfonylureas and meglitinides — are the oral drugs that cause hypoglycemia; the rest are much safer alone, though any of them can contribute when combined with insulin. Two classes now get prescribed as much for the heart and kidney as for the sugar: SGLT2 inhibitors and GLP-1 agonists both showed cardiovascular and renal benefit in outcome trials, which is why you will find them on the medication list of patients whose A1C is nearly at goal. And the euglycemic DKA of the SGLT2 drugs deserves a moment: because the drug dumps glucose into the urine, a patient can be in genuine ketoacidosis — nauseated, breathing deeply, acidotic — with a glucose of 180. A normal fingerstick does not rule it out.

Glucagon: the rescue

Glucagon is insulin's opposite number, the other hormone of the islets. When glucose falls, alpha cells release it, and it tells the liver to break down stored glycogen into glucose and release it into the blood. As a drug it is the rescue for severe hypoglycemia in a patient who cannot safely swallow and has no IV access — a seizing patient, an unresponsive patient, a child at home. It is given IM, subcutaneously, or intranasally, and it works in roughly 10–15 minutes.

Three things about glucagon must be taught to the family, not just charted. First, it works by emptying the liver's glycogen stores — so it fails or works poorly in a patient with no stores: chronic alcohol use, starvation, prolonged fasting, advanced liver disease. Those patients need IV dextrose. Second, vomiting is common after glucagon, so turn the patient onto their side before it takes effect to protect the airway. Third, the effect is temporary — the liver's stores are finite and the insulin that caused the low is often still working. As soon as the patient is awake and can swallow, they need oral carbohydrate, and they still need to be evaluated. Rescuing someone with glucagon and leaving is how a patient goes low a second time an hour later.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Adrenal crisis

Acute, life-threatening cortisol deficiency — hypotension, shock, weakness, vomiting, hypoglycemia, dilutional hyponatremia — classically triggered by abruptly stopping a chronic steroid or by physiologic stress in a patient with a suppressed axis. Potassium is usually normal in this steroid-withdrawal (secondary) form because aldosterone is preserved; hyperkalemia points to primary (Addison's) disease. Treated with IV hydrocortisone and fluids.

Agranulocytosis

A dangerous fall in neutrophils, leaving the patient defenseless against infection; the reason a sore throat, fever, or mouth ulcer on methimazole or PTU is an emergency, not a cold.

Antidiuretic hormone (ADH, vasopressin)

The posterior pituitary hormone that makes the kidney conserve water. Too little causes diabetes insipidus; too much causes SIADH.

Basal insulin

Long-acting, peakless insulin (glargine, detemir, degludec) that covers the body's constant background need between meals and overnight.

Biguanide

The class containing metformin; lowers hepatic glucose production and improves insulin sensitivity without stimulating the pancreas.

Duration

How long an insulin continues to lower glucose after it is given.

Euglycemic DKA

Diabetic ketoacidosis occurring with a near-normal blood glucose, seen with SGLT2 inhibitors because the drug excretes glucose in the urine; a normal fingerstick does not rule it out.

Glucagon

The pancreatic alpha-cell hormone that mobilizes hepatic glycogen to raise blood glucose; used as rescue for severe hypoglycemia when the patient cannot swallow.

Glucocorticoid

A steroid whose main actions are raising blood glucose and suppressing inflammation and immunity; cortisol is the natural one, prednisone and dexamethasone the common drugs.

High-alert medication

A drug that carries a heightened risk of significant patient harm when used in error — insulin is the archetype — and therefore requires extra safeguards such as an independent double-check.

Hypoglycemia

Blood glucose below 70 mg/dL; early adrenergic signs (shaky, sweaty, tachycardic, hungry) give way to neuroglycopenic ones (confusion, slurred speech, seizure, coma).

Incretin

A gut hormone (chiefly GLP-1) released with a meal that stimulates insulin, suppresses glucagon, and slows gastric emptying; mimicked by GLP-1 agonists and prolonged by DPP-4 inhibitors.

Lactic acidosis

The rare, serious metformin toxicity that occurs when the drug accumulates; suspect it with muscle aches, deep or labored breathing, unusual sleepiness, and abdominal pain.

Lipohypertrophy

Rubbery fatty thickening at an overused injection site that absorbs insulin unpredictably; prevented by rotating within an anatomic area.

Mineralocorticoid

A steroid whose main action is sodium and water retention with potassium loss; aldosterone is the natural one, fludrocortisone the drug.

Narrow therapeutic index

A drug whose effective dose and toxic dose sit uncomfortably close together, demanding precise dosing and monitoring — levothyroxine and insulin both qualify.

Negative feedback

The thermostat arrangement in which a hormone shuts off the signals that ordered it; the loop cannot tell exogenous hormone from the patient's own.

Onset

How long after administration an insulin begins to lower blood glucose.

Peak

When an insulin exerts its maximum effect — and therefore when hypoglycemia is most likely.

Rule of 15

Treatment of hypoglycemia in a patient who can swallow: 15 grams of fast-acting carbohydrate, wait 15 minutes, recheck, repeat as needed.

Taper

The gradual stepwise dose reduction used to end corticosteroid therapy, allowing the suppressed HPA axis and atrophied adrenal cortex to resume production.

Thionamide

The antithyroid class — methimazole and propylthiouracil — that blocks thyroid hormone synthesis; effects take weeks because stored hormone is unaffected.

Cardiovascular Drugs I

Blood has one job that is nearly impossible: stay liquid everywhere, and turn solid in exactly one place, at exactly the right moment. The drugs in this chapter live on both sides of that line — some thin the blood, some help it clot, some rebuild it, and some quietly lower the pressure that is grinding down a patient's arteries year after year. Almost every one of them is a high-alert medication, meaning an error does not produce a rash, it produces a hemorrhage or a stroke. This chapter walks the clotting cascade, the anticoagulants and antiplatelets that interrupt it, the antidotes that reverse them, the agents that rebuild blood, and the antihypertensives you will hang, titrate, hold, and teach more than any other class in your career.

Section 1Hemostasis and anticoagulants

How the body builds a clot

Cut a vessel and three things happen in sequence. First, the vessel wall clamps down — vasoconstriction — narrowing the hole. Second, platelets stick to the exposed collagen, activate, change shape, and glue themselves to one another into a soft, temporary platelet plug. That plug will stop a paper cut, but it is fragile; a cough or a blood pressure spike blows it off. So third, the body reinforces it with the coagulation cascade, a chain of plasma proteins that ends by weaving a mesh of fibrin through the platelet plug and locking it in place.

