Pharmacology by Class and Suffix

In depth

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How drug names are built

Generic names in the United States are United States Adopted Names (USAN); they share their stems with the World Health Organization’s International Nonproprietary Names (INN), and the USAN list notes the few stems that differ. A name is a unique prefix plus a stem that signals the class: lisinopril and enalapril share -pril because both inhibit angiotensin-converting enzyme. Brand names follow no such rule, which is one reason the NCLEX uses generic names and why a stem is the fastest way to place a drug you have never seen.

Most stems are suffixes, but some are prefixes (cef- for cephalosporins, gli- for antidiabetics such as glipizide) and some sit inside the name (-vir- in antivirals). The AMA’s cumulative USAN stem list runs to several hundred stems and substems and says it is not exhaustive. Substems narrow the class: -tinib means a tyrosine kinase inhibitor, -citinib a Janus kinase inhibitor and -brutinib a Bruton kinase inhibitor.

Monoclonal antibodies were named with -mab from 1990. Older names carry a source syllable before it: -ximab (chimeric, such as infliximab), -zumab (humanized, such as trastuzumab) and -umab (human, such as adalimumab). Because the -mab list had grown so long, the INN and USAN programmes replaced the stem for new antibodies in late 2021: -tug (unmodified antibody), -bart (engineered antibody), -mig (bispecific or multispecific) and -ment (fragment). Names already adopted keep -mab, so -mab drugs will be on the exam for years.

Heart and blood pressure: the why behind the checks

-olol. β-blockers slow the SA node and AV conduction and reduce contractility, so the check before each dose is an apical pulse for a full minute plus BP; Open RN teaches holding for an apical rate under 60 unless the order gives other parameters. They blunt the tachycardia of hypoglycemia and can mask the tachycardia of thyrotoxicosis. Stopping abruptly can worsen angina or cause MI, so the Toprol-XL label tapers over 1 to 2 weeks. β₁ selectivity is not absolute, so clients with asthma need the lowest dose and a bronchodilator at hand. Labetalol (-alol) and carvedilol also block α receptors.

-pril. ACE inhibitors block angiotensin II formation and the breakdown of bradykinin. Bradykinin build-up is the usual explanation for the dry cough and angioedema; the Zestril label says angioedema can occur at any time during treatment, is more frequent in Black patients, and can affect the intestine, presenting as abdominal pain. Less aldosterone means potassium retention, so salt substitutes and potassium supplements are avoided. The boxed warning is fetal toxicity, and a -pril is not given within 36 hours of sacubitril/valsartan.

-sartan. ARBs block the angiotensin II receptor and leave bradykinin alone. In the Cozaar label’s trials in clients who had coughed on an ACE inhibitor, cough recurred in 17% and 29% on losartan against 69% and 62% on lisinopril. Angioedema is still reported, and the fetal-toxicity warning and potassium monitoring are the same.

-dipine. Dihydropyridine calcium channel blockers dilate arterioles: headache, flushing, palpitations and dose-related ankle edema (about 11% at amlodipine 10 mg against under 1% on placebo, amlodipine label). Verapamil (-pamil) and diltiazem act mainly on the heart and are held for bradycardia. Grapefruit raises some calcium channel blocker levels, but the amlodipine label reports no effect.

-statin. Statins block HMG-CoA reductase. Clients report unexplained muscle pain, tenderness or weakness, especially with fever or unusual tiredness; risk rises at 65 or older, with uncontrolled hypothyroidism, kidney impairment, higher doses and drugs such as gemfibrozil, cyclosporine and some azoles and macrolides. The Lipitor label asks for liver tests before starting and when clinically indicated, not on a schedule; atorvastatin can be taken at any time of day; more than 1.2 L of grapefruit juice daily is not recommended; it is stopped in pregnancy.

-azosin. α₁-blockers relax arteriolar and prostatic smooth muscle and treat BPH and hypertension. The first dose and each increase can cause syncope; the doxazosin label says not to drive for 24 hours after either. They cause intraoperative floppy iris syndrome, so clients tell the eye surgeon before cataract surgery. Tamsulosin has no -azosin stem but belongs to the class.

