, Question 1
Which pharmacokinetic parameter is most directly altered by the addition of a
potent CYP3A4 inhibitor to a regimen of a drug that is a high-extraction
CYP3A4 substrate given orally?
A. Volume of distribution
B. Oral bioavailability
C. Renal clearance
D. Protein binding
Correct Answer: B - Oral bioavailability
RATIONALE
For a high-extraction oral substrate, extensive first-pass CYP3A4
metabolism limits bioavailability; inhibiting CYP3A4 reduces
first-pass extraction and markedly increases oral bioavailability.
Volume of distribution, renal clearance, and protein binding are not
primarily determined by CYP3A4 activity.
Question 2
A patient with heart failure with reduced ejection fraction is started on
sacubitril/valsartan. Which monitoring parameter best reflects the
pharmacodynamic effect and safety of this combination?
A. Serum potassium and creatinine
B. INR
C. Fasting glucose
D. Serum amylase
Correct Answer: A - Serum potassium and creatinine
Page 2
, RATIONALE
Sacubitril/valsartan provides neprilysin inhibition and angiotensin
receptor blockade, increasing natriuresis but also risk of hyperkalemia
and renal impairment, so potassium and creatinine are key. INR,
glucose, and amylase are not the primary safety parameters for this
agent.
Question 3
Which statement best explains why clopidogrel's antiplatelet effect is
diminished in a patient with a loss-of-function CYP2C19 allele?
A. Clopidogrel is excreted unchanged and CYP2C19 affects renal
elimination.
B. Clopidogrel requires CYP2C19-mediated bioactivation to its active
thiol metabolite.
C. CYP2C19 inhibition increases clopidogrel's active metabolite
clearance.
D. Loss-of-function CYP2C19 increases platelet P2Y12 receptor
sensitivity.
Correct Answer: B - Clopidogrel requires CYP2C19-mediated
bioactivation to its active thiol metabolite.
RATIONALE
Clopidogrel is a prodrug that must be converted by CYP2C19 to its
active metabolite to irreversibly inhibit P2Y12; reduced CYP2C19
activity lowers active metabolite formation and antiplatelet response.
The other options misstate the metabolic pathway or mechanism.
Question 4
A patient on warfarin is prescribed trimethoprim-sulfamethoxazole for a
urinary tract infection. Which combination of mechanisms best explains the
resulting INR elevation?
A. CYP2C9 inhibition plus displacement from albumin
Page 3
, B. CYP2C9 induction plus increased vitamin K intake
C. Renal tubular secretion inhibition plus platelet activation
D. Gut flora alteration plus CYP3A4 induction
Correct Answer: A - CYP2C9 inhibition plus displacement from
albumin
RATIONALE
Trimethoprim-sulfamethoxazole inhibits CYP2C9 (reducing warfarin
metabolism) and can displace warfarin from albumin, both increasing
free warfarin and INR. The other options describe mechanisms that
would not produce this interaction profile.
Question 5
Which agent is most appropriate as first-line therapy for a patient with newly
diagnosed type 2 diabetes and a BMI of 34 kg/m² who has no
contraindications and prioritizes weight loss?
A. Glipizide
B. Pioglitazone
C. Semaglutide
D. Insulin glargine
Correct Answer: C - Semaglutide
RATIONALE
GLP-1 receptor agonists such as semaglutide promote weight loss and
are preferred when weight reduction is a priority, per current ADA
standards. Sulfonylureas, thiazolidinediones, and basal insulin are
associated with weight gain or neutral effects.
Question 6
Which monitoring strategy is essential when initiating an ACE inhibitor in a
patient with chronic kidney disease and baseline creatinine of 1.8 mg/dL?
A. Check serum potassium and creatinine within 1-2 weeks
Page 4
Which pharmacokinetic parameter is most directly altered by the addition of a
potent CYP3A4 inhibitor to a regimen of a drug that is a high-extraction
CYP3A4 substrate given orally?
A. Volume of distribution
B. Oral bioavailability
C. Renal clearance
D. Protein binding
Correct Answer: B - Oral bioavailability
RATIONALE
For a high-extraction oral substrate, extensive first-pass CYP3A4
metabolism limits bioavailability; inhibiting CYP3A4 reduces
first-pass extraction and markedly increases oral bioavailability.
Volume of distribution, renal clearance, and protein binding are not
primarily determined by CYP3A4 activity.
Question 2
A patient with heart failure with reduced ejection fraction is started on
sacubitril/valsartan. Which monitoring parameter best reflects the
pharmacodynamic effect and safety of this combination?
A. Serum potassium and creatinine
B. INR
C. Fasting glucose
D. Serum amylase
Correct Answer: A - Serum potassium and creatinine
Page 2
, RATIONALE
Sacubitril/valsartan provides neprilysin inhibition and angiotensin
receptor blockade, increasing natriuresis but also risk of hyperkalemia
and renal impairment, so potassium and creatinine are key. INR,
glucose, and amylase are not the primary safety parameters for this
agent.
Question 3
Which statement best explains why clopidogrel's antiplatelet effect is
diminished in a patient with a loss-of-function CYP2C19 allele?
A. Clopidogrel is excreted unchanged and CYP2C19 affects renal
elimination.
B. Clopidogrel requires CYP2C19-mediated bioactivation to its active
thiol metabolite.
C. CYP2C19 inhibition increases clopidogrel's active metabolite
clearance.
D. Loss-of-function CYP2C19 increases platelet P2Y12 receptor
sensitivity.
Correct Answer: B - Clopidogrel requires CYP2C19-mediated
bioactivation to its active thiol metabolite.
RATIONALE
Clopidogrel is a prodrug that must be converted by CYP2C19 to its
active metabolite to irreversibly inhibit P2Y12; reduced CYP2C19
activity lowers active metabolite formation and antiplatelet response.
The other options misstate the metabolic pathway or mechanism.
Question 4
A patient on warfarin is prescribed trimethoprim-sulfamethoxazole for a
urinary tract infection. Which combination of mechanisms best explains the
resulting INR elevation?
A. CYP2C9 inhibition plus displacement from albumin
Page 3
, B. CYP2C9 induction plus increased vitamin K intake
C. Renal tubular secretion inhibition plus platelet activation
D. Gut flora alteration plus CYP3A4 induction
Correct Answer: A - CYP2C9 inhibition plus displacement from
albumin
RATIONALE
Trimethoprim-sulfamethoxazole inhibits CYP2C9 (reducing warfarin
metabolism) and can displace warfarin from albumin, both increasing
free warfarin and INR. The other options describe mechanisms that
would not produce this interaction profile.
Question 5
Which agent is most appropriate as first-line therapy for a patient with newly
diagnosed type 2 diabetes and a BMI of 34 kg/m² who has no
contraindications and prioritizes weight loss?
A. Glipizide
B. Pioglitazone
C. Semaglutide
D. Insulin glargine
Correct Answer: C - Semaglutide
RATIONALE
GLP-1 receptor agonists such as semaglutide promote weight loss and
are preferred when weight reduction is a priority, per current ADA
standards. Sulfonylureas, thiazolidinediones, and basal insulin are
associated with weight gain or neutral effects.
Question 6
Which monitoring strategy is essential when initiating an ACE inhibitor in a
patient with chronic kidney disease and baseline creatinine of 1.8 mg/dL?
A. Check serum potassium and creatinine within 1-2 weeks
Page 4