The cascade has two on-ramps and one shared exit. The extrinsic pathway is the fast one: damaged tissue releases tissue factor, which activates factor VII. The intrinsic pathway is the slower one, triggered by contact with a damaged surface inside the vessel. Both funnel into the common pathway, where factor X becomes factor Xa, Xa converts prothrombin (factor II) into thrombin, and thrombin converts fibrinogen into fibrin. Thrombin is the engine of the whole system, and factor Xa is the gate just upstream of it — which is exactly why so many drugs aim at those two proteins.

Two lab tests map onto those two on-ramps, and you will read them for the rest of your career. PT/INR follows the extrinsic and common pathways — it is the warfarin test. aPTT follows the intrinsic and common pathways — it is the heparin test. A memory hook that works: PeT the extrinsic dog (PT → extrinsic → warfarin); the PTT is for the intrinsic tubing (aPTT → intrinsic → heparin).

One more idea before the drugs: nothing here dissolves a clot that already exists. Anticoagulants prevent clots from forming and from growing. They do not melt the clot in the patient's leg — the body's own fibrinolytic system does that slowly over weeks. When a patient asks, "Is this shot breaking up my clot?", the honest answer is that it is holding the line while the body cleans up.

Heparins — fast, injectable, reversible

Unfractionated heparin (UFH) works indirectly: it binds antithrombin and makes it roughly a thousand times better at inactivating thrombin and factor Xa. Because it does not touch the liver's factor production, it works within minutes — IV heparin is essentially instant, which is why it is the drug of choice when you need anticoagulation now and might need to shut it off just as fast. Its half-life is short (about 60–90 minutes), so stopping the drip is itself a partial reversal. Monitor with aPTT (goal typically 1.5–2.5 times control) or an anti-Xa level, per your facility's protocol and nomogram. The antidote is protamine sulfate.

The complication that defines heparin is heparin-induced thrombocytopenia (HIT). It is counterintuitive and it kills people: an antibody response, typically 5–10 days in, drops the platelet count by 50% or more and paradoxically causes clotting, not bleeding. A falling platelet count on heparin is never something to watch overnight. Heparin is stopped — all of it, including flushes and coated catheters — and a non-heparin anticoagulant such as argatroban is started. Baseline and serial platelet counts are a nursing responsibility, not a lab formality.

Low–molecular-weight heparin (LMWH) — prototype enoxaparin (Lovenox) — is heparin chopped into shorter chains that inhibit factor Xa much more than thrombin. That gives a predictable, weight-based subcutaneous dose, no routine aPTT, a longer half-life, and a lower HIT risk, which is what let anticoagulation move out of the hospital. Give it deep subcutaneously in the abdominal "love handle," at least 2 inches from the umbilicus, and do not expel the air bubble in the prefilled syringe — that bubble clears the drug from the needle track and reduces bruising. Do not aspirate and do not massage the site. LMWH is cleared renally, so it accumulates dangerously in kidney impairment; it also carries a boxed warning about spinal/epidural hematoma with neuraxial anesthesia or spinal puncture — a warning shared by fondaparinux and the DOACs, so timing around an epidural is always a team decision. Fondaparinux is a synthetic indirect factor Xa inhibitor given subcutaneously — like heparin it works through antithrombin, which is why it is not a DOAC and why protamine does not reverse it. It has essentially no reliable reversal agent, which is a real consideration when choosing it.

Warfarin — slow, oral, and endlessly interactive

Warfarin (Coumadin) blocks vitamin K epoxide reductase, the enzyme that recycles vitamin K in the liver. Without recycled vitamin K, the liver cannot finish building the vitamin K–dependent factors — II, VII, IX, and X (the "1972" factors), plus the natural anticoagulants protein C and protein S. Notice what that means: warfarin does nothing to the factors already circulating. It takes 3–5 days for the existing factors to decay before the patient is truly anticoagulated, which is why a patient with an acute clot is bridged with heparin or LMWH until the INR is therapeutic on two consecutive days.

Monitor with PT/INR. The usual goal is an INR of 2.0–3.0; a mechanical mitral valve or certain higher-risk indications may target 2.5–3.5. The antidote is vitamin K (phytonadione), and for serious or life-threatening bleeding, 4-factor prothrombin complex concentrate (PCC), which replaces the missing factors in minutes rather than hours. Fresh frozen plasma is an older alternative when PCC is unavailable.

Route matters, and it is a nursing decision point. A high INR without bleeding is managed by holding doses and, if vitamin K is ordered at all, giving it orally (typically 2.5–5 mg). Major bleeding gets phytonadione 5–10 mg IV together with 4-factor PCC — vitamin K restarts the liver's factor production over hours, PCC replaces the factors now, and giving PCC without vitamin K lets the INR rebound as the concentrate wears off. The IV and IM routes carry a boxed warning: severe, occasionally fatal hypersensitivity/anaphylactoid reactions have occurred, including with the first dose. So the IV dose is diluted and infused slowly — no faster than 1 mg/min — with the patient on a monitor, emergency equipment at hand, and the nurse watching for flushing, hypotension, chest tightness, or dyspnea. Never push it fast because the situation feels urgent; the PCC is what buys the minutes.

Warfarin is the great interaction magnet — it is highly protein-bound and metabolized by CYP450, so antibiotics, amiodarone, azole antifungals, NSAIDs, herbals, alcohol, and even a change in appetite can move the INR. The teaching point students most often get backwards: patients are not told to avoid vitamin K foods. They are told to be consistent. A patient who eats a salad every day is easy to dose; a patient who eats no greens for a month and then goes on a kale kick will swing from bleeding to clotting. Warfarin is also a teratogen — contraindicated in pregnancy (heparin/LMWH do not cross the placenta and are used instead).

DOACs — the modern default

Direct oral anticoagulants skip the liver-synthesis detour and block a clotting protein directly. Dabigatran (Pradaxa) is a direct thrombin inhibitor; apixaban (Eliquis), rivaroxaban (Xarelto), and edoxaban are direct factor Xa inhibitors. The "-xaban" suffix literally names the target: Xa ban. They have a fast onset, few food interactions, fixed dosing, and no routine INR monitoring — which patients love and which quietly removes the safety net that regular lab visits used to provide.

Reversal exists now: idarucizumab (Praxbind) for dabigatran, and andexanet alfa (Andexxa) for apixaban and rivaroxaban. Nursing specifics matter here. Dabigatran must stay in its original bottle or blister — it absorbs moisture and degrades, and the opened bottle is discarded after 4 months; capsules are never opened or crushed (doing so hugely increases absorption). Rivaroxaban's treatment doses are taken with food for absorption. DOACs are renally cleared to varying degrees and need dose adjustment or avoidance in kidney disease, and they are not used for mechanical heart valves or moderate-to-severe mitral stenosis — those patients still get warfarin. Missing doses matters more than it does with warfarin, because the short half-life means an unanticoagulated patient within a day — which is exactly why every DOAC carries a boxed warning that premature discontinuation raises the risk of thrombotic events.