Worked example. A client who started lisinopril 3 weeks ago has swollen lips and a hoarse voice. Which action first? Protect the airway: call for help and prepare for airway support, then stop the drug and notify the provider. A cough is bothersome; swelling of the lips, tongue or voice box is an emergency, and it can appear weeks or years into therapy.

Stomach and diabetes classes

-prazole. Proton pump inhibitors are taken before meals. Long-term daily use raises the risk of C. difficile diarrhea, hip, wrist and spine fractures, low magnesium, low B12 and fundic gland polyps, so the omeprazole label asks for the lowest dose for the shortest time; omeprazole is avoided with clopidogrel. -tidine. H₂ blockers such as famotidine accumulate when creatinine clearance is under 60 mL/min, where the label reduces the dose and reports confusion, delirium, seizures and QT prolongation.

-glitazone. Pioglitazone sensitizes tissues to insulin but retains fluid: the Actos boxed warning is heart failure, and starting it in NYHA class III or IV failure is contraindicated. Teach daily weights and reporting of swelling or breathlessness; liver tests are done before starting.

-gliptin. DPP-4 inhibitors raise incretin levels. Teach the client to report severe persistent abdominal pain (pancreatitis), severe joint pain and blisters (bullous pemphigoid). Sitagliptin is reduced to 50 mg at an eGFR of 30 to 44 and 25 mg under 30.

-gliflozin. SGLT2 inhibitors make the kidney spill glucose, so urine glucose always reads positive and cannot monitor control. Risks: volume depletion and acute kidney injury, genital yeast infections (more common in women), urosepsis, Fournier gangrene and ketoacidosis with glucose that may be below 250 mg/dL. The Jardiance label withholds the drug at least 3 days before surgery or prolonged fasting.

-glutide. GLP-1 agonists slow gastric emptying and increase glucose-dependent insulin release: nausea, pancreatitis, gallbladder disease and kidney injury from dehydration. The boxed warning is thyroid C-cell tumors in rodents; a personal or family history of medullary thyroid carcinoma or MEN 2 is a contraindication. Ozempic is weekly; a missed dose is given within 5 days or skipped. Aspiration under anesthesia has been reported, so clients tell the anesthesia team.

Hypoglycemia comes mainly from insulin and sulfonylureas (glipizide, glyburide; the gli- prefix marks every antidiabetic, not only sulfonylureas); the newer labels advise lowering the insulin or sulfonylurea dose when combined.

Worked example. A client on empagliflozin, NPO since midnight for surgery, has nausea, abdominal pain and deep rapid breathing; glucose is 190 mg/dL. Which action first? Report suspected ketoacidosis and expect ketones and a blood gas. A near-normal glucose does not rule it out with this class.

Anti-infectives: one class at a time

Before a first dose, ask what the reaction was (rash or anaphylaxis), obtain ordered cultures, and stay with the client for the first minutes of a new IV antibiotic. Any antibiotic can cause C. difficile diarrhea, even 2 months later (azithromycin label). Penicillins (-cillin) and cephalosporins (cef-) are β-lactams; cross-reactivity is low, but a history of anaphylaxis is reported before the dose.

Aminoglycosides. Gentamicin (-micin, from Micromonospora) and tobramycin (-mycin, from Streptomyces) damage kidneys, inner ear and nerves. The gentamicin label says to avoid prolonged peaks above 12 mcg/mL and troughs above 2 mcg/mL, monitor urinalysis, creatinine and hearing, avoid furosemide and ethacrynic acid, and warn of fetal harm. Macrolides (azithromycin) prolong QT, especially with low K⁺ or Mg²⁺, bradycardia or other QT drugs, and can injure the liver and worsen myasthenia gravis.

-floxacin. The boxed warning covers tendinitis and rupture, peripheral neuropathy, CNS effects and worsened myasthenia gravis; tendon risk is higher over 60, with corticosteroids and after a kidney, heart or lung transplant; the label reserves fluoroquinolones for sinusitis, uncomplicated cystitis and bronchitis flares only when nothing else works. They also cause glucose swings, QT prolongation and photosensitivity. Ciprofloxacin is taken 2 hours before or 6 hours after antacids, sucralfate and calcium, iron or zinc products, and not with dairy alone.

