Free FPGEE Practice Test: 100 Questions With Explanations

Answer: C. Angiotensin II drives aldosterone synthesis in the zona glomerulosa of the adrenal cortex by increasing aldosterone synthase (CYP11B2). Aldosterone then helps the kidney hold on to sodium and water, which supports blood volume and pressure.

Why the other choices are wrong:

• A. The adrenal medulla is not where aldosterone is made; aldosterone synthase activity is described in the zona glomerulosa.
• B. The posterior pituitary releases ADH, not aldosterone.
• D. Juxtaglomerular cells release renin, which starts the cascade. They are upstream of angiotensin II, not its target for aldosterone production.

Remember: Renin comes from the kidney; aldosterone comes from the zona glomerulosa.

Source: StatPearls, Physiology, Renin Angiotensin System (updated Feb 21, 2026) — renin source; angiotensin II and aldosterone actions

Answer: A, B, C. Aldosterone increases sodium reabsorption in the distal nephron and collecting duct, largely through epithelial sodium channels (ENaC). The net result is sodium retention with potassium and hydrogen ion secretion. That is why excess aldosterone tends to cause low potassium, and why blocking aldosterone can raise potassium.

Why the other choices are wrong:

• D. Aldosterone does the opposite. It retains sodium, so urinary sodium excretion falls.

Remember: Aldosterone: keep sodium, lose potassium and hydrogen ions.

Source: Pflügers Archiv 2024: The renin angiotensin aldosterone system — aldosterone actions in the distal nephron

Answer: C. StatPearls lists increased activity of the sodium–hydrogen antiporter in the proximal convoluted tubule as one of angiotensin II's direct effects. This adds to the sodium retention that aldosterone produces further down the nephron.

Why the other choices are wrong:

• A. Epithelial sodium channels are increased by aldosterone in the collecting duct, not inhibited by angiotensin II.
• B. Natriuretic peptides promote sodium loss, which runs against the effect described.
• D. Aquaporin-2 insertion is an ADH effect in the collecting duct, not the proximal tubule mechanism described for angiotensin II.

Remember: Angiotensin II works on two levels: directly in the proximal tubule and indirectly through aldosterone.

Source: StatPearls, Physiology, Renin Angiotensin System (updated Feb 21, 2026) — Actions of angiotensin II

Answer: B. Vitamin B12 is a coenzyme for two reactions: methylmalonyl-CoA to succinyl-CoA, and homocysteine to methionine. When B12 is lacking, both methylmalonic acid and homocysteine build up. Folate is also needed for the homocysteine-to-methionine step, so homocysteine rises in folate deficiency too. The methylmalonic acid rise is what separates B12 deficiency.

Why the other choices are wrong:

• A. This pattern fits folate deficiency, where homocysteine rises but the B12-dependent methylmalonyl-CoA step still works.
• C. Normal values of both markers argue against either deficiency.
• D. B12 deficiency raises homocysteine; it does not lower it.

Remember: High methylmalonic acid is the B12 signal. Homocysteine alone does not tell B12 and folate apart.

Source: American Family Physician 2003: Vitamin B12 Deficiency — Methylmalonic acid; homocysteine; Selhub J, et al. PNAS 2007;104:19995–20000 — Introduction: B12-dependent reactions

Answer: B. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, the enzyme that converts HMG-CoA to mevalonate. Blocking this step reduces the body's own cholesterol production.

Why the other choices are wrong:

• A. Lipoprotein lipase hydrolyzes triglycerides in circulating lipoproteins; it is not the statin target.
• C. Cyclooxygenase is the target of NSAIDs, not statins.
• D. Acetylcholinesterase breaks down acetylcholine; it has no role in the mevalonate pathway.

Remember: Statin = HMG-CoA reductase inhibitor = less mevalonate.

Source: Atorvastatin calcium prescribing information (DailyMed) — Clinical Pharmacology 12.1, Mechanism of Action

Answer: D. Homocysteine is converted to methionine using vitamin B12 and folic acid as cofactors. This is why homocysteine can rise with a shortage of either vitamin.

Why the other choices are wrong:

• A. Vitamin K is needed for clotting-factor carboxylation, and vitamin C for collagen synthesis. Neither drives this step.
• B. Thiamine and riboflavin serve other enzymes in energy metabolism.
• C. Vitamins D and A act largely through nuclear receptors, not as cofactors for this reaction.

Remember: Homocysteine to methionine needs both B12 and folate.

Source: NIH Office of Dietary Supplements, Vitamin B12: Health Professional Fact Sheet — methionine synthase and homocysteine; NIH Office of Dietary Supplements, Folate: Health Professional Fact Sheet — folate and homocysteine-to-methionine conversion

Answer: C. All mycoplasmas lack a cell wall. Beta-lactams such as amoxicillin work by interfering with cell wall synthesis, so Mycoplasma is inherently resistant to them. CDC describes treatment with other antibiotic classes, such as macrolides, with alternatives such as doxycycline when a patient is not improving on a macrolide.

Why the other choices are wrong:

• A. The resistance is intrinsic to the missing cell wall, not an enzyme.
• B. Mycoplasma pneumoniae is a bacterium.
• D. Spore formation describes organisms such as Clostridioides difficile, not Mycoplasma.

Remember: No cell wall, no beta-lactam activity.

Source: CDC, Clinical Care of Mycoplasma pneumoniae Infection — Treatment

Answer: C. C. difficile forms spores, and alcohol-based hand sanitizer does not kill them. That is why CDC stresses gloves and soap-and-water handwashing in C. difficile situations.

Why the other choices are wrong:

• A. C. difficile is a spore-forming bacterium, not an enveloped virus.
• B. CDC states that alcohol-based hand sanitizer does not cause antibiotic resistance.
• D. C. difficile has a cell wall; the relevant feature is spore formation.

Remember: Spores shrug off alcohol. Remove them mechanically.

Source: CDC, Hand hygiene fact sheet for healthcare providers — C. difficile and alcohol-based hand sanitizer; CDC, Preventing C. diff — Healthcare precautions; handwashing

Answer: C. In type I hypersensitivity, IgE binds high-affinity FcεRI receptors on mast cells. When the allergen cross-links that bound IgE, mast cells degranulate and release preformed mediators such as histamine, followed by newly made lipid mediators. The timing is minutes, which fits this patient.

Why the other choices are wrong:

• A. Immune-complex deposition is a different, slower mechanism.
• B. A 48-to-72-hour T-cell response describes a delayed reaction, not an immediate one.
• D. Complement activation on red cells describes antibody-mediated cell destruction, not an allergic reaction to food.

Remember: Minutes after exposure plus IgE on mast cells equals type I.

Source: Novel Approaches in the Inhibition of IgE-Induced Mast Cell Reactivity (PMC) — FcεRI engagement and mediator release

Answer: D. MMR is a live attenuated vaccine. CDC states that people with most forms of altered immunocompetence should not receive live vaccines, including MMR, because uncontrolled replication of the attenuated organism can create a safety risk. The other listed vaccines are non-live.

Why the other choices are wrong:

• A. The injectable influenza vaccine named here is inactivated, not live.
• B. Hepatitis B vaccine is not a live attenuated vaccine.
• C. Td contains toxoids, not live organisms.

Remember: Severe immunosuppression is the moment to stop and check for live vaccines.

Source: CDC, Altered Immunocompetence — live, attenuated viral and bacterial vaccines: safety

Answer: C. In diabetic ketoacidosis, lack of insulin allows lipolysis. Free fatty acids go to the liver and are oxidized to ketone bodies. These ketoacids are buffered by bicarbonate, so bicarbonate falls and unmeasured anions accumulate. The result is a high anion gap metabolic acidosis.

Why the other choices are wrong:

• A. The patient stopped insulin; the problem is too little insulin, not too much.
• B. Bicarbonate loss from diarrhea is a classic cause of normal anion gap acidosis, which does not fit this history.
• D. Rapid breathing here is compensation for metabolic acidosis, not a primary respiratory problem.