Section 2Antiplatelets and thrombolytics

Two kinds of clot, two kinds of drug

Here is the distinction that makes this section click. Clots in fast-moving arterial blood are built mostly of platelets — they form on a ruptured atherosclerotic plaque and cause heart attacks and most strokes. Clots in slow-moving venous blood are built mostly of fibrin — they form in a leg vein or a fibrillating atrium and cause DVT, PE, and cardioembolic stroke. That is why a patient with a coronary stent goes home on aspirin and clopidogrel while a patient with atrial fibrillation goes home on apixaban. Different clot, different drug. Giving the wrong one is not a small miss.

Aspirin and the P2Y12 inhibitors

Aspirin irreversibly acetylates cyclooxygenase-1 (COX-1) inside the platelet, shutting off thromboxane A2, the signal platelets use to recruit and aggregate one another. "Irreversibly" is the whole story: a platelet has no nucleus, so it cannot make new COX. That single dose disables that platelet for its entire 7–10 day lifespan, and the effect only wears off as the marrow releases fresh platelets. Practical consequences: a low dose (81 mg) is enough for prevention, aspirin is typically held about 7 days before elective surgery, and a patient who took aspirin this morning is still "aspirinized" next week. In suspected MI, the patient chews a non-enteric-coated tablet — 162–325 mg, commonly four 81 mg tablets or one 325 mg tablet — because chewing gets it absorbed in minutes when minutes matter, and an enteric coating defeats the whole point.

Aspirin's costs are GI: dyspepsia, ulcers, and GI bleeding, plus tinnitus as an early sign of salicylate toxicity. It is contraindicated in children and teens with viral illness because of Reye syndrome, and it is avoided in aspirin-exacerbated respiratory disease (the asthma/nasal polyp/aspirin triad).

Clopidogrel (Plavix) blocks the platelet's P2Y12 ADP receptor — a different aggregation signal, which is why aspirin plus clopidogrel is genuinely additive and is called dual antiplatelet therapy (DAPT). Clopidogrel is a prodrug that must be activated by CYP2C19; patients who are poor metabolizers, or who take a strong CYP2C19 inhibitor like omeprazole, get less protection (pantoprazole is the safer PPI pairing). Prasugrel is more potent but is contraindicated after prior stroke/TIA because of intracranial bleeding; ticagrelor is reversible, dosed twice daily, and famously causes dyspnea that is benign but alarming to patients — and its aspirin partner must stay at a low dose. The glycoprotein IIb/IIIa inhibitors (eptifibatide, tirofiban) block the final common step of aggregation and are IV, cath-lab drugs.

The most important DAPT teaching in nursing: a patient with a recent coronary stent must not stop DAPT on their own. Stopping early can thrombose the stent and cause a massive MI. If a dentist or surgeon wants it held, that decision goes back to cardiology — it is not a bedside call, and it is not the patient's call.

Thrombolytics — the clot-busters

Thrombolytics are the one group here that actually dissolves a clot. Alteplase (tPA) and tenecteplase (TNK) are tissue plasminogen activators: they convert plasminogen into plasmin, the enzyme that digests fibrin. That is fantastic when the fibrin is blocking a cerebral artery and catastrophic when the fibrin is the scab holding a recent surgical site together — and the drug cannot tell the difference. Every contraindication follows from that one fact.

Time is the drug. For acute ischemic stroke, IV alteplase is given within 3 hours of last known well, extended to 4.5 hours in selected patients; a noncontrast head CT must first rule out hemorrhage, because giving a thrombolytic into a bleeding brain is fatal. For STEMI, thrombolysis is the fallback when primary PCI cannot be delivered in time, ideally within 30 minutes of arrival. Absolute contraindications cluster around bleeding you cannot compress: any prior intracranial hemorrhage, known cerebral vascular malformation or malignancy, ischemic stroke within 3 months, active internal bleeding, suspected aortic dissection, significant closed head trauma within 3 months.

Nursing during and after a thrombolytic is essentially a bleeding watch with a neuro exam stapled to it. Establish IV access, draw labs, and place any lines before the infusion. Then leave the patient alone: no arterial punctures, no IM injections, no indwelling catheter or NG placement unless truly necessary, hold pressure far longer than usual. Frequent neuro checks and blood pressure — BP is kept below the ordered threshold because hypertension on tPA drives hemorrhagic conversion. A sudden headache, vomiting, altered mental status, or a new neuro deficit means stop the infusion and call. Also keep bleeding precautions in mind: soft toothbrush, electric razor, no rectal temperatures or suppositories, fall precautions.

Section 3Hematopoietic agents and blood products

Pushing the marrow

Every blood cell descends from one hematopoietic stem cell in the bone marrow, and each branch of that family tree has its own growth-factor signal. Drug companies made recombinant copies of those signals, so we can now push a specific line: red cells with erythropoietin, neutrophils with filgrastim, platelets with romiplostim. These are not transfusions — they are instructions. They take days to weeks to work, and they only work if the marrow is capable of responding and has the raw materials on hand.

Erythropoiesis-stimulating agents (ESAs) — epoetin alfa (Epogen, Procrit) and the longer-acting darbepoetin alfa (Aranesp) — replace the erythropoietin a failing kidney can no longer make. They are used mainly in anemia of chronic kidney disease and in chemotherapy-induced anemia. Their boxed warning is one you must understand rather than memorize: pushing hemoglobin too high or too fast increases death, MI, stroke, venous thromboembolism, and tumor progression. Thicker blood clots. So we do not normalize hemoglobin — we use the lowest dose needed to avoid transfusion, and we hold or reduce for a hemoglobin above roughly 11 g/dL or a rise of more than about 1 g/dL in 2 weeks. ESAs also raise blood pressure, so BP is checked before dosing. And ESAs fail without iron: you can shout at the marrow all day, but if there is no iron, ferritin, or transferrin saturation to work with, no hemoglobin gets built. Assess iron stores first. Do not shake the vial — it is a protein and shaking denatures it.

Filgrastim (Neupogen) is granulocyte colony-stimulating factor (G-CSF); it drives the marrow to pump out neutrophils, shortening the neutropenic window after chemotherapy and reducing febrile neutropenia. Pegfilgrastim (Neulasta) is the pegylated once-per-cycle version. Timing is the classic exam point: give it at least 24 hours after the chemotherapy dose, not with it — chemotherapy kills dividing cells, and you have just told the marrow to divide. The signature adverse effect is bone pain, often deep in the sternum and pelvis, and it is a sign the drug is working; it usually responds to acetaminophen or an NSAID (if not contraindicated). Watch for the rare but serious splenic rupture (left upper quadrant or shoulder-tip pain) and ARDS. The nursing outcome is measured with the absolute neutrophil count (ANC), not the white count. Sargramostim (GM-CSF) is broader; romiplostim and eltrombopag are thrombopoietin agonists for immune thrombocytopenia.

