, Question 1
A patient with chronic kidney disease (eGFR 28 mL/min/1.73 m²) is
prescribed metformin. Which pathophysiological consequence most directly
increases the risk of lactic acidosis?
A. Impaired renal clearance of metformin leading to accumulation and
inhibition of mitochondrial complex I.
B. Reduced hepatic gluconeogenesis causing decreased lactate
metabolism.
C. Increased renal tubular reabsorption of metformin causing osmotic
diuresis.
D. Enhanced intestinal absorption of metformin due to uremic
enteropathy.
Correct Answer: A - Impaired renal clearance of metformin
leading to accumulation and inhibition of mitochondrial complex
I.
RATIONALE
In CKD, reduced renal clearance leads to metformin accumulation,
which inhibits mitochondrial complex I, shifting metabolism toward
anaerobic glycolysis and increasing lactate production. Hepatic
gluconeogenesis is not the primary mechanism, and renal tubular
reabsorption or enhanced absorption are not significant factors.
Question 2
Which statement best explains why a beta-blocker with intrinsic
sympathomimetic activity (ISA) may be preferred over a non-ISA beta-blocker
in a patient with asthma and mild hypertension?
A. ISA provides partial beta-2 agonism, reducing bronchoconstriction
while still lowering blood pressure.
B. ISA selectively blocks beta-1 receptors, avoiding beta-2 mediated
bronchospasm.
Page 2
, C. ISA increases heart rate, which counteracts asthma-related
bradycardia.
D. ISA enhances renin release, improving renal perfusion.
Correct Answer: A - ISA provides partial beta-2 agonism,
reducing bronchoconstriction while still lowering blood pressure.
RATIONALE
Beta-blockers with ISA have partial agonist activity at beta-2
receptors, which can mitigate bronchoconstriction while still
providing beta-1 blockade for hypertension. Non-ISA beta-blockers
can cause bronchospasm by blocking beta-2 receptors. The other
options misstate the mechanism or effects of ISA.
Question 3
A patient on warfarin is prescribed fluconazole. Which pharmacokinetic
interaction is most likely to increase bleeding risk?
A. Fluconazole inhibits CYP2C9, reducing warfarin metabolism.
B. Fluconazole induces CYP3A4, increasing warfarin clearance.
C. Fluconazole displaces warfarin from albumin, increasing free drug.
D. Fluconazole enhances renal excretion of warfarin.
Correct Answer: A - Fluconazole inhibits CYP2C9, reducing
warfarin metabolism.
RATIONALE
Fluconazole is a potent inhibitor of CYP2C9, which metabolizes
S-warfarin, leading to increased warfarin levels and bleeding risk.
Induction of CYP3A4 would decrease warfarin effect, displacement is
minor, and enhanced renal excretion is not a mechanism.
Question 4
Which pharmacogenomic variant most strongly predicts reduced analgesic
efficacy of codeine due to impaired conversion to morphine?
Page 3
, A. CYP2D6 poor metabolizer phenotype
B. CYP3A4 ultrarapid metabolizer phenotype
C. UGT2B7 rapid glucuronidation
D. OPRM1 A118G polymorphism
Correct Answer: A - CYP2D6 poor metabolizer phenotype
RATIONALE
Codeine is a prodrug converted to morphine primarily by CYP2D6.
Poor metabolizers have reduced conversion, leading to inadequate
analgesia. CYP3A4 ultrarapid metabolism shunts codeine to
norcodeine, but CYP2D6 is the key pathway. UGT2B7 affects
morphine glucuronidation, and OPRM1 affects receptor sensitivity,
but neither is the primary determinant of codeine activation.
Question 5
A patient with heart failure and reduced ejection fraction is started on
sacubitril/valsartan. Which mechanism contributes to its superiority over
enalapril?
A. Inhibition of neprilysin increases natriuretic peptides, promoting
vasodilation and diuresis.
B. Sacubitril blocks angiotensin II receptors more selectively than
enalapril.
C. Valsartan inhibits neprilysin, increasing bradykinin.
D. Sacubitril enhances ACE activity, reducing angiotensin II.
Correct Answer: A - Inhibition of neprilysin increases natriuretic
peptides, promoting vasodilation and diuresis.
RATIONALE
Sacubitril inhibits neprilysin, increasing natriuretic peptides, which
cause vasodilation, natriuresis, and diuresis. Valsartan provides
angiotensin receptor blockade. Enalapril is an ACE inhibitor. The
other options misattribute mechanisms.