Remember: DKA = no insulin, ketoacids, high anion gap.

Source: StatPearls, Biochemistry, Anion Gap — HAGMA and DKA; Diagnosis and treatment of DKA and HHS (PMC) — Anion gap formula and normal value; Nursing Critical Care: Assessing the anion gap — Normal and non-anion-gap acidosis

Answer: D. The acetylcysteine label explains it: at therapeutic doses, acetaminophen is mostly conjugated to sulfate and glucuronide, and the small amount of reactive CYP2E1 metabolite is detoxified by glutathione. In a large overdose, those conjugation pathways saturate, more reactive metabolite forms, glutathione is depleted, and the metabolite binds liver cell proteins, causing necrosis.

Why the other choices are wrong:

• A. The injury is metabolic, not a blood-flow effect.
• B. Acetaminophen is not converted to salicylate.
• C. The problem is the reactive metabolite, not failure of renal excretion.

Remember: Overdose overwhelms conjugation and glutathione. That is where acetylcysteine comes in.

Source: Acetylcysteine injection, prescribing information (DailyMed) — Clinical pharmacology: acetaminophen overdose; acetylcysteine treatment

Answer: 143 mL. Use C1V1 = C2V2. 70% × V1 = 20% × 500 mL, so V1 = 10,000 ÷ 70 = 142.86 mL, which rounds to 143 mL. Because water is added to a final volume rather than in a fixed amount, contraction on mixing does not change the answer.

Common wrong answers:

• 1750: Inverting the ratio (500 × 70 ÷ 20) gives more than the final volume, which is impossible.
• 357: That is roughly the water added, not the stock alcohol.

Remember: Put the stronger solution's percentage on the side with the unknown volume.

Source: Castleport worked calculation (inputs stated in the question)

Answer: 20 mEq. For a monovalent ion, 1 mmol = 1 mEq. 1.5 g = 1,500 mg. 1,500 mg ÷ 74.5 mg/mmol = 20.13 mmol, so about 20 mEq of potassium.

Common wrong answers:

• 0.02: Dividing grams by the molecular weight without converting to milligrams gives mol, not mmol.
• 40: Doubling as if KCl gave two potassium ions; it gives one potassium ion per formula unit.

Remember: mEq = mg ÷ molecular weight × valence.

Source: Castleport worked calculation (inputs stated in the question)

Answer: 300 micrograms. A 1:1,000 (w/v) ratio means 1 g in 1,000 mL, which is 1 mg/mL. So 0.3 mL contains 0.3 mg, which is 300 micrograms.

Common wrong answers:

• 30: This drops a factor of 10; 0.3 mg equals 300 mcg, not 30.
• 3000: This treats 1:1,000 as 10 mg/mL.

Remember: 1:1,000 = 1 mg/mL.

Source: Castleport worked calculation (inputs stated in the question)

Answer: 308 mOsm/L. 0.9% w/v = 0.9 g per 100 mL = 9 g/L. 9 ÷ 58.5 = 0.1538 mol/L. Two particles per formula unit gives 0.3077 osmol/L, or 307.7 mOsm/L, which rounds to 308.

Common wrong answers:

• 154: This forgets that NaCl dissociates into two particles.
• 31: This uses 0.9 g/L instead of 9 g/L.

Remember: Osmolarity = (g/L ÷ MW) × number of particles × 1,000.

Source: Castleport worked calculation (inputs stated in the question)

Answer: C. For a weak acid, ionized ÷ un-ionized = 10^(pH − pKa) = 10^(6.5 − 4.5) = 100. So 100 parts are ionized for every 1 part un-ionized: 100 ÷ 101 ≈ 99% ionized.

Why the other choices are wrong:

• A. This is the answer for a weak base under the same conditions, or a sign reversal.
• B. 50% ionization happens only when pH equals pKa.
• D. About 91% corresponds to a one-unit difference (ratio of 10), not two units.

Remember: Each pH unit away from the pKa multiplies the ratio by 10.

Source: Castleport worked calculation (inputs stated in the question)

Answer: A. 22 lb ÷ 2.2 = 10 kg. 10 kg × 15 mg/kg/day = 150 mg/day. Every 8 hours means 3 doses a day, so 150 ÷ 3 = 50 mg per dose.

Why the other choices are wrong:

• B. This skips the weight entirely.
• C. This uses 22 as kilograms (22 × 15 ÷ 3).
• D. This is the total daily dose, not the per-dose amount.

Remember: Convert to kg first, then split the daily dose.

Source: Castleport worked calculation (inputs stated in the question)

Answer: A. Codeine labeling states that its metabolism varies with CYP2D6 genotype, which can increase exposure to the active metabolite morphine. Life-threatening respiratory depression and death have occurred in children, many of whom had evidence of ultra-rapid metabolism.

Why the other choices are wrong:

• B. Genotype affects metabolism to morphine, not gut absorption.
• C. The danger in ultra-rapid metabolizers is too much active morphine, not too little activity.
• D. The concern is increased conversion, not unchanged excretion.

Remember: More CYP2D6 activity means more morphine from the same codeine dose.

Source: Codeine sulfate tablets, prescribing information (DailyMed) — Boxed warning; contraindications 4; warnings 5.6; Acetaminophen and codeine phosphate tablets, prescribing information (DailyMed) — Boxed warning: hepatotoxicity; ultra-rapid metabolism of codeine

Answer: A. The acetylcysteine label describes acetaminophen as extensively metabolized in the liver, principally to sulfate and glucuronide conjugates that are excreted in urine. Only a small fraction goes through CYP2E1 to the reactive intermediate. Conjugation adds polar groups, making the drug easier to excrete.

Why the other choices are wrong:

• B. CYP2E1 handles only a small fraction at therapeutic doses; this pathway grows in overdose.
• C. Ester hydrolysis is not the main pathway for acetaminophen.
• D. Most of the dose is conjugated first.

Remember: Therapeutic dose: mostly conjugation. Overdose: conjugation saturates.

Source: Acetylcysteine injection, prescribing information (DailyMed) — Clinical pharmacology: acetaminophen overdose; acetylcysteine treatment

Answer: D. The clopidogrel boxed warning states that its antiplatelet effect depends on conversion to an active metabolite by the cytochrome P450 system, principally CYP2C19. That is why patients with two loss-of-function CYP2C19 alleles form less active metabolite.

Why the other choices are wrong:

• A. CYP2C19 activates clopidogrel; it does not inactivate an already-active drug.
• B. Activation is hepatic and enzymatic, not acid-driven.
• C. Renal glucuronidation is not the activation step described.

Remember: Clopidogrel is a prodrug that needs CYP2C19.

Source: Clopidogrel tablets, prescribing information (DailyMed) — Boxed warning; clinical pharmacology 12.5 (pharmacogenomics)

Answer: D. The warfarin label states that the S-enantiomer has 2 to 5 times more anticoagulant activity than the R-enantiomer. It also describes stereoselective metabolism: S-warfarin mainly by CYP2C9, R-warfarin by CYP1A2 and CYP3A4. Chirality matters clinically because interacting drugs may affect one enantiomer more than the other.

Why the other choices are wrong:

• A. Both are active; S is more potent.
• B. Their potency and metabolic pathways differ.
• C. S-warfarin is cleared mainly by CYP2C9.

Remember: Warfarin's potency lives mostly in the S-enantiomer.

Source: Warfarin sodium tablets, prescribing information (DailyMed PDF) — Clinical pharmacology: enantiomer potency and metabolism; Warfarin sodium tablets, prescribing information (DailyMed) — Drug interactions (CYP450); dosing by indication; INR monitoring

Answer: B. The warfarin label states that the more potent S-enantiomer is metabolized by CYP2C9 and that CYP2C9 inhibitors can increase warfarin exposure and INR. Fluconazole inhibits CYP2C9. Less S-warfarin clearance means more anticoagulant effect.

