Pharmacy Pharmacokinetics 3

Question 1

Which CYP450 enzyme is responsible for metabolizing the largest proportion of clinically used drugs?

Accepted Answer

CYP3A4

Answer

CYP1A2

Answer

CYP2D6

Answer

CYP2C9

Question 2

Co-administration of a potent CYP3A4 inhibitor with a CYP3A4 substrate drug would be expected to:

Accepted Answer

Increase plasma concentrations of the substrate, raising toxicity risk

Answer

Increase metabolism of the substrate, lowering plasma levels

Answer

Decrease plasma concentrations and reduce drug effect

Answer

Have no clinically significant effect on substrate levels

Question 3

Which of the following is a classic example of a prodrug that requires CYP2C19-mediated hepatic activation for antiplatelet effect?

Accepted Answer

Clopidogrel

Answer

Aspirin

Answer

Warfarin

Answer

Atorvastatin

Question 4

In elderly patients, which pharmacokinetic change most commonly leads to drug accumulation and toxicity with renally eliminated drugs?

Accepted Answer

Decreased renal clearance (reduced GFR)

Answer

Increased volume of distribution for hydrophilic drugs

Answer

Increased plasma protein binding with age

Answer

Increased hepatic first-pass metabolism

Question 5

Therapeutic drug monitoring (TDM) of aminoglycosides typically involves measuring which levels?

Accepted Answer

Peak and trough serum concentrations

Answer

Area under the curve (AUC) only

Answer

Trough levels only to ensure efficacy

Answer

Peak levels only to prevent nephrotoxicity

Question 6

Which of the following drugs is most appropriate for therapeutic drug monitoring due to its narrow therapeutic index?

Accepted Answer

Digoxin

Answer

Acetaminophen at standard doses

Answer

Ibuprofen

Answer

Omeprazole

Question 7

Enterohepatic recirculation of a drug can result in:

Accepted Answer

Extended drug half-life by returning drug from bile back to systemic circulation

Answer

Decreased bioavailability due to repeated hepatic exposure

Answer

Increased renal clearance through enhanced tubular secretion

Answer

Decreased volume of distribution due to bile storage