Blood products — when you cannot wait for the marrow

Growth factors take days. When a patient is bleeding now, you give them the cells. Each product answers a different question, and matching the product to the deficit is the point. Packed red blood cells carry oxygen. Platelets plug. Fresh frozen plasma supplies all the clotting factors. Cryoprecipitate is the concentrated fibrinogen fraction. Albumin holds volume in the vascular space and carries no clotting or oxygen benefit at all.

Transfusion safety is one of the most protocolized things a nurse does, and for good reason: the deaths come from human identification errors, not from the biology. The bones of it, always following your facility's policy: verify the order and consent; type and crossmatch; a large-bore IV (18–20 g for red cells); only 0.9% normal saline through the Y-tubing, because dextrose lyses cells and lactated Ringer's contains calcium that can clot the line; a two-person verification at the bedside comparing the patient's ID band, the unit, and the paperwork; baseline vital signs. Then start slowly and stay with the patient for the first 15 minutes, because that is when a fatal acute hemolytic reaction announces itself. Recheck vitals per policy, complete each unit within 4 hours, and never add medication to blood.

Learn the reactions by their fingerprints. Acute hemolytic (ABO mismatch): within minutes — fever, chills, flank or back pain, dark urine, hypotension, a sense of impending doom. Febrile nonhemolytic: the most common — a fever rise with chills, from donor leukocytes. Allergic: hives and itching (mild) up to anaphylaxis (more likely in IgA deficiency). TACO (circulatory overload): dyspnea, crackles, JVD, hypertension — too much volume too fast, classically in the small, elderly, or heart-failure patient. TRALI: acute lung injury within 6 hours with dyspnea, hypoxia, and hypotension — and it is a leading cause of transfusion death. TACO and TRALI both drown the patient; the blood pressure is what separates them at the bedside.

The first action for any suspected reaction never changes: stop the transfusion, keep the IV open with normal saline using new tubing, assess and take vitals, and notify the provider and the blood bank. Send the unit, tubing, and the required samples back. Stopping first is not optional — every additional milliliter of an incompatible unit is more hemolysis.

Section 4Blood pressure and antihypertensives

What actually sets the pressure

Every antihypertensive drug in existence works by moving one of two numbers in a single equation:

Blood pressure = cardiac output × systemic vascular resistance. And cardiac output is itself heart rate × stroke volume, where stroke volume depends on preload (the volume coming back), contractility (squeeze), and afterload (what the ventricle pushes against). So there are exactly four levers: drain the tank (diuretics reduce volume → preload), slow and soften the pump (beta-blockers reduce rate and contractility), widen the pipes (vasodilators, CCBs, ACE inhibitors, ARBs reduce resistance), or cut the hormonal signal telling the body to do all of the above (RAAS blockers). Once you see a drug's lever, you can predict both its benefit and its adverse effects without memorizing them separately.

The body defends its pressure with two systems you will fight constantly. The baroreceptor reflex is the fast one: stretch receptors in the carotid sinus and aortic arch sense a pressure drop within seconds and fire the sympathetic system — heart rate up, vessels constricted. This is the reflex that catches you when you stand up, and it is the reflex that produces reflex tachycardia when a vasodilator drops pressure abruptly. The RAAS is the slow one: the kidney senses low perfusion and releases renin, renin converts angiotensinogen to angiotensin I, ACE (largely in the lung) converts it to angiotensin II — a ferocious vasoconstrictor — and angiotensin II triggers aldosterone, which retains sodium and water, and ADH, which retains water. Pressure up. Blocking this loop at any point is the backbone of modern antihypertensive therapy.

Why bother? Because hypertension does its damage silently for decades and then presents as a stroke, a myocardial infarction, heart failure, kidney failure, or blindness. The patient feels nothing. That single fact — that the disease is invisible and the treatment has side effects the patient can feel — is the whole clinical problem, and it is the subject of the next section.

The classes, and what each one costs

Thiazide diuretics (hydrochlorothiazide, chlorthalidone) block the sodium-chloride symporter in the distal convoluted tubule; less sodium means less water, less volume, less preload, and over time some vasodilation. They are cheap, oral, first-line, and their price is metabolic: hypokalemia above all, plus hyponatremia, hypercalcemia, hyperuricemia (gout flares), hyperglycemia, and hyperlipidemia. Loop diuretics (furosemide) are stronger, work at the thick ascending limb of the loop of Henle, keep working in kidney impairment, and are the drug of volume overload and heart failure rather than routine hypertension; they waste potassium and calcium and can cause ototoxicity, especially when pushed IV too fast. Potassium-sparing agents (spironolactone, an aldosterone antagonist) hold potassium back — useful, and the reason spironolactone's main danger is hyperkalemia, along with gynecomastia. Give all diuretics in the morning so the patient is not up all night.

ACE inhibitors (lisinopril — the "-pril" family) block conversion of angiotensin I to II. Less angiotensin II means vasodilation and less aldosterone, and they are protective in heart failure, in diabetic kidney disease, and after MI. ACE also degrades bradykinin, so blocking it lets bradykinin build up — which is why 10–20% of patients get the maddening dry, hacking cough, and why a small number get angioedema, a swelling of the lips, tongue, and airway that is a true emergency. Because less aldosterone means less potassium excretion, expect hyperkalemia, and teach patients to avoid potassium-based salt substitutes. First-dose hypotension is real. ACE inhibitors are contraindicated in pregnancy — fetal renal injury and death.

ARBs (losartan — the "-sartan" family) block the angiotensin II receptor instead of the enzyme. Same downstream benefit, but bradykinin is untouched, so no cough — which is exactly why patients get switched from a "-pril" to a "-sartan." They still cause hyperkalemia and are still contraindicated in pregnancy. ACE inhibitors and ARBs are not combined.

Calcium channel blockers split into two personalities. The dihydropyridines (amlodipine — the "-dipine" family) act on vascular smooth muscle: pure vasodilation, so expect peripheral edema, flushing, headache, and reflex tachycardia. The non-dihydropyridines (diltiazem, verapamil) act on the heart too: they slow conduction and reduce contractility, so expect bradycardia, heart block, worsened heart failure, and verapamil's notorious constipation. Grapefruit juice raises levels of several of these.