Why the other choices are wrong:

• A. CYP3A4 (with CYP1A2) handles mainly R-warfarin, the less potent enantiomer.
• C. Protein-binding displacement is not the mechanism described for this interaction.
• D. Fluconazole is an antifungal; this is not its described mechanism.

Remember: Warfarin plus a CYP2C9 inhibitor: expect the INR to climb.

Source: Warfarin sodium tablets, prescribing information (DailyMed) — Drug interactions (CYP450); dosing by indication; INR monitoring; Akamatsu H, et al. J Pharm Health Care Sci. 2023;9:11 — Background and Discussion (fluconazole, CYP2C9, S-warfarin)

Answer: D. Varenicline is a partial agonist at α4β2 receptors, with lower maximal efficacy than nicotine. It partly reproduces nicotine's effects while occupying the receptor so nicotine cannot fully activate it.

Why the other choices are wrong:

• A. Its maximal efficacy is below nicotine's, so it is not a full agonist producing a stronger effect.
• B. It is not described as an irreversible antagonist.
• C. It stimulates the receptor partially; it does not reduce activity below baseline.

Remember: Partial agonist: some effect, plus a ceiling that blocks the full agonist.

Source: Rollema H, et al. Neuropharmacology 2007 (varenicline pharmacology) — Abstract

Answer: A, B, C. Lisinopril labeling describes persistent nonproductive cough, presumably from reduced breakdown of bradykinin; hyperkalemia, especially with renal insufficiency, diabetes, or potassium-sparing diuretics; and angioedema, which requires stopping the drug.

Why the other choices are wrong:

• D. ACE inhibitors tend to raise potassium by reducing aldosterone, not lower it.

Remember: ACE inhibitor triad to remember: cough, high potassium, angioedema.

Source: Lisinopril tablets, prescribing information (DailyMed) — Precautions: hyperkalemia; cough; Lisinopril tablets, prescribing information (DailyMed) — Highlights: warnings and drug interactions; patient counseling: angioedema

Answer: B. The linezolid label identifies it as a reversible, nonselective inhibitor of monoamine oxidase, giving it potential to interact with serotonergic and adrenergic agents. Blocking serotonin breakdown while an SSRI blocks reuptake can push serotonin too high.

Why the other choices are wrong:

• A. Blocking serotonin receptors would not produce serotonin toxicity.
• C. The interaction described is MAO inhibition, not enzyme induction.
• D. Linezolid is an antibacterial, not an SSRI.

Remember: Linezolid acts like a weak MAO inhibitor. Treat it that way.

Source: Linezolid injection, prescribing information (DailyMed) — Warnings: serotonin syndrome; clinical pharmacology: MAO inhibition

Answer: D. In overdose, hepatic glutathione is depleted and the toxic metabolite (NAPQI) binds liver cells. Acetylcysteine replenishes glutathione and may also act as a glutathione substitute that combines directly with the toxic metabolite. The label notes it reduces the extent of liver injury and works best when given early.

Why the other choices are wrong:

• A. Reducing absorption is not acetylcysteine's mechanism.
• B. It is not described as a CYP2E1 inhibitor.
• C. It does not work by enhancing renal excretion.

Remember: Acetylcysteine refills the glutathione tank.

Source: Antidote for acetaminophen poisoning: N-acetylcysteine (review) — Abstract; Acetylcysteine injection, prescribing information (DailyMed) — Clinical pharmacology: acetaminophen overdose; acetylcysteine treatment

Answer: A, B, C. Nitroglycerin sublingual labeling lists use of PDE-5 inhibitors (such as avanafil, sildenafil, tadalafil, or vardenafil) and soluble guanylate cyclase stimulators as contraindications. Combining these drugs with a nitrate can cause dangerous hypotension.

Why the other choices are wrong:

• D. Acetaminophen is not listed as a contraindication for nitroglycerin.

Remember: Nitrate plus PDE-5 inhibitor or sGC stimulator: do not combine.

Source: Nitroglycerin sublingual tablets, prescribing information (DailyMed) — Highlights: dosage and contraindications

Answer: D. Allopurinol is a xanthine oxidase inhibitor. One of azathioprine's inactivation pathways runs through xanthine oxidase, so blocking it raises exposure to active metabolites. The label advises reducing azathioprine to about one-third to one-quarter of the usual dose when given with allopurinol.

Why the other choices are wrong:

• A. The drugs do interact through xanthine oxidase inhibition.
• B. Increasing the dose would add to the toxicity risk.
• C. This is not the labeled adjustment.

Remember: Azathioprine plus allopurinol: cut the azathioprine dose substantially.

Source: Azathioprine tablets, prescribing information (DailyMed) — Warnings: TPMT/NUDT15; precautions: drug interactions (xanthine oxidase inhibitors)

Answer: C. FDA's Orange Book explains that enteric coatings are used when a drug may be destroyed or inactivated by gastric juice or may irritate the gastric mucosa. The coating delays release until the tablet has passed through the stomach. These are delayed-release products.

Why the other choices are wrong:

• A. This is the opposite of the coating's purpose.
• B. Enteric coating is not designed for chewing; chewing would defeat it.
• D. Delayed release is not the same as extended release.

Remember: Enteric coating = delayed release past the stomach.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: A. The Orange Book states that solutions and powders for reconstitution are different dosage forms, so they are not pharmaceutical equivalents. They may be pharmaceutical alternatives and are not rated AP to each other, even if they reach the same concentration before injection.

Why the other choices are wrong:

• B. AP applies to therapeutically equivalent injectables; these two are not equivalents.
• C. Different dosage forms are not automatically interchangeable.
• D. AB ratings apply to pharmaceutical equivalents that meet bioequivalence requirements.

Remember: Solution versus powder is a dosage-form difference.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: 30 days. For first-order decay, t90 = ln(100/90) ÷ k = 0.1054 ÷ k. 0.1054 ÷ 0.0035 per day = 30.1 days, which rounds to 30 days.

Common wrong answers:

• 198: This uses 0.693 ÷ k, which is the half-life, not t90.
• 3: This drops a decimal place in the rate constant.

Remember: t90 = 0.105 ÷ k for first-order degradation.

Source: Castleport worked calculation (inputs stated in the question)

Answer: C. Levothyroxine labeling states that iron and calcium supplements and antacids can decrease its absorption and that levothyroxine should be taken at least 4 hours before or after drugs known to interfere with absorption.

Why the other choices are wrong:

• A. Calcium reduces absorption; it does not improve it.
• B. The label specifically names calcium as interfering.
• D. The label calls for an empty stomach, not food.

Remember: Levothyroxine and calcium or iron: four hours apart.

Source: Levothyroxine sodium tablets, prescribing information (DailyMed) — Dosage and administration 2.1; patient counseling

Answer: B. The alendronate label states that other beverages (including mineral water), food, and some medications are likely to reduce absorption, and that even orange juice or coffee has been shown to markedly reduce it. Taking it with plain water, first thing in the morning, protects the small amount that is absorbed.

Why the other choices are wrong:

• A. The instruction is about absorption, not metabolic activation.
• C. Coffee and juice reduce absorption; they do not raise it.
• D. The instruction is not about activating a coating.

Remember: Alendronate is easy to block. Plain water only.

Source: Alendronate sodium tablets, prescribing information (DailyMed) — Dosage and administration; patient counseling 17.2

Answer: 6 hours. t½ = 0.693 ÷ k = 0.693 ÷ 0.1155 per hour = 6.0 hours.

Common wrong answers:

• 9: This uses 1 ÷ k (8.7 hours) instead of 0.693 ÷ k.
• 0.08: This multiplies 0.693 by k instead of dividing.

Remember: t½ = 0.693 ÷ k.

Source: Castleport worked calculation (inputs stated in the question)

Answer: B. Each half-life closes half of the remaining gap to steady state: 50% after one, 75% after two, 87.5% after three, and 93.75% after four. The fraction is 1 − (1/2)^n. That is why steady state is commonly treated as reached after about 4 to 5 half-lives.

