, Question 1
A patient with chronic kidney disease (CrCl 25 mL/min) is prescribed a drug
that is 90% renally eliminated and has a narrow therapeutic index. Which
pharmacokinetic parameter is most critical to monitor to avoid toxicity?
A. Volume of distribution (Vd)
B. Half-life (t1/2)
C. Bioavailability (F)
D. Protein binding
Correct Answer: B - Half-life (t1/2)
RATIONALE
In renal impairment, reduced clearance prolongs half-life, increasing
risk of toxicity for narrow therapeutic index drugs. Vd, bioavailability,
and protein binding are less directly affected by renal function, though
protein binding may change in uremia.
Question 2
A patient with major depressive disorder and CYP2D6 poor metabolizer status
is started on fluoxetine. Which adjustment is most appropriate?
A. Increase the dose to achieve therapeutic effect
B. Switch to a non-CYP2D6 substrate antidepressant
C. Monitor for serotonin syndrome and consider dose reduction
D. No adjustment needed; fluoxetine is a prodrug
Correct Answer: C - Monitor for serotonin syndrome and
consider dose reduction
RATIONALE
CYP2D6 poor metabolizers have reduced clearance of fluoxetine,
leading to higher plasma levels and increased risk of adverse effects,
including serotonin syndrome. Dose reduction or alternative therapy is
warranted; fluoxetine is not a prodrug.
Page 2
, Question 3
Which of the following best explains why a beta-blocker is effective in
reducing mortality in heart failure with reduced ejection fraction (HFrEF)?
A. Increased myocardial contractility
B. Reduction in heart rate and sympathetic tone
C. Direct vasodilation of coronary arteries
D. Inhibition of the renin-angiotensin-aldosterone system
Correct Answer: B - Reduction in heart rate and sympathetic
tone
RATIONALE
Beta-blockers improve outcomes in HFrEF by reducing heart rate,
myocardial oxygen demand, and sympathetic nervous system
overactivity, which reverse adverse remodeling. They do not increase
contractility or directly dilate coronary arteries.
Question 4
A patient on warfarin is prescribed trimethoprim-sulfamethoxazole for a
urinary tract infection. Which intervention is most critical?
A. Increase warfarin dose to maintain INR
B. Monitor INR closely and adjust warfarin dose as needed
C. Switch to a different antibiotic to avoid interaction
D. No action needed; interaction is minimal
Correct Answer: B - Monitor INR closely and adjust warfarin
dose as needed
RATIONALE
Trimethoprim-sulfamethoxazole inhibits CYP2C9, increasing
warfarin's anticoagulant effect and bleeding risk. Close INR
monitoring and dose adjustment are essential; switching antibiotics
may be considered but monitoring is paramount.
Page 3
, Question 5
A patient with asthma is prescribed a long-acting beta-agonist (LABA) without
an inhaled corticosteroid. What is the primary concern?
A. Increased risk of asthma-related death
B. Development of tolerance to LABA
C. Rebound bronchoconstriction
D. Increased risk of oral thrush
Correct Answer: A - Increased risk of asthma-related death
RATIONALE
LABAs used without inhaled corticosteroids are associated with an
increased risk of severe asthma exacerbations and asthma-related
death. Current guidelines mandate combination therapy with an
inhaled corticosteroid.
Question 6
Which statement accurately describes the mechanism of action of SGLT2
inhibitors in heart failure?
A. They increase renal sodium and water excretion, reducing preload.
B. They directly inhibit myocardial sodium channels.
C. They block aldosterone receptors, reducing afterload.
D. They increase myocardial contractility.
Correct Answer: A - They increase renal sodium and water
excretion, reducing preload.
RATIONALE
SGLT2 inhibitors promote natriuresis and glucosuria, leading to
reduced preload and improved cardiac function. They do not directly
affect myocardial sodium channels or aldosterone receptors.
Page 4
A patient with chronic kidney disease (CrCl 25 mL/min) is prescribed a drug
that is 90% renally eliminated and has a narrow therapeutic index. Which
pharmacokinetic parameter is most critical to monitor to avoid toxicity?
A. Volume of distribution (Vd)
B. Half-life (t1/2)
C. Bioavailability (F)
D. Protein binding
Correct Answer: B - Half-life (t1/2)
RATIONALE
In renal impairment, reduced clearance prolongs half-life, increasing
risk of toxicity for narrow therapeutic index drugs. Vd, bioavailability,
and protein binding are less directly affected by renal function, though
protein binding may change in uremia.
Question 2
A patient with major depressive disorder and CYP2D6 poor metabolizer status
is started on fluoxetine. Which adjustment is most appropriate?
A. Increase the dose to achieve therapeutic effect
B. Switch to a non-CYP2D6 substrate antidepressant
C. Monitor for serotonin syndrome and consider dose reduction
D. No adjustment needed; fluoxetine is a prodrug
Correct Answer: C - Monitor for serotonin syndrome and
consider dose reduction
RATIONALE
CYP2D6 poor metabolizers have reduced clearance of fluoxetine,
leading to higher plasma levels and increased risk of adverse effects,
including serotonin syndrome. Dose reduction or alternative therapy is
warranted; fluoxetine is not a prodrug.
Page 2
, Question 3
Which of the following best explains why a beta-blocker is effective in
reducing mortality in heart failure with reduced ejection fraction (HFrEF)?
A. Increased myocardial contractility
B. Reduction in heart rate and sympathetic tone
C. Direct vasodilation of coronary arteries
D. Inhibition of the renin-angiotensin-aldosterone system
Correct Answer: B - Reduction in heart rate and sympathetic
tone
RATIONALE
Beta-blockers improve outcomes in HFrEF by reducing heart rate,
myocardial oxygen demand, and sympathetic nervous system
overactivity, which reverse adverse remodeling. They do not increase
contractility or directly dilate coronary arteries.
Question 4
A patient on warfarin is prescribed trimethoprim-sulfamethoxazole for a
urinary tract infection. Which intervention is most critical?
A. Increase warfarin dose to maintain INR
B. Monitor INR closely and adjust warfarin dose as needed
C. Switch to a different antibiotic to avoid interaction
D. No action needed; interaction is minimal
Correct Answer: B - Monitor INR closely and adjust warfarin
dose as needed
RATIONALE
Trimethoprim-sulfamethoxazole inhibits CYP2C9, increasing
warfarin's anticoagulant effect and bleeding risk. Close INR
monitoring and dose adjustment are essential; switching antibiotics
may be considered but monitoring is paramount.
Page 3
, Question 5
A patient with asthma is prescribed a long-acting beta-agonist (LABA) without
an inhaled corticosteroid. What is the primary concern?
A. Increased risk of asthma-related death
B. Development of tolerance to LABA
C. Rebound bronchoconstriction
D. Increased risk of oral thrush
Correct Answer: A - Increased risk of asthma-related death
RATIONALE
LABAs used without inhaled corticosteroids are associated with an
increased risk of severe asthma exacerbations and asthma-related
death. Current guidelines mandate combination therapy with an
inhaled corticosteroid.
Question 6
Which statement accurately describes the mechanism of action of SGLT2
inhibitors in heart failure?
A. They increase renal sodium and water excretion, reducing preload.
B. They directly inhibit myocardial sodium channels.
C. They block aldosterone receptors, reducing afterload.
D. They increase myocardial contractility.
Correct Answer: A - They increase renal sodium and water
excretion, reducing preload.
RATIONALE
SGLT2 inhibitors promote natriuresis and glucosuria, leading to
reduced preload and improved cardiac function. They do not directly
affect myocardial sodium channels or aldosterone receptors.
Page 4
