12 USMLE Pharmacology Quick Review Questions with Answers (Set 11)

These 12 quick USMLE review questions test high-yield facts that show up again and again on the exam: second messengers, atropine, therapeutic dose, phenoxybenzamine, ergotamine, digoxin, ezetimibe, methylergonovine, montelukast, levodopa, benzodiazepines and metoclopramide. 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. Which of the following is the cellular mechanism of epinephrine?

A- Activation of adenylyl cyclase
B- Activation of acetylcholinesterase
C- Activation of phospholipase
D- Inhibition of adenylyl cyclase

A- Activation of adenylyl cyclase- Epinephrine activates α1-adrenoceptors to cause a release of intracellular stored Ca 2+ and β1- and β2-adrenoceptors to activate adenylyl cyclase.
The correct answer is A

 

Question 2. Dry or “sandy eyes” is seen after administration of large doses of which one of the following medications?

A- Atropine
B- Carbachol
C- Pilocarpine
D- Timolol

A- Atropine- Atropine blocks muscarinic receptors and reduces lacrimal gland secretion, leading to dry eyes or a “sandy eyes” sensation. Carbachol and pilocarpine increase tear production, and timolol does not cause significant dryness.
The correct answer is A

 

Question 3. Which of the following statements correctly describes the therapeutic dose of medication?

A- The amount of medication that produces the maximal rate of distribution
B- The amount of medication that produces minimal biological effect
C- The amount of medication that produces the highest plasma concentration of the drug
D- The amount of medication that produces the required effect in the majority of patients

D- The amount of medication that produces the required effect in the majority of patients- The therapeutic dose is defined as the dose that achieves the desired clinical effect in most patients. It is not related to maximal distribution, minimal effect, or highest plasma concentration
The correct answer is D

 

Question 4. Which of the following medications is considered irreversible alpha receptor antagonist?

A- Labetalol
B- Phenoxybenzamine
C- Prazosin
D- Tolazoline

B- Phenoxybenzamine- Phenoxybenzamine is an irreversible (noncompetitive) alpha-adrenergic antagonist, commonly used in pheochromocytoma. The others are reversible alpha blockers.
The correct answer is B

 

Question 5. Which of the following is a serious complication of ergotamine?

A- Depression
B- Headache
C- Hypotension
D- Prolonged vasospasm

D- Prolonged vasospasm- This is the most dangerous side effect that can lead to coronary vasoconstriction.
The correct answer is D

 

Question 6. Which of the following is the mechanism of action of digoxin to increase cardiac contractility?

A- Inhibition of K/Ca ATPase
B- Inhibition of Na/Ca ATPase
C- Inhibition of Na/K ATPase
D- Inhibition of phosphodiesterase

C- Inhibition of Na/K ATPase- Digoxin increases cardiac contractility by inhibiting the Na⁺/K⁺ ATPase, which raises intracellular sodium levels. This reduces the activity of the Na⁺/Ca²⁺ exchanger, causing calcium to accumulate in cardiac cells and increasing contractility.
The correct answer is C

 

Question 7. Which of the following medications acts to prevent cholesterol absorption at the small intestine brush border?

A- Cholestyramine
B- Colestipol
C- Ezetimibe
D- Gemfibrozil

C- Ezetimibe- Cholestyramine and colestipol prevents intestinal absorption of bile acids, while gemfibrozil upregulates LPL.
The correct answer is C

 

Question 8. Which of the following is the main mechanism of action of methylergonovine in treating postpartum hemorrhage?

A- Blocking sympathetic stimulation
B- Forceful contraction of myometrium
C- Instant blood coagulation
D- Strong vasoconstriction

B- Forceful contraction of myometrium- It is a strong vasoconstrictor but myometrial contraction is dominant
The correct answer is B

 

Question 9. Which of the following medications is most likely prescribed in cases of asthma associated with chronic environmental allergies?

A- Albuterol inhaler
B- Fluticasone nasal spray
C- Oral fexofenadine
D- Oral montelukast

D- Oral montelukast – This is the only drug that can be used in asthma and allergies. A- in asthma only and B and C in allergies only.
The correct answer is D

 

Question 10. Which of the following adverse effects of L-DOPA is most likely the reason to limit its use?

A- Depression
B- Dyskinesia
C- Nausea and occasional vomiting
D- Orthostatic hypotension

B- Dyskinesia- Other side effects are temporary and relieved in a short time
The correct answer is B

 

Question 11. Which of the following is a contraindication of the use of benzodiazepines in anxiety disorders?

A- Diabetes mellitus
B- Seizures
C- Sleep apnea
D- Smoking

C- Sleep apnea- It is dangerous to use in cases of sleep apnea but other conditions are not that risky.
The correct answer is C

 

Question 12. Which of the following is the mechanism of action of metoclopramide?

A- α-Adrenoceptor antagonist
B- Dopamine D2-receptor antagonist
C- Nicotinic receptor antagonist
D- Selective serotonin reuptake inhibitor (SSRI)

B- Dopamine D2-receptor antagonist
The correct answer is B

 

High-yield points from this set

  • Phenoxybenzamine is an irreversible alpha-blocker (used before pheochromocytoma surgery).
  • Ergotamine can cause prolonged vasospasm.
  • Digoxin inhibits the Na+/K+ ATPase.
  • Benzodiazepines are risky in sleep apnea.

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