Why the other choices are wrong:

• A. This is after one half-life.
• C. This is after two half-lives.
• D. This is after three half-lives.

Remember: Four half-lives ≈ 94% of steady state.

Source: Castleport worked calculation (inputs stated in the question)

Answer: 735 mg. Loading dose = Vd × target concentration. Vd = 0.7 L/kg × 70 kg = 49 L. 49 L × 15 mg/L = 735 mg.

Common wrong answers:

• 10.5: This leaves out the patient's weight.
• 1050: This uses 70 L as the volume of distribution.

Remember: Loading dose depends on volume of distribution, not clearance.

Source: Castleport worked calculation (inputs stated in the question)

Answer: D. Levothyroxine labeling notes that, because of its long half-life, the peak therapeutic effect at a given dose may not be attained for 4 to 6 weeks. That is also why dose changes are judged after several weeks, not days.

Why the other choices are wrong:

• A. The long half-life makes a same-day peak effect implausible.
• B. Effect builds toward steady state; it does not peak and fade after dose one.
• C. Timing matters for absorption, but the delay to full effect reflects the half-life.

Remember: Long half-life, slow road to steady state: judge levothyroxine in weeks.

Source: Levothyroxine sodium tablets, USP, prescribing information (DailyMed) — Dosage and administration; laboratory tests; drug interactions

Answer: C. The Orange Book defines bioequivalence as the absence of a significant difference in the rate and extent to which the active ingredient or moiety becomes available at the site of drug action, given at the same molar dose under similar conditions in an appropriately designed study.

Why the other choices are wrong:

• A. Pharmaceutical equivalents do not need identical inactive ingredients.
• B. Shape and color may differ among therapeutically equivalent products.
• D. Price and manufacturer have nothing to do with the definition.

Remember: Bioequivalence = same rate and extent of availability.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: B. Carbamazepine's boxed warning links HLA-B*1502 with serious skin reactions (SJS/TEN) and says patients with ancestry in genetically at-risk populations should be screened before starting. Allele-positive patients should not be treated unless the benefit clearly outweighs the risk.

Why the other choices are wrong:

• A. CYP2C19 testing relates to drugs such as clopidogrel, not this boxed warning.
• C. TPMT testing relates to thiopurines such as azathioprine.
• D. Genetic screening is central to this boxed warning.

Remember: Carbamazepine + HLA-B*1502 = screen first.

Source: Carbamazepine tablets, prescribing information (DailyMed) — Boxed warning; warnings: SJS/TEN and HLA-B*1502

Answer: D. Clopidogrel forms less active metabolite in CYP2C19 poor metabolizers and has a reduced effect on platelets. Its boxed warning says to consider another platelet P2Y12 inhibitor in patients identified as poor metabolizers.

Why the other choices are wrong:

• A. Genotype directly affects activation, which is the point of the warning.
• B. Clopidogrel labeling advises avoiding omeprazole; it does not boost activation.
• C. The labeled suggestion is another P2Y12 inhibitor, not aspirin alone.

Remember: CYP2C19 poor metabolizer on clopidogrel: consider a different P2Y12 inhibitor.

Source: Clopidogrel tablets, prescribing information (DailyMed) — Boxed warning; clinical pharmacology 12.5 (pharmacogenomics); Clopidogrel bisulfate tablets, prescribing information (DailyMed PDF) — Highlights: CYP2C19 inhibitors (omeprazole, esomeprazole)

Answer: C. By alligation: 20% − 10% = 10 parts of the 5% ointment, and 10% − 5% = 5 parts of the 20% ointment, for 15 parts total. 5/15 × 300 g = 100 g of 20% ointment (and 200 g of 5%). Check: 100 × 0.20 + 200 × 0.05 = 20 + 10 = 30 g of drug, which is 10% of 300 g.

Why the other choices are wrong:

• A. This does not reach 10%; 50 g of 20% plus 250 g of 5% gives 22.5 g of drug, or 7.5%.
• B. Equal parts would give 12.5%, not 10%.
• D. This is the amount of the 5% ointment.

Remember: In alligation, the parts sit diagonally across from each strength.

Source: Castleport worked calculation (inputs stated in the question)

Answer: C. 60 g × 2% = 1.2 g of drug needed. 1.2 g ÷ 0.10 = 12 g of the 10% ointment, plus 48 g of base.

Why the other choices are wrong:

• A. This is the grams of drug, not the grams of stock ointment.
• B. This halves the correct amount.
• D. This would give a 5% ointment.

Remember: Find the drug amount first, then divide by the stock strength.

Source: Castleport worked calculation (inputs stated in the question)

Answer: A, B, D. 21 CFR 1306.05(a) requires every controlled-substance prescription to be dated and signed on the day it is issued and to show the patient's full name and address; the drug name, strength, dosage form, and quantity; directions for use; and the practitioner's name, address, and DEA registration number.

Why the other choices are wrong:

• C. A diagnosis is not a general federal requirement. The rule does require a medical-need note on prescriptions for gamma-hydroxybutyric acid (1306.05(c)). States may add their own requirements.
• E. Date of birth is not listed in 1306.05(a).

Remember: Federal elements cover who the patient is, what was ordered, and who ordered it.

Source: 21 CFR 1306.05, Manner of issuance of prescriptions (eCFR) — Paragraphs (a) and (c)

Answer: B. 21 CFR 1306.12(a) states plainly that refilling a prescription for a Schedule II controlled substance is prohibited. Each fill needs its own valid prescription.

Why the other choices are wrong:

• A. No refills are permitted for Schedule II under federal law.
• C. A phone authorization does not create a refill for Schedule II.
• D. The 6-month rule applies to Schedule III and IV refills, not Schedule II.

Remember: Schedule II: no refills, ever, under federal law.

Source: 21 CFR 1306.12, Refilling prescriptions; issuance of multiple prescriptions (eCFR) — Paragraphs (a) and (b)

Answer: A. 21 CFR 1306.12(b) lets an individual practitioner issue multiple prescriptions for a total of up to a 90-day supply of a Schedule II substance. Conditions include a legitimate medical purpose, written instructions on each prescription (other than one meant to be filled immediately) giving the earliest fill date, no undue risk of diversion, and permission under state law.

Why the other choices are wrong:

• B. Schedule II refills are prohibited.
• C. Phone authorization cannot create Schedule II refills.
• D. Open-ended refills are not allowed for Schedule II.

Remember: Schedule II: separate prescriptions with do-not-fill-before dates, up to 90 days total.

Source: 21 CFR 1306.12, Refilling prescriptions; issuance of multiple prescriptions (eCFR) — Paragraphs (a) and (b)

Answer: D. 21 CFR 1306.22(a) says a Schedule III or IV prescription may not be filled or refilled more than six months after its issue date, and may not be refilled more than five times. March 1 plus six months is September 1, so on September 15 the remaining refills have expired.

Why the other choices are wrong:

• A. Remaining refills expire at the six-month limit.
• B. A partial refill is still a refill after the limit.
• C. No further fills are allowed after six months.

Remember: Schedule III–IV: 5 refills or 6 months, whichever comes first.

Source: 21 CFR 1306.22, Refilling of prescriptions (eCFR) — Paragraph (a)

Answer: C. 21 CFR 1305.03 requires a DEA Form 222 or its electronic equivalent for each distribution of a Schedule I or II controlled substance, with limited exceptions. DEA guidance confirms this applies to transfers between registrants.

Why the other choices are wrong:

• A. An invoice alone does not satisfy the Schedule I–II order requirement.
• B. A verbal agreement is not a federal record.
• D. Registration status does not remove the order-form requirement.

Remember: Schedule I–II changing hands between registrants: Form 222 or electronic equivalent.

