Three high-yield USMLE Step 1 pharmacology questions on classic drug side effects and drug choice: aspirin toxicity, drug-induced hypokalemia and the treatment of bulimia nervosa. Pick your answer first, then open the explanation.
Question 1: Which symptom is a sign of aspirin toxicity?
Which of the following symptoms is known to be related to aspirin toxicity?
A. Diarrhea B. Dry cough C. Headache D. Tinnitus
Correct answer: D. Tinnitus
Tinnitus (ringing in the ears) is an early, classic sign of salicylate toxicity. It is dose-related and usually reversible, but very high levels can cause hearing loss.
Why the other options are wrong:
Diarrhea is not typical; aspirin toxicity more often causes nausea and vomiting.
Dry cough is the classic side effect of ACE inhibitors, not aspirin.
Headache is non-specific and not a characteristic sign of salicylate toxicity.
High-yield: Aspirin overdose causes a mixed acid–base disorder: early respiratory alkalosis (direct stimulation of the respiratory center), then an anion gap metabolic acidosis. Treat with sodium bicarbonate to alkalinize the urine; dialysis in severe cases.
Question 2: Which drug causes hypokalemia?
Which one of the following drugs most likely contributes to hypokalemia?
A. Cyclosporine B. Furosemide C. Propranolol D. Tacrolimus
Correct answer: B. Furosemide
Furosemide is a loop diuretic that blocks the Na-K-2Cl cotransporter in the thick ascending limb of the loop of Henle. The increased sodium delivery to the collecting duct increases potassium secretion, causing hypokalemia and metabolic alkalosis.
Why the other options are wrong:
Cyclosporine and tacrolimus (calcineurin inhibitors) cause hyperkalemia, as well as nephrotoxicity.
Propranolol (beta-blocker) shifts potassium out of cells and tends to raise serum potassium.
Question 3: Which antidepressant is used to treat bulimia nervosa?
Which of the following antidepressants is the most effective against bulimia nervosa?
A. Amitriptyline B. Fluoxetine C. Imipramine D. Paroxetine
Correct answer: B. Fluoxetine
Fluoxetine (an SSRI) is the only FDA-approved medication for bulimia nervosa, used together with cognitive behavioral therapy. It is also used for depression, obsessive-compulsive disorder, panic disorder and premenstrual dysphoric disorder.
Why the other options are wrong:
Amitriptyline and imipramine are tricyclic antidepressants with anticholinergic and cardiac side effects; they are not first-line for bulimia.
Paroxetine is an SSRI, but fluoxetine is the one approved and best studied for bulimia.
High-yield:Bupropion is contraindicated in bulimia and anorexia nervosa because it lowers the seizure threshold, especially with electrolyte disturbances.
Key takeaways
Aspirin toxicity → tinnitus; respiratory alkalosis then anion gap metabolic acidosis.