Beta-blockers (metoprolol, atenolol — the "-olol" family) blunt sympathetic drive: heart rate down, contractility down, renin release down. Cardioselective agents (metoprolol, atenolol, bisoprolol) prefer beta-1 in the heart; nonselective agents (propranolol) also hit beta-2 and can bronchoconstrict in asthma. Watch for bradycardia, fatigue, and the sneaky one: beta-blockers mask the tachycardia and tremor of hypoglycemia, so a diabetic patient may lose their early warning (sweating still gets through). Never stop a beta-blocker abruptly — rebound tachycardia, hypertension, angina, even MI. Alpha-1 blockers (doxazosin — "-osin") relax vessels and the prostate, and cause a dramatic first-dose orthostatic syncope, so the first dose is given at bedtime. Central alpha-2 agonists (clonidine) reduce central sympathetic outflow, cause sedation and dry mouth, and cause severe rebound hypertension if stopped suddenly — patch and pill both. Direct vasodilators (hydralazine, minoxidil) relax arterioles directly and provoke reflex tachycardia and fluid retention, so they are usually paired with a beta-blocker and a diuretic. Sodium nitroprusside is the ICU emergency drip: near-instant, titrated to an arterial line, light-protected, and it can accumulate as cyanide/thiocyanate with prolonged high-dose use.

Section 5Antihypertensive nursing care

The number you write down is a nursing intervention

An antihypertensive is titrated against a number that you produce. If the number is wrong, the dose is wrong — and a bad technique can move a reading by 10 to 30 mmHg, which is more than most single drugs do. So the technique is not a formality:

• Cuff size is the biggest error. A cuff that is too small reads falsely high; too large reads falsely low. The bladder should encircle about 80% of the arm.
• Patient seated 5 minutes, back supported, feet flat on the floor (crossed legs raise the reading), arm bare and supported at heart level (a dangling arm reads high), and no talking during the reading.
• No caffeine, smoking, or exercise for 30 minutes; bladder empty.
• Take two readings a minute or more apart and average them. Check both arms at the initial visit and use the higher arm thereafter.
• Know your hold parameters before you pour the pill — and if there is no parameter for a drug that can bottom out a pressure, that is a question worth asking, not assuming.

Around the drug itself, follow the class-specific labs and vitals: potassium and renal function for ACE inhibitors, ARBs, spironolactone, and diuretics; apical pulse for a full minute before a beta-blocker or a non-dihydropyridine CCB (commonly hold for a pulse under 60 or per order); daily weight at the same time on the same scale in the same clothing for anyone on a diuretic — because a 1 kg change is about a liter of fluid and weight beats a lung exam for catching it early. Assess ankles for the amlodipine patient, ask about cough for the lisinopril patient, and look at the tongue and lips of anyone new on an ACE inhibitor.

Orthostatic hypotension: the side effect that breaks hips

Nearly every drug in the last section can drop a patient's pressure when they stand up. Orthostatic hypotension is a fall of ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes of standing, and it is not an academic definition — it is the mechanism behind the 3 a.m. fall, the fractured hip, the head bleed on the patient who is also anticoagulated. The physiology is simple: standing dumps about half a liter of blood into the legs, and the baroreceptor reflex normally corrects it in seconds. Beta-blockers blunt the heart-rate half of that reflex, alpha-blockers blunt the vasoconstriction half, and diuretics remove the volume the reflex needs to work with. The patient's own compensation has been pharmacologically disabled.

Measure it properly: BP and pulse supine after a few minutes of rest, then sitting, then standing at 1 minute and again at 3 minutes — and stay with the patient with a gait belt or a chair behind them, because the point of the test is to reproduce a near-faint. Ask about the symptom, not just the number: lightheadedness, gray or tunnel vision, a "wave" on standing.

What you teach is what protects them. Change positions slowly and use the three-stage rise: lie, then sit, then dangle the legs for a full minute, then stand with support. Pump the ankles before rising. Rise from a hot shower or a big meal with extra care — both pool blood away from the brain. First doses and dose increases — especially alpha-blockers — go at bedtime. Call for help before getting up at night; put the light on. Adequate fluid unless restricted, no alcohol on top of the drug, and compression stockings if ordered. And keep the environment honest: bed low, call light in reach, path clear, non-skid footwear.

Adherence: the hardest part of the whole chapter

Roughly half of patients on long-term antihypertensives are not taking them as prescribed a year in, and it is not because they are careless. Look at it from their side: the disease has no symptoms, and the drug has plenty. Before you were treated you felt fine; now you are dizzy, tired, coughing, urinating all day, swollen at the ankles, and possibly having sexual side effects nobody warned you about — all to prevent a stroke you cannot imagine having. Stopping is a rational response to that math. Your job is to change the math, not to lecture.

What actually helps: name the trade honestly ("this doesn't make you feel better — it keeps you from having a stroke"); predict the side effects out loud so that when they arrive they feel expected rather than like a betrayal; teach that a side effect is a reason to call, not to quit (a cough becomes an ARB; edema becomes a lower dose); pair the dose with something they already do every day; hand them a home BP log, because a patient with numbers becomes a participant instead of a subject; simplify to once-daily or combination pills where possible; and ask about cost, plainly, because the most common reason a prescription is not taken is that it was never filled.

And teach the non-negotiables. Never stop a beta-blocker or clonidine abruptly — rebound hypertension, tachycardia, angina, MI, and with clonidine a hypertensive crisis. No potassium salt substitutes on an ACE inhibitor, ARB, or spironolactone. Beware over-the-counter NSAIDs (they blunt antihypertensives and stress the kidney) and decongestants like pseudoephedrine (they raise pressure). Grapefruit juice with certain CCBs. Get up slowly, always. Report a persistent cough, any facial or tongue swelling (go to the ED), a pulse under 60, weight gain over 2–3 lb in a day or 5 lb in a week, or fainting. If pregnancy is possible, discuss it before starting an ACE inhibitor or an ARB. And do not stop taking it because the numbers look good — the numbers look good because of it.

ReferenceWords worth knowing

A quick reference for the terms in this chapter — skim it now, or circle back whenever a word trips you up.

Absolute neutrophil count (ANC)

The number of infection-fighting neutrophils in circulation; the value that tells you whether filgrastim is working and whether a patient is neutropenic.

Afterload

The resistance the ventricle must push against to eject blood; lowered by vasodilators, CCBs, ACE inhibitors, and ARBs.

Angioedema

Rapid swelling of the lips, tongue, face, or airway; an airway emergency and an absolute reason to stop an ACE inhibitor permanently.

Anticoagulant

A drug that prevents fibrin clots from forming or extending — it does not dissolve an existing clot.

Antiplatelet

A drug that keeps platelets from aggregating; the treatment for platelet-rich arterial clots.

aPTT

Activated partial thromboplastin time — the test that follows the intrinsic and common pathways, used to monitor unfractionated heparin.

Baroreceptor reflex

The second-to-second reflex from the carotid sinus and aortic arch that restores blood pressure by raising heart rate and constricting vessels; blunted by many antihypertensives.

Cardiac output

Heart rate × stroke volume; one of the two factors that, with systemic vascular resistance, determines blood pressure.