Source: 21 CFR 1305.03, Distributions requiring a Form 222 or a digitally signed electronic order (eCFR) — Section text

Answer: A, B, C. DEA summarizes the Act's retail rules: a daily sales limit of 3.6 grams per purchaser regardless of the number of transactions; blister packaging of nonliquid forms with no more than two dosage units per blister (unit-dose packets or pouches where blister packs are not technically feasible); and a 9-gram 30-day retail purchase limit.

Why the other choices are wrong:

• D. The federal law regulates over-the-counter sale; it does not require a prescription. Some states add stricter rules.

Remember: CMEA: 3.6 g a day, 9 g in 30 days, blister packs.

Source: DEA Diversion Control Division, Combat Methamphetamine Epidemic Act: general information — Daily sales limit; blister packaging; DEA Diversion Control Division, Preventing the Retail Diversion of Pseudoephedrine — 30-day retail purchase limit

Answer: A. Medicare Part D is the voluntary outpatient prescription drug benefit, created by the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 and effective January 1, 2006. It is delivered through private plans that contract with the federal government.

Why the other choices are wrong:

• B. Part A is not the outpatient prescription drug benefit.
• C. Part B is not the program created as the outpatient prescription drug benefit; that is Part D.
• D. Part C (Medicare Advantage) plans may include drug coverage, but the drug benefit itself is Part D.

Remember: D is for drugs.

Source: Congressional Research Service, Medicare Part D Prescription Drug Benefit (R40611) — Overview; dual eligibles

Answer: A. The Medicare Modernization Act made Part D the primary source of drug coverage for people covered by both Medicare and Medicaid. Medicaid, a joint federal and state program, may still cover certain drugs that Medicare excludes by law, depending on the state.

Why the other choices are wrong:

• B. Medicaid is not the primary drug payer for dual eligibles, though it may cover some Part D-excluded drugs.
• C. Part A is not an outpatient drug benefit.
• D. Dual eligibles have drug coverage through Part D.

Remember: Dual eligible: Part D first, Medicaid for some exclusions.

Source: Congressional Research Service, Medicare Part D Prescription Drug Benefit (R40611) — Overview; dual eligibles; Medicare Interactive, Medicaid and Medicare Part D overview — Medicaid definition; drugs excluded from Part D

Answer: A. Difference in cost = $12,000 − $8,000 = $4,000. Difference in effect = 4.0 − 3.5 = 0.5 QALY. ICER = $4,000 ÷ 0.5 = $8,000 per QALY gained.

Why the other choices are wrong:

• B. This is Drug A's average cost per QALY ($12,000 ÷ 4.0), not the incremental ratio.
• C. This is the cost difference without dividing by the effect difference.
• D. This comes from summing costs ($20,000), which is not the incremental comparison.

Remember: Incremental means difference over difference.

Source: Castleport worked calculation (inputs stated in the question)

Answer: B. To prevent one event you treat 25 patients. 25 × $600 = $15,000.

Why the other choices are wrong:

• A. This divides $600 by 25 instead of multiplying.
• C. This is the cost for one patient.
• D. This multiplies by 10 instead of 25.

Remember: Cost per event prevented = NNT × cost per patient.

Source: Castleport worked calculation (inputs stated in the question)

Answer: A, C. CDC notes that healthcare professionals use precautions such as a gown and gloves while caring for patients with C. diff. Public health guidance also calls for disinfecting surfaces with a product effective against C. difficile spores (EPA List K) or bleach per label instructions.

Why the other choices are wrong:

• B. Alcohol-based hand sanitizer does not kill C. difficile spores.
• D. Gloves are a core measure; sanitizer does not replace them.

Remember: C. diff: gown and gloves, and a sporicidal disinfectant for surfaces.

Source: CDC, Preventing C. diff — healthcare precautions; US EPA, Registered Antimicrobial Products Effective Against C. difficile Spores (List K) — sporicidal products and label directions

Answer: D. Relative risk (RR) = 0.06 ÷ 0.10 = 0.6. Relative risk reduction = 1 − RR = 0.4, or 40%. The absolute risk reduction is 10% − 6% = 4%.

Why the other choices are wrong:

• A. 4% is the absolute risk reduction.
• B. 0.6 (60%) is the relative risk, not the reduction.
• C. 25 is the NNT (1 ÷ 0.04), not a percentage reduction.

Remember: RRR = 1 − RR. ARR = the plain difference in rates.

Source: Understanding the Intention-to-treat Principle in RCTs (PMC) — ITT definition; relative risk and RRR; Castleport worked calculation (inputs stated in the question)

Answer: D. Absolute risk reduction = 0.15 − 0.12 = 0.03. NNT = 1 ÷ 0.03 = 33.3. The convention is to round NNT up, giving 34 patients.

Why the other choices are wrong:

• A. This confuses the 3% absolute reduction with the NNT.
• B. 33.3 rounds up, not down, by the usual NNT convention.
• C. This uses 1 ÷ 0.01.

Remember: NNT = 1 ÷ ARR, rounded up.

Source: StatsDirect, Number Needed to Treat — NNT from risk difference; rounding up; Castleport worked calculation (inputs stated in the question)

Answer: D. $1,200,000 ÷ $150,000 = 8. Inventory turned over about 8 times in the year. Higher turnover generally means less cash tied up on the shelves.

Why the other choices are wrong:

• A. This divides inventory by cost of goods sold.
• B. This does not follow from the figures given; 1,200,000 ÷ 150,000 is 8.
• C. This misplaces a decimal.

Remember: Turnover = cost of goods sold ÷ average inventory.

Source: Castleport worked calculation (inputs stated in the question)

Answer: A. The Orange Book states that it contains public information and advice and does not mandate which products are purchased, prescribed, dispensed, or substituted. It notes that therapeutic equivalence is a scientific judgment, while generic substitution may involve policy administered by the states.

Why the other choices are wrong:

• B. The Orange Book says it does not mandate substitution.
• C. It does not prohibit substitution; it helps states and pharmacists decide.
• D. The Orange Book says FDA evaluates therapeutic equivalence only for multisource prescription drug products.

Remember: FDA rates equivalence; states decide substitution rules.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: A. AHRQ describes teach-back as a way to check understanding by asking patients to state in their own words what they need to know or do. Framing it as checking the explanation, not testing the patient, keeps it respectful.

Why the other choices are wrong:

• B. The question invites an explanation, not a yes or no.
• C. The technique described is specifically teach-back.
• D. Reflective listening restates the patient's words; here the patient restates the instructions.

Remember: Teach-back checks your explanation, not the patient.

Source: AHRQ, Use the Teach-Back Method: Tool 5 — Tool description

Answer: A. AHRQ describes the show-me method as the companion to teach-back: it confirms that patients can follow specific instructions, and uses using an inhaler as its example. Watching the technique reveals errors that a verbal 'I understand' can hide.

Why the other choices are wrong:

• B. A yes/no check often misses misunderstanding.
• C. Written material helps but does not confirm technique.
• D. Repeating instructions does not confirm the patient can do it.

Remember: For devices, have the patient show you.

Source: AHRQ, Use the Teach-Back Method: Tool 5 — Tool description

Answer: B. A 50% relative risk reduction can describe a fall from 20% to 10% or from 2% to 1%. The absolute rates, and the absolute risk reduction, show how much benefit a patient can actually expect. Relative figures alone can make a benefit look bigger than it is.

Why the other choices are wrong:

• A. The name says nothing about the size of the benefit.
• C. The number of sites does not convert a relative effect into an absolute one.
• D. The source matters for credibility, but you still need absolute rates to judge benefit.

Remember: Always ask: 50% of what?

Source: Randomized trial of dentists' understanding of absolute vs relative risk (PMC) — Introduction: same RRR, different absolute rates

Answer: C. Intention-to-treat analysis keeps each participant in the group to which they were originally assigned: 'once randomized, always analyzed.' This preserves the balance created by randomization and avoids overstating a treatment effect.