-cycline. Tetracyclines stain developing teeth (last half of pregnancy to age 8), cause photosensitivity and esophageal ulcers (most cases were taken right before bed), lose absorption with antacids, calcium, magnesium, iron and bismuth, and may make oral contraceptives less effective. The doxycycline label still allows it under 8 for severe illness such as anthrax or Rocky Mountain spotted fever.

-azoles and metronidazole. Fluconazole (-conazole) can injure the liver, prolong QT and raise warfarin, sulfonylurea and phenytoin levels. Metronidazole (-nidazole) causes a disulfiram-like reaction with alcohol during therapy and for at least 3 days after, a metallic taste, neuropathy and a raised INR.

-vir. Acyclovir and valacyclovir can cause acute kidney failure (older age, dehydration, kidney disease) and confusion in older adults; hydrate and watch creatinine. Oseltamivir starts within 48 hours of flu symptoms for 5 days and is not a substitute for the annual vaccine.

Worked example. A 68-year-old taking prednisone and ciprofloxacin reports sudden heel pain. Which action? Advise rest of the limb and holding the next dose, and notify the provider: this is the boxed tendon warning, and both age and steroids raise the risk.

Nervous system and mood

-triptan. Triptans are 5-HT1 agonists that constrict cranial vessels. The Imitrex label contraindicates them in coronary or peripheral vascular disease, prior stroke or TIA, uncontrolled hypertension, within 24 hours of an ergot or another triptan, and within 2 weeks of an MAO-A inhibitor. Chest, throat or jaw tightness is common and usually not cardiac. Tablets may be repeated after 2 hours, to 200 mg in 24 hours; use on 10 or more days a month can cause medication-overuse headache.

-azepam, -zolam. Benzodiazepines enhance GABA. The lorazepam boxed warning covers profound sedation, respiratory depression, coma and death with opioids, plus misuse and withdrawal on abrupt stopping, so the check is respiratory rate, sedation level and what else is on board. Flumazenil reverses them but can cause seizures, especially after long-term use or with a tricyclic overdose. USAN lists -azepam (lorazepam, diazepam); alprazolam and midazolam end in -zolam.

-oxetine. Fluoxetine-type antidepressants take weeks to work. The boxed warning is suicidal thoughts in children, adolescents and young adults (no increase over 24). Serotonin syndrome is the key interaction (triptans, tramadol, linezolid, MAOIs): wait 14 days after an MAOI before starting and 5 weeks after fluoxetine before starting an MAOI. Not every SSRI carries the stem (sertraline, citalopram); atomoxetine is an ADHD drug; duloxetine is an SNRI.

Other CNS stems: -triptyline and -pramine (tricyclics: anticholinergic effects, deadly in overdose), -peridol and -peridone (antipsychotics: extrapyramidal effects), -pine (a tricyclic structure, not one class: quetiapine and clozapine are antipsychotics, carbamazepine an anticonvulsant). See Mental Health and Toxidromes and Antidotes.

Worked example. A client on fluoxetine is prescribed sumatriptan and later has agitation, tremor, sweating and a temperature of 38.9 °C. The nurse suspects serotonin syndrome, holds both drugs and notifies the provider.

Biologics and targeted cancer drugs

-mab. Many antibodies suppress immunity. The Humira (adalimumab) boxed warning covers serious infections, including tuberculosis and invasive fungal infection, and lymphoma: test for latent TB before and during therapy, screen for hepatitis B, do not start during an active infection, stop for a serious infection, and avoid live vaccines. Injection site reactions are among the most common effects; rotate sites. IV antibodies can cause infusion reactions (fever, chills, hypotension): stop the infusion and assess. -cept names receptor fusion proteins (etanercept binds TNF).

-tinib. Kinase inhibitors are oral targeted cancer drugs. Imatinib is taken with a meal and a large glass of water; it causes fluid retention (weigh regularly), low blood counts (CBC weekly for the first month), liver injury (monthly liver tests) and fetal harm (contraception to 14 days after), and strong CYP3A4 inducers lower its level. -parib names PARP inhibitors (olaparib).

