10 USMLE Pharmacology Quick Review Questions with Answers (Set 44)

These 10 quick USMLE pharmacology review questions test high-yield facts that show up again and again on the exam, including Ondansetron, Propranolol, Hydralazine, Omeprazole. Each question includes the correct answer.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A patient receiving chemotherapy develops severe nausea and vomiting. Which drug works by blocking serotonin (5-HT₃) receptors to control these symptoms?

A- Metoclopramide
B- Ondansetron
C- Promethazine
D- Scopolamine

B- Ondansetron- Ondansetron is a 5-HT₃ receptor antagonist commonly used for chemotherapy-induced nausea and vomiting.
The correct answer is B

 

Question 2. A drug selectively blocks voltage-gated sodium channels in rapidly firing neurons. Which property best explains its preferential effect?

A- Higher affinity for inactivated channels
B- Increased lipid solubility
C- Noncompetitive receptor binding
D- Rapid renal clearance

A- Higher affinity for inactivated channels- Use-dependent sodium channel blockers preferentially bind inactivated channels, making them more effective in rapidly firing neurons.
The correct answer is A

 

Question 3. A 34-year-old woman presents with heat intolerance, tremor, and palpitations. Labs show low TSH and elevated free T4. What is the most appropriate initial treatment?

A- Methimazole
B- Propranolol
C- Radioactive iodine
D- Thyroidectomy

B- Propranolol- Beta-blockers are used first to control adrenergic symptoms in hyperthyroidism before definitive therapy.
The correct answer is B

 

Question 4. A drug irreversibly inhibits an enzyme by forming a covalent bond at the active site. Which pharmacologic change will restore maximal enzyme activity?

A- Increasing substrate concentration
B- Increasing enzyme concentration
C- Decreasing competitive inhibitors
D- Removing allosteric modulators

B- Increasing enzyme concentration- Irreversible inhibitors permanently inactivate enzymes; only synthesis of new enzyme can restore maximal activity.
The correct answer is B

 

Question 5. A patient receiving amphotericin B develops fever, chills, and renal dysfunction. What is the primary mechanism of nephrotoxicity?

A- Afferent arteriole vasoconstriction
B- Autoimmune tubular injury
C- Direct glomerular inflammation
D- Inhibition of prostaglandin synthesis

A- Afferent arteriole vasoconstriction- Amphotericin B causes dose-dependent nephrotoxicity by constricting the afferent arteriole, reducing renal blood flow and GFR.
The correct answer is A

 

Question 6. A patient taking digoxin presents with nausea, confusion, and visual disturbances. Which electrolyte abnormality increases the risk of toxicity?

A- Hypercalcemia
B- Hyperkalemia
C- Hypocalcemia
D- Hypokalemia

D- Hypokalemia- Low potassium enhances digoxin binding to Na⁺/K⁺-ATPase, increasing the risk of arrhythmias and toxicity.
The correct answer is D

 

Question 7. Which medication is commonly associated with drug-induced lupus erythematosus?

A- Hydralazine
B- Methyldopa
C- Penicillamine
D- Propranolol

A- Hydralazine- Hydralazine can cause drug-induced lupus, especially in slow acetylators, presenting with arthralgia, fever, and positive ANA.
The correct answer is A

 

Question 8. A patient with peptic ulcer disease is prescribed misoprostol. What is the primary therapeutic effect of this drug?

A- Decreases gastric acid secretion
B- Increases gastric mucosal protection
C- Neutralizes gastric acid
D- Prevents Helicobacter pylori growth

B- Increases gastric mucosal protection- Misoprostol is a prostaglandin E1 analog. It protects the stomach lining by increasing mucus and bicarbonate secretion and mucosal blood flow (and it also modestly reduces acid secretion). It is mainly used to prevent NSAID-induced ulcers and is contraindicated in pregnancy because it causes uterine contractions.
The correct answer is B

 

Question 9. A patient on chronic steroid therapy abruptly stops the medication. Which complication is most likely?

A- Adrenal crisis
B- Cushing syndrome
C- Hyperaldosteronism
D- Thyroid storm

A- Adrenal crisis- Sudden withdrawal of long-term corticosteroids suppresses the HPA axis, leading to acute adrenal insufficiency.
The correct answer is A

 

Question 10. A patient with peptic ulcer disease is treated with a drug that irreversibly inhibits the H+/K+ ATPase. Which drug was given?

A- Cimetidine
B- Omeprazole
C- Ranitidine
D- Sucralfate

B- Omeprazole- PPIs (omeprazole) irreversibly block the gastric proton pump.
The correct answer is B

 

High-yield points from this set

  • Ondansetron is a 5-HT₃ receptor antagonist commonly used for chemotherapy-induced nausea and vomiting.
  • Use-dependent sodium channel blockers preferentially bind inactivated channels, making them more effective in rapidly firing neurons.
  • Beta-blockers are used first to control adrenergic symptoms in hyperthyroidism before definitive therapy.
  • Irreversible inhibitors permanently inactivate enzymes; only synthesis of new enzyme can restore maximal activity.
  • Amphotericin B causes dose-dependent nephrotoxicity by constricting the afferent arteriole, reducing renal blood flow and GFR.

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