Why the other choices are wrong:

• A. Excluding them is closer to a per-protocol approach.
• B. Moving them breaks randomization.
• D. ITT does not assume an outcome; it analyzes by assignment.

Remember: Once randomized, always analyzed.

Source: Understanding the Intention-to-treat Principle in RCTs (PMC) — ITT definition; relative risk and RRR

Answer: A. AHRQ's toolkit encourages finding out whether patients have difficulty paying for medicine and, when patients are taking medicines incorrectly, trying to find out why. Cost is a common, fixable barrier that patients may be reluctant to raise.

Why the other choices are wrong:

• B. A warning without exploring the reason rarely solves the problem.
• C. Assuming discontinuation is appropriate skips the conversation.
• D. Coordination with the prescriber may be needed, but only after understanding the barrier.

Remember: When a refill stops, ask about cost.

Source: AHRQ Health Literacy Universal Precautions Toolkit, 3rd edition — Medicine review; difficulty paying for medicine

Answer: A, B, C. The ibuprofen boxed warning covers increased risk of serious cardiovascular thrombotic events and serious gastrointestinal adverse events, and it states that ibuprofen is contraindicated in the setting of CABG surgery.

Why the other choices are wrong:

• D. The label says to avoid ibuprofen in severe heart failure unless the benefits are expected to outweigh the risk of worsening heart failure.

Remember: NSAID boxed warning: heart, gut, and no use around CABG surgery.

Source: Ibuprofen tablets, prescribing information (DailyMed) — Boxed warning; warnings: heart failure and edema

Answer: B. Acetaminophen–codeine labeling warns that most cases of acetaminophen liver injury are associated with doses exceeding 4,000 mg per day and often involve more than one acetaminophen-containing product. Duplicate acetaminophen in cold products is a common hidden source.

Why the other choices are wrong:

• A. Vitamin C is not the relevant safety issue here.
• C. Dosage form preference does not address the duplication risk.
• D. Brand status is irrelevant; the ingredient is what matters.

Remember: Before recommending an OTC combination, look for hidden acetaminophen.

Source: Acetaminophen and codeine phosphate tablets, prescribing information (DailyMed) — Boxed warning: hepatotoxicity; ultra-rapid metabolism of codeine

Answer: A. Ibuprofen labeling notes that fluid retention and edema have been seen with NSAIDs and that ibuprofen may blunt the cardiovascular effects of diuretics, ACE inhibitors, and angiotensin receptor blockers. Together these can worsen heart failure.

Why the other choices are wrong:

• B. NSAIDs blunt diuretic effects; they do not strengthen them.
• C. NSAIDs are not described as causing excessive hypotension here.
• D. New weight gain and edema after starting an NSAID point to the NSAID first.

Remember: New edema after starting an NSAID in heart failure: suspect the NSAID.

Source: Ibuprofen tablets, prescribing information (DailyMed) — Boxed warning; warnings: heart failure and edema

Answer: C. Opioid overdose signs include being unable to awaken or unresponsive, slow or shallow breathing (sometimes with gurgling or snoring sounds), bluish lips or fingernails, and very small (pinpoint) pupils in a person who is hard to wake.

Why the other choices are wrong:

• A. Agitation and dilated pupils suggest a stimulant, not an opioid.
• B. This pattern does not fit opioid toxicity.
• D. Mild drowsiness with normal responsiveness is not an overdose picture.

Remember: Opioid overdose: can't wake, can't breathe well, tiny pupils.

Source: SAMHSA Opioid Overdose Prevention Toolkit: five essential steps for first responders — Recognizing overdose; response steps; naloxone limits; Mayo Clinic, Naloxone (nasal route) — Description (OTC status; signs of opioid emergency)

Answer: B. Levothyroxine labeling states that the diagnosis of hypothyroidism is confirmed by measuring TSH with a sensitive assay together with free T4. Ongoing therapy is then judged by periodic lab tests and clinical evaluation.

Why the other choices are wrong:

• A. These evaluate glucose control, not thyroid function.
• C. These evaluate calcium status.
• D. These are coagulation tests.

Remember: Hypothyroidism is confirmed with TSH plus free T4.

Source: Levothyroxine sodium tablets, USP, prescribing information (DailyMed) — Dosage and administration; laboratory tests; drug interactions

Answer: A. Metformin labeling calls for an eGFR at least annually in all patients, with more frequent assessment in those at risk for renal impairment, such as older adults. Kidney function determines whether metformin can be started or continued.

Why the other choices are wrong:

• B. Metformin is substantially excreted by the kidney, so monitoring matters.
• C. Waiting for symptoms is not the labeled approach.
• D. Weekly 24-hour collections are not required.

Remember: Metformin: eGFR at baseline and at least yearly.

Source: Metformin hydrochloride tablets, prescribing information (DailyMed) — Dosage and administration; contraindications; iodinated contrast

Answer: A, B, C. Warfarin labeling advises more frequent INR monitoring when starting or stopping other drugs, including botanicals, or when changing doses of other drugs, specifically including short-term drugs such as antibiotics, antifungals, and corticosteroids.

Why the other choices are wrong:

• D. Blood type is not a factor in warfarin response described in the label.

Remember: An unexpected INR means a medication history, including herbals and short courses.

Source: Warfarin sodium tablets, prescribing information (DailyMed) — Drug interactions (CYP450); dosing by indication; INR monitoring

Answer: 41 mL/min. CrCl = [(140 − age) × weight × 0.85 for females] ÷ (72 × serum creatinine). (140 − 70) × 60 = 4,200. 72 × 1.2 = 86.4. 4,200 ÷ 86.4 = 48.6. 48.6 × 0.85 = 41.3, which rounds to 41 mL/min.

Common wrong answers:

• 49: This leaves out the 0.85 factor for women.
• 35: This applies 0.85 twice or uses the wrong denominator.

Remember: Cockcroft-Gault: (140 − age) × weight ÷ (72 × SCr), × 0.85 if female.

Source: StatPearls, Creatinine Clearance (PubMed record) — Cockcroft-Gault formula; Castleport worked calculation (inputs stated in the question)

Answer: C. 134 − (98 + 12) = 24. Using this formula, a normal anion gap is about 12 (with some variation by laboratory), so 24 is elevated. With a low bicarbonate, this suggests a high anion gap metabolic acidosis, such as diabetic ketoacidosis.

Why the other choices are wrong:

• A. This subtracts incorrectly.
• B. 12 is the approximate normal value, not this patient's result.
• D. The gap can be calculated from the three values given.

Remember: Anion gap = Na − (Cl + HCO3); about 12 is normal.

Source: Diagnosis and treatment of DKA and HHS (PMC) — Anion gap formula and normal value; StatPearls, Biochemistry, Anion Gap — HAGMA and DKA

Answer: A. 3.8 is above the labeled range of 2.0 to 3.0 for this valve type and position. An INR above range raises bleeding risk and calls for review of recent medication, diet, and dosing changes with the prescriber.

Why the other choices are wrong:

• B. 3.8 exceeds the upper limit of 3.0.
• C. 3.8 is higher than the range, not lower.
• D. The INR is interpreted against its target range; a platelet count is a separate test.

Remember: Know the target range before judging the INR.

Source: Warfarin sodium tablets, prescribing information (DailyMed) — Drug interactions (CYP450); dosing by indication; INR monitoring

Answer: D. Metformin labeling says to stop the drug at the time of, or before, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m², then re-evaluate eGFR 48 hours after the procedure and restart if renal function is stable. Contrast can acutely reduce kidney function and has been associated with lactic acidosis.

Why the other choices are wrong:

• A. This eGFR falls in the range where the label calls for a hold.
• B. There is no basis for increasing the dose.
• C. The hold is temporary if kidney function stays stable.

Remember: Metformin, eGFR 30–60, and IV contrast: hold, recheck at 48 hours, restart if stable.