Worked example. A client starting adalimumab asks why a skin or blood TB test is needed first. The nurse explains that the drug can wake up latent TB, which must be treated before therapy starts, and that fever or cough during therapy is reported promptly.

Antidotes and reversal: matching drug to rescue

Reversal pairs are tested as matching items and as first actions. Protamine binds heparin and only partly neutralizes enoxaparin. Vitamin K restores warfarin’s missing clotting factors over hours, so serious bleeding also needs four-factor prothrombin complex concentrate (4F-PCC). Idarucizumab binds dabigatran. For apixaban and rivaroxaban, 4F-PCC is used, because andexanet left the US market in December 2025 (see High-Alert Meds).

Naloxone and flumazenil are competitive antagonists, so the original drug can outlast them: keep monitoring and redose as ordered. Flumazenil can precipitate seizures and is not used when a benzodiazepine was given for a life-threatening problem such as status epilepticus (lorazepam label). Glucagon bypasses the β receptor in β-blocker poisoning, digoxin immune fab binds digoxin, acetylcysteine replenishes glutathione after acetaminophen overdose, and calcium gluconate counters magnesium toxicity. Doses are on Toxidromes and Antidotes and Obstetric Emergencies.

Worked example. A client on IV heparin has a platelet count that fell from 220,000 to 95,000/mm³ on day 6 with a new swollen calf. Is protamine the answer? No: this is heparin-induced thrombocytopenia, a clotting problem. Stop all heparin, including flushes, and expect a non-heparin anticoagulant.

Suffix traps and look-alike names

Other shared endings: -mycin covers aminoglycosides (tobramycin), macrolides (azithromycin), vancomycin and clindamycin, so learn the drug, not just the ending. -tidine (famotidine) is an H₂ blocker, while -tine alone is not a stem. -olol is β-only, but labetalol (-alol) and carvedilol also block α. pred- marks prednisone and prednisolone derivatives.

Look-alike names cause errors that a stem cannot prevent. The FDA Name Differentiation Project recommends Tall Man letters for pairs such as niCARdipine and NIFEdipine (both -dipine), glipiZIDE and glyBURIDE, hydrALAZINE and hydrOXYzine, predniSONE and prednisoLONE, traZODone and traMADol, buPROPion and busPIRone, and DOBUTamine and DOPamine. Read the whole name, compare it with the order three times, and ask the pharmacist when the indication does not fit.

Worked example. An order reads nicardipine 20 mg by mouth for a client with hypertension; the dispensed bottle says NIFEdipine. What should the nurse do? Hold the dose and clarify with the pharmacy: same class and stem, but a different drug.

More stems worth knowing

Exam pearls

• β-blocker: apical pulse for a full minute before the dose; hold under 60 unless parameters differ; never stop abruptly.
• ACE inhibitor cough: report, and expect a switch to an ARB; lip or tongue swelling at any time: airway first.
• -pril, -sartan: avoid potassium salt substitutes and pregnancy.
• Statin: unexplained muscle pain or dark urine is reported promptly.
• SGLT2 inhibitor: ketoacidosis can occur with a near-normal glucose; hold at least 3 days before surgery.
• GLP-1 agonist: ask about medullary thyroid cancer and MEN 2; report severe abdominal pain.
• Aminoglycoside: watch creatinine, urine output and hearing; the gentamicin label avoids troughs above 2 mcg/mL.
• Fluoroquinolone: tendon pain means stop and report; separate from antacids and minerals.
• Tetracycline: not under 8 or in pregnancy; plenty of fluid, not right before bed; sunscreen.
• Metronidazole: no alcohol during therapy and for 3 days after.
• Benzodiazepine plus opioid: watch respiratory rate and sedation; flumazenil can cause seizures.
• SSRI plus triptan or tramadol: watch for serotonin syndrome.
• TNF-blocking -mab: TB test before starting; no live vaccines.
• Same stem, different drug: niCARdipine is not NIFEdipine.