Repeated USMLE Questions Step 1 Review- 142- Pharmacology

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Q- A 55-year-old man with atrial fibrillation is taking warfarin. He is started on trimethoprim-sulfamethoxazole for a urinary tract infection. What is the most likely outcome of this drug interaction?

A- Decreased anticoagulant effect

B- Enhanced metabolism of warfarin

C- Increased risk of bleeding

D- No significant effect

C- Increased risk of bleeding- Sulfonamides inhibit warfarin metabolism (CYP2C9 inhibition), leading to higher plasma levels and increased bleeding risk.

 

Q- A 35-year-old woman with generalized anxiety disorder is started on buspirone. Which of the following statements about this drug is correct?

A- It acts as a partial agonist at 5-HT₁A receptors

B- It causes dependence and withdrawal effects

C- It has sedative and muscle relaxant properties

D- It provides rapid relief of anxiety symptoms

A- It acts as a partial agonist at 5-HT₁A receptors- Buspirone is a non-benzodiazepine anxiolytic that works as a 5-HT₁A partial agonist. It has no sedation or dependence, but takes 1–2 weeks for effect.

 

Q- Which of the following drugs is most likely to cause ototoxicity and nephrotoxicity, especially when combined with loop diuretics?

A- Amoxicillin

B- Azithromycin

C- Ceftriaxone

D- Gentamicin

D- Gentamicin- Aminoglycosides (like gentamicin) can cause dose-dependent nephrotoxicity and irreversible ototoxicity, especially when combined with furosemide.

 

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Dr Ray Makar
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