Page 4
A patient with chronic kidney disease (eGFR 28 mL/min/1.73 m²) is
prescribed metformin. Which pathophysiological consequence most directly
increases the risk of lactic acidosis?
A. Impaired renal clearance of metformin leading to accumulation and
inhibition of mitochondrial complex I.
B. Reduced hepatic gluconeogenesis causing decreased lactate
metabolism.
C. Increased renal tubular reabsorption of metformin causing osmotic
diuresis.
D. Enhanced intestinal absorption of metformin due to uremic
enteropathy.
Correct Answer: A - Impaired renal clearance of metformin
leading to accumulation and inhibition of mitochondrial complex
I.
RATIONALE
In CKD, reduced renal clearance leads to metformin accumulation,
which inhibits mitochondrial complex I, shifting metabolism toward
anaerobic glycolysis and increasing lactate production. Hepatic
gluconeogenesis is not the primary mechanism, and renal tubular
reabsorption or enhanced absorption are not significant factors.
Question 2
Which statement best explains why a beta-blocker with intrinsic
sympathomimetic activity (ISA) may be preferred over a non-ISA beta-blocker
in a patient with asthma and mild hypertension?
A. ISA provides partial beta-2 agonism, reducing bronchoconstriction
while still lowering blood pressure.
B. ISA selectively blocks beta-1 receptors, avoiding beta-2 mediated
bronchospasm.
Page 2
, C. ISA increases heart rate, which counteracts asthma-related
bradycardia.
D. ISA enhances renin release, improving renal perfusion.
Correct Answer: A - ISA provides partial beta-2 agonism,
reducing bronchoconstriction while still lowering blood pressure.
RATIONALE
Beta-blockers with ISA have partial agonist activity at beta-2
receptors, which can mitigate bronchoconstriction while still
providing beta-1 blockade for hypertension. Non-ISA beta-blockers
can cause bronchospasm by blocking beta-2 receptors. The other
options misstate the mechanism or effects of ISA.
Question 3
A patient on warfarin is prescribed fluconazole. Which pharmacokinetic
interaction is most likely to increase bleeding risk?
A. Fluconazole inhibits CYP2C9, reducing warfarin metabolism.
B. Fluconazole induces CYP3A4, increasing warfarin clearance.
C. Fluconazole displaces warfarin from albumin, increasing free drug.
D. Fluconazole enhances renal excretion of warfarin.
Correct Answer: A - Fluconazole inhibits CYP2C9, reducing
warfarin metabolism.
RATIONALE
Fluconazole is a potent inhibitor of CYP2C9, which metabolizes
S-warfarin, leading to increased warfarin levels and bleeding risk.
Induction of CYP3A4 would decrease warfarin effect, displacement is
minor, and enhanced renal excretion is not a mechanism.
Question 4
Which pharmacogenomic variant most strongly predicts reduced analgesic
efficacy of codeine due to impaired conversion to morphine?
Page 3
, A. CYP2D6 poor metabolizer phenotype
B. CYP3A4 ultrarapid metabolizer phenotype
C. UGT2B7 rapid glucuronidation
D. OPRM1 A118G polymorphism
Correct Answer: A - CYP2D6 poor metabolizer phenotype
RATIONALE
Codeine is a prodrug converted to morphine primarily by CYP2D6.
Poor metabolizers have reduced conversion, leading to inadequate
analgesia. CYP3A4 ultrarapid metabolism shunts codeine to
norcodeine, but CYP2D6 is the key pathway. UGT2B7 affects
morphine glucuronidation, and OPRM1 affects receptor sensitivity,
but neither is the primary determinant of codeine activation.
Question 5
A patient with heart failure and reduced ejection fraction is started on
sacubitril/valsartan. Which mechanism contributes to its superiority over
enalapril?
A. Inhibition of neprilysin increases natriuretic peptides, promoting
vasodilation and diuresis.
B. Sacubitril blocks angiotensin II receptors more selectively than
enalapril.
C. Valsartan inhibits neprilysin, increasing bradykinin.
D. Sacubitril enhances ACE activity, reducing angiotensin II.
Correct Answer: A - Inhibition of neprilysin increases natriuretic
peptides, promoting vasodilation and diuresis.
RATIONALE
Sacubitril inhibits neprilysin, increasing natriuretic peptides, which
cause vasodilation, natriuresis, and diuresis. Valsartan provides
angiotensin receptor blockade. Enalapril is an ACE inhibitor. The
other options misattribute mechanisms.
Page 4
