250 Questions with Verified Answers & Rationales | 2026/2027 Latest
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Questions 1–250
Domain 1: Pharmacokinetics & Pharmacodynamics (Questions 1–20)
1. A patient with hepatic cirrhosis has reduced phase I metabolism.
Which drug would be most affected?
A) Lorazepam (phase II glucuronidation)
B) Phenytoin (phase I oxidation)
C) Digoxin (renal excretion)
D) Acetaminophen (phase II conjugation)
Answer B: Phenytoin (phase I oxidation)
,Rationale: Phase I reactions (oxidation, reduction, hydrolysis) are
more affected by cirrhosis than phase II conjugation.
2. A patient with a genetic polymorphism resulting in CYP2D6 poor
metabolizer phenotype is prescribed codeine. What is the most
likely outcome?
A) Increased risk of respiratory depression
B) Little to no analgesic effect
C) Prolonged half-life of codeine
D) Increased risk of serotonin syndrome
Answer B: Little to no analgesic effect
Rationale: CYP2D6 is required to convert codeine to its active
metabolite morphine; poor metabolizers have reduced analgesia.
3. A patient is prescribed a drug that is 98% protein-bound. Which
condition would increase the risk of toxicity?
A) Obesity
B) Hypoalbuminemia (low albumin)
C) Renal failure
,D) Hepatic cirrhosis
Answer B: Hypoalbuminemia (low albumin)
Rationale: Low albumin increases the free fraction of highly protein-
bound drugs, increasing effect and toxicity risk.
4. A patient is receiving a drug that is a P-glycoprotein (P-gp)
substrate. Which co-administered drug would increase its oral
bioavailability?
A) Rifampin (P-gp inducer)
B) Ketoconazole (P-gp inhibitor)
C) Phenytoin (P-gp inducer)
D) St. John's wort (P-gp inducer)
Answer B: Ketoconazole (P-gp inhibitor)
Rationale: P-gp inhibitors decrease drug efflux from intestinal cells,
increasing absorption and oral bioavailability.
5. What is the therapeutic index of a drug?
A) The dose that produces a therapeutic effect
B) The ratio of the toxic dose to the therapeutic dose
, C) The time required for the drug to reach steady state
D) The volume of distribution
Answer B: The ratio of the toxic dose to the therapeutic dose
Rationale: A narrow therapeutic index indicates a small margin
between therapeutic and toxic doses, requiring monitoring.
6. A patient is receiving a drug with a high first-pass effect. Which
route of administration would bypass this?
A) Oral
B) Sublingual or IV
C) Rectal
D) Topical
Answer B: Sublingual or IV
Rationale: Sublingual and IV routes bypass first-pass metabolism in
the liver.
7. The half-life of a drug is 4 hours. Approximately how long will it
take to reach steady state?
A) 8 hours