DAPT (dual antiplatelet therapy)

Aspirin plus a P2Y12 inhibitor, standard after coronary stenting; stopping it early risks stent thrombosis.

DOAC

Direct oral anticoagulant — dabigatran (thrombin) or the "-xaban" agents (factor Xa); no routine monitoring, renally dosed, with specific reversal agents.

Fibrinolysis

Breakdown of a fibrin clot by plasmin; the process thrombolytics accelerate.

Hemostasis

The body's stepwise stopping of bleeding: vasoconstriction, platelet plug, then a reinforcing fibrin mesh.

Heparin-induced thrombocytopenia (HIT)

An immune reaction to heparin, usually 5–10 days in, that drops platelets by ≥ 50% and paradoxically causes thrombosis; all heparin must stop.

High-alert medication

A drug that carries a heightened risk of significant harm when used in error — anticoagulants, thrombolytics, and IV antihypertensives all qualify.

INR

International normalized ratio — the standardized PT used to dose warfarin; usual target 2.0–3.0.

Orthostatic hypotension

A drop of ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes of standing; the mechanism behind medication-related falls.

Preload

The volume of blood returning to and stretching the ventricle before contraction; reduced by diuretics and venodilators.

RAAS

Renin–angiotensin–aldosterone system — the hormonal loop (renin → angiotensin II → aldosterone) that raises blood pressure and that most first-line antihypertensives interrupt.

Systemic vascular resistance (SVR)

The resistance of the arterioles to blood flow; the "width of the pipes" half of the blood pressure equation.

TACO

Transfusion-associated circulatory overload — dyspnea, crackles, JVD, and hypertension from too much volume too fast.

Thrombolytic

A drug such as alteplase that converts plasminogen to plasmin and dissolves fibrin already formed; the highest-bleeding-risk drug class in this chapter.

TRALI

Transfusion-related acute lung injury — dyspnea and hypoxia with hypotension within 6 hours of transfusion; a leading cause of transfusion death.

Cardiovascular Drugs II

The first cardiovascular chapter was about pressure and volume. This one is about the heart muscle itself — the plaque that starves it, the pain that warns you, the pump that fails, and the electricity that keeps it honest. These are the drugs that live on your high-alert list: digoxin with its razor-thin therapeutic window, nitroglycerin that can drop a blood pressure through the floor, amiodarone that quietly scars a lung over months, and statins that most of your patients will take for the rest of their lives. What makes a nurse valuable here is not memorizing every drug — it is knowing which number to check before you push, which symptom means stop, and which sentence, said clearly at discharge, keeps a patient out of the emergency department. That is what this chapter teaches.

Section 1Dyslipidemia drugs

Why we chase a number the patient cannot feel

Dyslipidemia is the quietest diagnosis in the chart. Nobody feels a high LDL. There is no pain, no shortness of breath, no reason to take a pill every night for thirty years — and that is exactly the nursing problem. Low-density lipoprotein (LDL) is the particle that carries cholesterol into the arterial wall, where it oxidizes, recruits inflammatory cells, and builds the plaque you saw in the figure above. High-density lipoprotein (HDL) carries cholesterol back out toward the liver. Triglycerides are a separate problem: at very high levels (roughly above 500 mg/dL) they stop being a cardiac issue and become a pancreatitis issue.

Modern lipid management is not really about hitting a magic number. It is about risk: how likely is this person to have a heart attack or stroke in the next ten years, and how hard should we push? A patient who has already had a myocardial infarction gets high-intensity therapy without much debate. A healthy 45-year-old with a borderline panel gets a conversation. Your job is to make sure that conversation includes the truth: this drug does nothing you will notice, and it works only if you keep taking it.

Statins: the backbone

The HMG-CoA reductase inhibitors — every drug ending in -statin — block the rate-limiting enzyme the liver uses to make cholesterol. Starved of homemade cholesterol, the liver cell puts more LDL receptors on its surface and pulls LDL out of the blood. That is the whole mechanism, and it is remarkably effective: atorvastatin 40–80 mg or rosuvastatin 20–40 mg (the two high-intensity regimens) drop LDL by roughly half. Statins also stabilize existing plaque and damp vascular inflammation, which is why they are started in the hospital during an acute coronary syndrome even when the LDL looks acceptable.

Timing depends on half-life, and students get this backwards constantly. The liver makes most of its cholesterol overnight, so the short-acting statins — simvastatin, lovastatin, fluvastatin — are given in the evening. The long-acting ones — atorvastatin, rosuvastatin, pitavastatin — have half-lives long enough that they can be taken at any consistent hour, which is a gift for adherence.

Statins are metabolized largely by CYP3A4, which is why grapefruit juice matters. Grapefruit inhibits intestinal CYP3A4 and raises drug levels — the effect is real for simvastatin and lovastatin (avoid entirely), modest for atorvastatin (an occasional glass is usually tolerated), and essentially absent for pravastatin, rosuvastatin, and pitavastatin. If a patient loves grapefruit and refuses to give it up, that is a reason to switch statins, not a reason to lose the patient.

Myopathy: the thing you are actually watching for

Muscle complaints are the reason statins get stopped. They sit on a spectrum, and knowing where a patient falls on it is a genuinely useful nursing skill.

Myalgia is muscle aching or weakness with a normal creatine kinase — common, uncomfortable, not dangerous. Myopathy or myositis means symptoms plus a rising creatine kinase (CK). Rhabdomyolysis is the emergency: CK typically more than ten times the upper limit of normal, muscle protein spilling into the blood, and myoglobin clogging the renal tubules into acute kidney injury. The teaching sentence is short and specific: "If your muscles hurt badly, feel weak, and your urine turns the color of cola or tea, stop the drug and call today." Dark urine is the line between an annoyance and a hospitalization.

What do you actually monitor? Less than students expect. Check a lipid panel at baseline and again about 4–12 weeks after starting or changing a dose, then periodically. Check liver enzymes (ALT) at baseline — routine repeat LFTs are no longer recommended, only checked if symptoms of hepatotoxicity appear. Do not draw a routine CK either; get a baseline CK only in high-risk patients (older adults, kidney disease, hypothyroidism, multiple interacting drugs), and draw one whenever a patient reports muscle symptoms. Risk climbs with age, small body frame, renal impairment, untreated hypothyroidism, heavy alcohol use, and CYP3A4 inhibitors like clarithromycin, some azole antifungals, and certain HIV protease inhibitors.

Statins are also traditionally stopped in pregnancy and during breastfeeding. The labeling has been softened to allow individualized use in a narrow group of very-high-risk patients, but the practical bedside expectation remains: a patient who becomes pregnant or is planning pregnancy stops the statin and calls the prescriber. Always ask about pregnancy plans in patients of childbearing potential before discharge.