Source: Metformin hydrochloride tablets, prescribing information (DailyMed) — Dosage and administration; contraindications; iodinated contrast

Answer: C. Lisinopril labeling lists renal insufficiency, diabetes, and concomitant potassium-sparing diuretics as risk factors for hyperkalemia, which can cause serious, sometimes fatal, arrhythmias. It advises using such combinations cautiously, if at all, with frequent potassium monitoring.

Why the other choices are wrong:

• A. A potassium of 6.0 mEq/L is elevated.
• B. Spironolactone is potassium-sparing; it raises potassium.
• D. ACE inhibitors raise potassium; they do not cause hypokalemia.

Remember: ACE inhibitor + potassium-sparing diuretic + CKD or diabetes = watch potassium closely.

Source: Lisinopril tablets, prescribing information (DailyMed) — Precautions: hyperkalemia; cough

Answer: C. Lisinopril labeling instructs patients to report immediately any signs of angioedema, such as swelling of the face, lips, tongue, or difficulty swallowing or breathing, and to take no more drug until they have consulted the prescriber. Swelling of the tongue or throat can be an emergency.

Why the other choices are wrong:

• A. More drug could worsen angioedema.
• B. Continuing the drug is not appropriate with suspected angioedema.
• D. Changing the timing does not address angioedema.

Remember: ACE inhibitor + facial or tongue swelling: stop and get help.

Source: Lisinopril tablets, prescribing information (DailyMed) — Highlights: warnings and drug interactions; patient counseling: angioedema

Answer: A, B, C. Alendronate labeling says to swallow the tablet whole with 6 to 8 ounces of plain water at least 30 minutes before the first food, drink, or medication of the day, and not to lie down for at least 30 minutes and until after the first food of the day. Staying upright lowers the risk of esophageal irritation.

Why the other choices are wrong:

• D. Coffee markedly reduces absorption; plain water only.

Remember: Alendronate: plain water, 30 minutes, stay upright.

Source: Alendronate sodium tablets, prescribing information (DailyMed) — Dosage and administration; patient counseling 17.2

Answer: D. The label directs 1 tablet under the tongue or in the buccal pouch at the first sign of an attack, allowed to dissolve without swallowing. One more tablet may be taken every 5 minutes, up to 3 tablets in 15 minutes. If pain persists after 3 tablets, or is different from usual, prompt medical attention is needed. Sitting down while taking it helps prevent falls from dizziness.

Why the other choices are wrong:

• A. Tablets are not swallowed, and 3 at once is not the labeled regimen.
• B. Hourly chewing is not the labeled regimen.
• C. Waiting 30 minutes delays care for possible acute coronary syndrome.

Remember: One, wait 5, repeat; after 3 in 15 minutes, get help.

Source: Nitroglycerin sublingual tablets, prescribing information (DailyMed) — Highlights: dosage and contraindications

Answer: B. Clopidogrel labeling advises avoiding concomitant omeprazole or esomeprazole. These CYP2C19 inhibitors can reduce formation of clopidogrel's active metabolite.

Why the other choices are wrong:

• A. Calcium carbonate is not named in the clopidogrel label as a CYP2C19 inhibitor to avoid.
• C. Famotidine is not the drug the label names to avoid.
• D. Alginate-antacid products are not named in the label as drugs to avoid.

Remember: Clopidogrel: steer clear of omeprazole and esomeprazole.

Source: Clopidogrel bisulfate tablets, prescribing information (DailyMed PDF) — Highlights: CYP2C19 inhibitors (omeprazole, esomeprazole)

Answer: B. Codeine-containing products are contraindicated in children younger than 12 years and in children younger than 18 following tonsillectomy and/or adenoidectomy. Life-threatening respiratory depression and death have occurred, many in children who were ultra-rapid CYP2D6 metabolizers.

Why the other choices are wrong:

• A. Dispensing a contraindicated drug is not appropriate.
• C. A lower dose does not remove the contraindication.
• D. Changing the timing does not remove the contraindication.

Remember: No codeine under 12, or under 18 after tonsillectomy.

Source: Codeine sulfate tablets, prescribing information (DailyMed) — Boxed warning; contraindications 4; warnings 5.6

Answer: D. Azathioprine labeling warns that TPMT or NUDT15 deficiency raises the risk of severe, life-threatening myelotoxicity with conventional doses, and advises considering alternative therapy in homozygous deficiency and reduced doses in heterozygous deficiency. Genetic testing does not replace CBC monitoring.

Why the other choices are wrong:

• A. Usual doses carry a high risk of severe myelotoxicity here.
• B. A higher dose would increase toxicity.
• C. The label applies TPMT and NUDT15 guidance to azathioprine directly.

Remember: Homozygous TPMT or NUDT15 deficiency: think alternative therapy.

Source: Azathioprine tablets, prescribing information (DailyMed) — Warnings: TPMT/NUDT15; precautions: drug interactions (xanthine oxidase inhibitors)

Answer: A. Metformin is contraindicated in patients with an eGFR below 30 mL/min/1.73 m². The label also says starting metformin is not recommended when eGFR is 30 to 45.

Why the other choices are wrong:

• B. An eGFR of 25 is below the contraindication threshold.
• C. A lower dose does not remove the contraindication.
• D. Taking it with meals does not change the renal contraindication.

Remember: Metformin: eGFR below 30 means do not use.

Source: Metformin hydrochloride tablets, prescribing information (DailyMed) — Dosage and administration; contraindications; iodinated contrast

Answer: A, B, C. Levothyroxine labeling calls for a single daily dose on an empty stomach, one-half to one hour before breakfast, taken with a full glass of water, and at least 4 hours apart from drugs that interfere with absorption, such as iron and calcium supplements and antacids.

Why the other choices are wrong:

• D. Calcium reduces levothyroxine absorption; they should be separated.

Remember: Levothyroxine: empty stomach, water, and space it from calcium and iron.

Source: Levothyroxine sodium tablets, prescribing information (DailyMed) — Dosage and administration 2.1; patient counseling; Levothyroxine sodium tablets, USP, prescribing information (DailyMed) — Dosage and administration; laboratory tests; drug interactions

Answer: B. Warfarin labeling advises more frequent INR monitoring when starting or stopping other drugs, including short-term drugs such as antifungals. Fluconazole inhibits CYP2C9 and can raise the INR.

Why the other choices are wrong:

• A. This interaction calls for closer monitoring.
• C. Waiting until the end misses the rise during treatment.
• D. Platelet counts do not measure warfarin effect.

Remember: New interacting drug on warfarin: check the INR more often.

Source: Warfarin sodium tablets, prescribing information (DailyMed) — Drug interactions (CYP450); dosing by indication; INR monitoring

Answer: B. The linezolid label says that when a patient already on a serotonergic antidepressant needs urgent linezolid and alternatives are not available, the antidepressant should be stopped promptly and linezolid given, with monitoring for signs and symptoms of serotonin syndrome or NMS-like reactions.

Why the other choices are wrong:

• A. Combining them without precautions risks serotonin syndrome.
• C. Raising the serotonergic dose increases risk.
• D. Delaying urgent antibiotic therapy is not the labeled approach when linezolid is needed urgently.

Remember: Urgent linezolid on an SSRI: stop the SSRI and watch closely.

Source: Linezolid injection, prescribing information (DailyMed) — Warnings: serotonin syndrome; clinical pharmacology: MAO inhibition

Answer: A, B, C. SAMHSA's toolkit describes calling 911, giving naloxone, and supporting breathing (rescue breathing) when a person is not breathing. Naloxone reverses opioid effects.

Why the other choices are wrong:

• D. SAMHSA notes naloxone has no effect on non-opioid overdoses, such as those involving only benzodiazepines, cocaine, or alcohol.

Remember: Call, give naloxone, breathe for them. Naloxone treats opioids only.

