Repeated USMLE Questions Step 1 Review | 138

Q- A 60-year-old patient with chronic heart failure is started on digoxin. Which electrolyte imbalance increases the risk of digoxin toxicity?

A- Hyperkalemia

B- Hypocalcemia

C- Hypokalemia

D- Hyponatremia

C- Hypokalemia- Low potassium enhances digoxin binding to the Na⁺/K⁺-ATPase, increasing the risk of toxicity (arrhythmias, visual disturbances).

Q- Which of the following drugs inhibits bacterial folate synthesis by blocking dihydropteroate synthase?

A- Ciprofloxacin

B- Isoniazid

C- Trimethoprim

D- Sulfamethoxazole

D- Sulfamethoxazole- Sulfonamides inhibit dihydropteroate synthesis. Trimethoprim inhibits dihydrofolate reductase.

Q- A patient with asthma develops tremor and tachycardia after using his inhaler. Which of the following drugs is most likely responsible?

A- Albuterol

B- Ipratropium

C- Beclomethasone

D- Montelukast

A- Albuterol- Albuterol is a short-acting β₂-agonist that can cause tremor and tachycardia due to some β₁ stimulation.

Dr Ray Makar

Repeated USMLE Questions Step 1 Review- 138- Pharmacology