When a statin is not enough

Statins do the heavy lifting; everything else is an add-on for patients who cannot reach goal, cannot tolerate statins, or have a triglyceride problem instead of an LDL problem.

Section 2Angina and acute coronary syndrome

Supply versus demand, and nothing else

Every antianginal drug ever invented does one of two things: it increases the oxygen supply reaching the myocardium, or it lowers the myocardial oxygen demand. That is the entire logic of this section, and if you hold onto it, the drug list organizes itself.

Demand rises with heart rate, contractility, and wall tension (which reflects preload and afterload). So a drug that slows the heart, softens the squeeze, or drains the ventricle before it contracts will lower demand. Supply depends on coronary flow, which happens mostly during diastole — another reason slowing the heart helps, since a slower heart spends proportionally more time in diastole.

Stable angina is predictable: it comes on with exertion or emotion and goes away with rest or nitroglycerin, because a fixed plaque cannot pass enough blood when demand climbs. Unstable angina is new, worsening, or occurs at rest — the plaque has ruptured and a clot is forming. Vasospastic (Prinzmetal) angina is coronary spasm in an artery that may be nearly normal, classically at rest and in the early morning. Acute coronary syndrome (ACS) is the umbrella over unstable angina, NSTEMI, and STEMI — and the distinction between them lives in the troponin and the ST segment, not in how loudly the patient complains.

Nitrates: the drug your patient carries in a pocket

Nitrates are converted to nitric oxide in vascular smooth muscle, which relaxes it. At usual doses the effect is mostly venodilation: blood pools in the veins, less returns to the heart, preload falls, the ventricle wall is under less tension, and demand drops. At higher doses arteries dilate too, lowering afterload, and the coronary arteries themselves relax — which is why nitrates are excellent for vasospastic angina.

Sublingual nitroglycerin teaching is one of the most testable and most genuinely life-saving conversations you will have. Sit or lie down first — this drug drops blood pressure and people faint standing in kitchens. Place one 0.4 mg tablet under the tongue (or one spray onto or under the tongue) and let it dissolve; do not swallow it, do not chew it. A tingling or burning sensation may occur but its absence does not mean the tablet is dead. If the pain is unimproved or worsening 5 minutes after the first dose, call 911 — then continue up to a total of three doses, 5 minutes apart, while help is on the way. That order matters: the old teaching of "three doses, then call" delayed too many people.

Storage sinks a lot of prescriptions. Tablets belong in their original amber glass bottle, tightly capped, away from heat, light, and moisture — not in a pill organizer, not in a pocket against body heat, not in a steamy bathroom cabinet or a hot car. Once the bottle is opened, replace it about every 6 months. The metered spray is more stable and often the better choice for someone who rarely uses it. Expect headache — it is the most common effect, it means the drug is working, and acetaminophen usually handles it. Warn about dizziness and orthostasis.

Other nitrate forms have their own traps. Transdermal patches and long-acting isosorbide mononitrate/dinitrate cause tolerance if given around the clock, so the regimen builds in a nitrate-free interval of 10–12 hours — usually the patch goes on in the morning and comes off in the evening. Remove the old patch before applying a new one, rotate sites, and wear gloves so you do not dose yourself with a headache. Intravenous nitroglycerin is titrated to pain and blood pressure and traditionally requires non-PVC (polyethylene or glass) tubing, because the drug adsorbs to standard PVC.

The rest of the antianginal cabinet

Beta blockers (metoprolol, atenolol, bisoprolol) are first-line for chronic stable angina and reduce mortality after MI: they cut heart rate and contractility, so demand falls and diastolic filling time lengthens. Hold and reassess for bradycardia, hypotension, or acute decompensated heart failure, and never stop them abruptly — rebound tachycardia and angina can trigger an infarct. One classic exception: avoid beta blockers in cocaine-associated chest pain, where unopposed alpha stimulation can worsen coronary spasm; benzodiazepines and nitrates are used instead.

Calcium channel blockers dilate coronary and systemic arteries. Amlodipine and other dihydropyridines mainly vasodilate (ankle edema, reflex tachycardia, flushing). Verapamil and diltiazem also slow the heart and reduce contractility, which makes them useful when a beta blocker is not tolerated — but combining them with a beta blocker risks serious bradycardia and heart block. CCBs are the drugs of choice for vasospastic angina. Ranolazine is a later-line option for chronic angina that inhibits the late sodium current; it barely touches heart rate or blood pressure, which is its selling point, but it prolongs the QT interval and is never used for an acute attack.

The ACS bundle

When a patient with crushing chest pain hits the door, a familiar set of drugs goes in fast. Older courses teach the mnemonic MONA (morphine, oxygen, nitrates, aspirin) — keep the letters, but update the practice: morphine has been deprioritized (it may blunt antiplatelet absorption and can mask ongoing ischemia), and oxygen is given only if the SpO₂ is below about 90%, because routine oxygen in a non-hypoxic patient offers no benefit and may cause harm. Aspirin remains the one drug that saves lives in the first minutes.

Section 3Heart failure drugs

What a failing heart is actually doing

In heart failure with reduced ejection fraction (HFrEF), the ventricle cannot eject enough blood, and the body — sensing what looks like low volume — does exactly the wrong thing. The sympathetic nervous system fires, raising heart rate and afterload. The renin–angiotensin–aldosterone system (RAAS) switches on, retaining sodium and water and driving vasoconstriction. Over months, angiotensin II and aldosterone remodel the ventricle into a dilated, fibrotic, poorly functioning bag. The compensation becomes the disease.

That is why modern heart failure therapy looks strange at first glance: the cornerstone drugs are ones that slow the heart and block the very hormones the body is producing. We are not helping the heart work harder. We are calling off the neurohormonal siege. And the payoff is not just symptom relief — these are mortality drugs, which is why titrating them to target doses matters more than almost anything else on the outpatient side.

The four pillars

Guideline-directed medical therapy for HFrEF now rests on four drug classes, all started early and titrated up as tolerated. Students should be able to name all four cold.

Around the pillars sit useful extras. Hydralazine plus isosorbide dinitrate is added for patients who remain symptomatic (with proven benefit in self-identified Black patients) and is a fallback when ACE inhibitors and ARBs cannot be used because of renal function or hyperkalemia. Ivabradine slows the SA node's funny current for patients in sinus rhythm with a heart rate still at or above 70 despite a maximally tolerated beta blocker; it causes luminous visual phenomena (phosphenes) that alarm patients unless you warn them. Vericiguat is an option after a worsening event.

The ACE inhibitor profile deserves its own list, because it recurs everywhere: a persistent dry, hacking cough from bradykinin accumulation (switch to an ARB — ARBs do not cause it), angioedema (a true emergency; airway first; a lifetime contraindication to the whole class and to ARNI), hyperkalemia, first-dose hypotension (give the first dose at bedtime, hold diuretics if possible), a rise in creatinine, and fetal toxicity.