Source: SAMHSA Opioid Overdose Prevention Toolkit: five essential steps for first responders — Recognizing overdose; response steps; naloxone limits

Answer: B. Codeine labeling reports at least one death in a nursing infant exposed to high levels of morphine in breast milk because the mother was an ultra-rapid metabolizer of codeine. The same genetic variability that endangers children applies to breastfed infants through the mother.

Why the other choices are wrong:

• A. Codeine is not labeled for effects on milk supply.
• C. This is not the concern described.
• D. The labeled concern is morphine reaching the infant through milk.

Remember: Codeine and breastfeeding: think about the mother's CYP2D6 status and the baby's breathing.

Source: Acetaminophen and codeine tablets, prescribing information (DailyMed) — Warnings: ultra-rapid metabolism; nursing infant

Answer: A. Acetylcysteine labeling states that it reduces the extent of liver injury after acetaminophen overdose and is most effective when given early. Waiting for signs of liver damage wastes the window when it helps most.

Why the other choices are wrong:

• B. Delay reduces its benefit.
• C. It limits injury; it is not described as reversing established necrosis.
• D. It is indicated for acetaminophen overdose, including acute ingestion.

Remember: Acetylcysteine: earlier is better.

Source: Acetylcysteine injection, prescribing information (DailyMed) — Clinical pharmacology: acetaminophen overdose; acetylcysteine treatment; Antidote for acetaminophen poisoning: N-acetylcysteine (review) — Abstract

Answer: C. Carbamazepine labeling says to discontinue it at the first sign of a rash unless the rash is clearly not drug-related, and not to resume it if signs suggest SJS/TEN. The label also notes most carbamazepine-related SJS/TEN occurs within the first few months.

Why the other choices are wrong:

• A. Continuing risks progression to a serious skin reaction.
• B. Raising the dose is inappropriate.
• D. A new rash on carbamazepine needs prompt evaluation.

Remember: New rash early on carbamazepine: stop unless clearly unrelated.

Source: Carbamazepine tablets, prescribing information (DailyMed) — Boxed warning; warnings: SJS/TEN and HLA-B*1502

Answer: A, B, C. MMR, varicella, and yellow fever vaccines are live attenuated vaccines, along with live attenuated influenza vaccine. Knowing which vaccines are live matters for pregnancy, immunosuppression, and spacing rules.

Why the other choices are wrong:

• D. Td contains toxoids, not live organisms.

Remember: Live list to know: MMR, varicella, yellow fever, live attenuated influenza.

Source: Immunize.org, Ask the Experts: contraindications and precautions — Live attenuated vaccines; methotrexate and high-level immunosuppression

Answer: D. CDC's general best practices state that two or more injectable or nasally administered live vaccines not given on the same day should be separated by at least 4 weeks. Giving them too close together can reduce the response to the second vaccine.

Why the other choices are wrong:

• A. One day is well short of the 4-week minimum.
• B. The interval is 4 weeks, not a year.
• C. They can be given on the same day, or separated by at least 4 weeks.

Remember: Live injectables: same day or 4 weeks apart.

Source: CDC, Timing and Spacing of Immunobiologics (General Best Practices) — Nonsimultaneous live vaccines

Answer: B. CDC states that varicella vaccine is contraindicated during pregnancy because the effects of the vaccine virus on the fetus are unknown. Nonpregnant women who are vaccinated should avoid becoming pregnant for 1 month after each injection.

Why the other choices are wrong:

• A. Live varicella vaccine is contraindicated during pregnancy.
• C. Partial doses do not change the contraindication.
• D. The contraindication applies throughout pregnancy.

Remember: Varicella vaccine: not during pregnancy; avoid pregnancy for 1 month after.

Source: CDC, Guidelines for Vaccinating Pregnant Women — Varicella vaccine

Answer: A. CDC advises washing hands with soap and water every time after using the bathroom and before eating, and asking caregivers to do the same. CDC calls soap-and-water handwashing the best way to prevent person-to-person spread.

Why the other choices are wrong:

• B. Alcohol-based hand sanitizer does not kill C. difficile spores.
• C. Handwashing is the key preventive step.
• D. Antibiotic exposure is not a prevention strategy here.

Remember: C. diff at home: soap and water, every time.

Source: CDC, Preventing C. diff — Healthcare precautions; handwashing

Answer: A. For creatinine clearance of at least 10 and no more than 30 mL/min, the label says to halve the usual initial dose. For a clearance below 10 mL/min or hemodialysis, it recommends an initial dose of 2.5 mg.

Why the other choices are wrong:

• B. The label reduces the starting dose in this range.
• C. Reduced clearance never calls for a higher starting dose.
• D. The label adjusts the dose rather than contraindicating it.

Remember: Lisinopril, CrCl 10–30: halve the starting dose.

Source: Qbrelis (lisinopril) oral solution, prescribing information (DailyMed) — Highlights: dosage in renal impairment

Answer: B. Clopidogrel labeling gives these prevalence figures: about 2% of White and 4% of Black patients, and higher in Asian patients, such as 14% of Chinese patients. It also notes that tests to identify poor metabolizers are available.

Why the other choices are wrong:

• A. Prevalence differs by population.
• C. Poor metabolizers form less active metabolite.
• D. The label states tests are available.

Remember: CYP2C19 poor-metabolizer status varies by ancestry, and tests exist.

Source: Clopidogrel tablets, prescribing information (DailyMed) — Boxed warning; clinical pharmacology 12.5 (pharmacogenomics)

Answer: B. The Orange Book explains that for levothyroxine, therapeutic equivalence has been established between products with the same AB-number code, and some products carry more than one code. Three-character codes are generally used when there is more than one reference listed drug under the same heading.

Why the other choices are wrong:

• A. An AB1 product is equivalent to AB1 products, not automatically to AB2.
• C. The Orange Book states an AB1 or AB2 rating does not imply product preference.
• D. Codes beginning with A indicate therapeutic equivalence.

Remember: With AB numbers, match the number.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: D. The Orange Book states that different topical dosage forms, such as creams and ointments, are not considered pharmaceutically equivalent even with the same active ingredient and potency, and therefore are not considered therapeutically equivalent.

Why the other choices are wrong:

• A. Different dosage forms are not pharmaceutical equivalents.
• B. AB ratings apply within pharmaceutical equivalents.
• C. Matching strength does not make different dosage forms equivalent.

Remember: Cream is not ointment, even at the same strength.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: C. The Orange Book explains that extended-release products may differ in bioavailability because manufacturers rarely use the same formulation approach. Extended-release products without submitted bioequivalence data are coded BC; those with such data are coded AB.

Why the other choices are wrong:

• A. Demonstrated bioequivalence would lead to an AB code.
• B. The code describes equivalence status, not brand status.
• D. The code says nothing about the age group.

Remember: BC = extended-release without bioequivalence data.

Source: FDA, Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book), 46th ed., 2026 — Preface sections 1.2, 1.5, 1.7, 1.8

Answer: D. NCCIH explains that St. John's wort can decrease the effects of drugs by speeding up the processes that turn them into inactive substances, and it lists birth control pills among the medicines affected. The patient should talk with her prescriber about her mood and about contraception.

Why the other choices are wrong:

• A. It reduces, rather than increases, the effect.
• B. NCCIH describes this interaction specifically.
• C. NCCIH lists several classes of drugs it affects.

Remember: St. John's wort speeds drug breakdown; birth control can fail.

Source: NCCIH, Some supplements may decrease the effects of medications — St. John's wort

Answer: A. Naloxone nasal spray is available over the counter in the United States, as well as by prescription. It is used for emergency treatment of a known or suspected opioid overdose, and 911 should still be called.

Why the other choices are wrong:

• B. OTC naloxone nasal spray is available.
• C. Laypeople can give it.
• D. It is sold in community settings.

Remember: Naloxone nasal spray is OTC. Still call 911.

Source: FDA, Prescription to Nonprescription Switch List — naloxone nasal spray OTC approvals; SAMHSA Opioid Overdose Prevention Toolkit: five essential steps for first responders — recognizing overdose and response steps