Diuretics: symptom control, not survival

Diuretics are the drugs patients feel working — and they are also the ones that do not, by themselves, prolong life. They exist to pull water off a congested patient who cannot breathe.

Loop diuretics (furosemide, bumetanide, torsemide) block the Na-K-2Cl transporter in the thick ascending limb and are powerful enough to work even when the GFR is poor. Their costs are electrolytic: hypokalemia, hypomagnesemia, hyponatremia, hypocalcemia, metabolic alkalosis, hyperuricemia, hyperglycemia, and dehydration with orthostatic hypotension. Ototoxicity — tinnitus and hearing loss, usually reversible — is linked to rapid IV administration and high doses, which is why IV furosemide is pushed slowly (commonly no faster than about 20 mg/min) and why loop plus aminoglycoside is a bad pairing. Loops are sulfonamide-derived; ethacrynic acid is the alternative for a true sulfa allergy. Give the morning dose early and the second dose by mid-afternoon so the patient is not up all night.

Thiazides (hydrochlorothiazide, chlorthalidone) are weaker and fail below a GFR of roughly 30. Metolazone is the exception used for diuretic resistance: it is given about 30 minutes before the loop dose, and the combination is potent enough to strip potassium dangerously fast — watch the K⁺ closely. Potassium-sparing agents (spironolactone, eplerenone, triamterene, amiloride) go the other way and retain potassium.

Digoxin and its narrow window

Digoxin is the oldest drug in this chapter and the one most likely to hurt someone. It inhibits the sodium–potassium ATPase in cardiac myocytes. Sodium builds up inside the cell, the sodium–calcium exchanger runs less efficiently, intracellular calcium rises, and the contraction gets stronger — a positive inotropic effect. Separately, digoxin increases vagal tone at the AV node, slowing conduction and heart rate — a negative chronotropic and negative dromotropic effect. That combination is why it is used both for symptomatic HFrEF (fewer hospitalizations, but no mortality benefit) and for rate control in atrial fibrillation, particularly in a hypotensive patient who cannot tolerate a beta blocker.

The therapeutic range is classically 0.5–2.0 ng/mL, but in heart failure the modern target is a narrower 0.5–0.9 ng/mL — higher levels increase mortality without adding benefit. Draw the level as a trough, at least 6–8 hours after the last dose (12 hours or immediately before the next dose is cleanest); a level drawn too early looks alarmingly high and reflects distribution, not toxicity.

The signs of toxicity are famous because they are exam gold and because they are easy to miss at 3 a.m.

That last row is the concept students most often miss. Potassium and digoxin compete for the same binding site on the Na⁺/K⁺ ATPase. When potassium falls — and what drug does your heart failure patient also take? A loop diuretic — digoxin binds more avidly and the patient can become toxic with a "therapeutic" level on the lab report. A normal digoxin level does not rule out digoxin toxicity. Interacting drugs raise levels too: amiodarone, verapamil, quinidine, and clarithromycin all push digoxin up, and the dose is typically cut roughly in half when amiodarone is added.

Treatment of significant toxicity is digoxin immune Fab (DigiFab) — antibody fragments that bind digoxin and pull it out of tissue — used for life-threatening arrhythmia, severe hyperkalemia from acute overdose, or hemodynamic instability. After Fab is given, total serum digoxin levels become uninterpretable (they measure bound drug), so treat the patient, not the number. Correct hypokalemia and hypomagnesemia; in acute overdose with hyperkalemia, calcium is generally avoided.

Section 4Antiarrhythmics

The five phases, and why anyone should care

Antiarrhythmics are frightening to learn because the classification looks arbitrary. It is not. Each class is named for the ion channel it blocks, and each channel owns a phase of the action potential. Learn the phases once and the classes become obvious.

In a working ventricular myocyte: Phase 0 is the rapid upstroke — sodium rushes in and the cell depolarizes. Phase 1 is a brief notch as potassium leaks out. Phase 2 is the long plateau unique to cardiac muscle — calcium enters and drives contraction, and this is what keeps the heart from tetanizing. Phase 3 is repolarization as potassium floods out. Phase 4 is the resting membrane potential — except in pacemaker cells (SA and AV nodes), where phase 4 is a slow spontaneous drift upward (the "funny current") that sets the heart rate, and where phase 0 is driven by calcium, not sodium. That last detail explains why calcium channel blockers act on nodes while sodium channel blockers act on the working muscle.

The Vaughan Williams classes

Two drugs that deserve their own paragraph

Amiodarone is the most useful and most toxic antiarrhythmic in the building. It blocks potassium channels (class III) but also has sodium-blocking, beta-blocking, and calcium-blocking activity — it is all four classes in one molecule, which is why it works on almost anything. It is also lipophilic and stored in fat, giving it a half-life of roughly 40–60 days: side effects can appear months after starting and persist months after stopping. Monitoring is a systems tour — pulmonary fibrosis (the feared one; baseline chest X-ray and pulmonary function, then investigate any new dry cough or dyspnea), thyroid dysfunction in either direction because the molecule is loaded with iodine (baseline and periodic TSH), hepatotoxicity (LFTs), corneal microdeposits (usually benign; annual eye exam; report visual halos), and blue-gray skin discoloration with severe photosensitivity (sunscreen and covering clothing — a real quality-of-life issue patients are not warned about often enough). It raises digoxin and warfarin levels, so both doses come down when amiodarone goes up. IV amiodarone can cause hypotension and phlebitis — use a central line or large vein and an inline filter for continuous infusions.

Adenosine is the drug that makes new nurses gasp. Given for stable SVT, it briefly blocks the AV node and the monitor shows a few seconds of asystole before sinus rhythm resumes. Its half-life is under 10 seconds, so it must be given as a rapid IV push — 6 mg, immediately followed by a 20 mL saline flush, ideally through a proximal large-bore line with the arm elevated (a two-syringe or stopcock technique). Warn the patient first: they will feel chest pressure, flushing, and a sense of doom for a few seconds. Have the defibrillator nearby and a rhythm strip running — the strip is diagnostic even when the drug does not convert.

Section 5Cardiovascular monitoring and nursing care

The apical pulse: a 60-second skill that prevents harm

Before digoxin and before beta blockers and non-dihydropyridine calcium channel blockers, you take an apical pulse. Not a radial pulse, not the monitor's number, and not for fifteen seconds times four. Place the diaphragm at the fifth intercostal space, midclavicular line — the point of maximal impulse — and count for a full minute. The full minute is not ritual: these are exactly the patients with irregular rhythms and a pulse deficit, where weak beats generate a heart sound but no radial pulse, and a 15-second sample can be wrong by 20 beats.