11 USMLE Pharmacology Quick Review Questions with Answers (Set 23)

These 11 quick USMLE review questions test high-yield facts that show up again and again on the exam: C. difficile treatment, NNRTIs, beta-blockers, gastroparesis, half-life, vasoconstrictors, quinidine, synergism, methacholine challenge, drug absorption and phenytoin. 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 develops severe diarrhea after 2 weeks of treating pneumonia with broad-spectrum antibiotics. Which of the following is the first line of treatment for this condition?

A- Ampicillin
B- Ciprofloxacin
C- Methicillin
D- Vancomycin

D- Vancomycin- Severe diarrhea after broad-spectrum antibiotics is most likely Clostridioides difficile colitis. First-line treatment is ORAL vancomycin or fidaxomicin (oral metronidazole only for mild cases when these are unavailable). Stop the offending antibiotic if possible. Ciprofloxacin and other broad-spectrum antibiotics actually increase the risk of C. difficile.
The correct answer is D

 

Question 2. Which of the following anti-retroviral treatments is a non-competitive reverse transcriptase inhibitor?

A- Didanosine
B- Nevirapine
C- Saquinavir
D- Zidovudine

B- Nevirapine- The only one on the list that is NCRTI. A and D are nucleoside reverse transcriptase inhibitors and C is a protease inhibitor.
The correct answer is B

 

Question 3. Which of the following are the most likely effects of beta blockers on the end-diastolic volume (EDV) and the ejection time (ET)?

A- Both of them decrease
B- Both of them increase
C- EDV decreases and ET increases
D- EDV increases and ET decreases

B- Both of them increase- Beta blockers decrease heart rate which allows more time for diastolic filling leading to increased EDV and eventually ET increases.
The correct answer is B

 

Question 4. Which of the following is the first-line therapy for gastroparesis in patients with diabetes?

A- Metoclopramide
B- Omeprazole
C- Ondansetron
D- Cimetidine

A- Metoclopramide- B is the first line treatment for gastroesophageal reflux disease. C is for nausea and vomiting of chemotherapy and D is for gastric ulcer.
The correct answer is A

 

Question 5. If the half-life of a certain drug is 5 hours, how long will it take until the drug level reaches 25% of the initial dose?

A- 5 hours
B- 7.5 hours
C- 10 hours
D- 15 hours

C- 10 hours- One half-life = 50%- two half-lives = 25%- three half-lives = 12.5% and so on.
The correct answer is C

 

Question 6. Which of the following agents most likely causes vasoconstriction?

A- Bradykinin
B- Histamine
C- Nitric oxide
D- Norepinephrine

D- Norepinephrine- This is the only one on the list can cause vasoconstriction. The others cause vasodilation.
The correct answer is D

 

Question 7. Administration of which one of the following medications can lead to the development of hemolytic anemia?

A- Hydralazine
B- Propranolol
C- Quinidine
D- Verapamil

C- Quinidine- It is the only one on the list can cause hemolytic anemia through the formation of an immune complex and destruction of RBCs. Hydralazine may lead to lupus-like syndrome but not hemolytic anemia.
The correct answer is C

 

Question 8. The effect of two medications is greater than the sum of their individual effects explains which of the following drug interactions?

A- Additive
B- Permissive
C- Synergistic
D- Tachyphylaxis

C- Synergistic- Additive means that the effect of the two are equal to the sum of their effects. It is permissive when one medication is required for the full effect of the other one. Tachyphylaxis is the decrease of effect after initial or repeated administration.
The correct answer is C

 

Question 9. Which one of the following cholinomimetic agents is used in the challenge test for diagnosis of asthma?

A- Bethanechol
B- Carbachol
C- Methacholine
D- Pilocarpine

C- Methacholine- It stimulates muscarinic receptors in the airways when inhaled.
The correct answer is C

 

Question 10. Which one of the following is the main mechanism of absorption of most drugs in the gastrointestinal tract (GIT)?

A- Endocytosis and exocytosis
B- Facilitated transport
C- Passive diffusion
D- Pinocytosis

C- Passive diffusion- It is explained by Fick Law of Diffusion in which the molecules move from higher drug conc. to lower drug conc.
The correct answer is C

 

Question 11. Which one of the following agents prolongs the duration of nerve block when combined with a local anesthetic?

A- Atropine
B- Dobutamine
C- Epinephrine
D- Isoproterenol

C- Epinephrine- It leads to local vasoconstriction which prolongs the duration of infiltration of nerve block.
The correct answer is C

 

High-yield points from this set

  • C. difficile colitis: oral vancomycin or fidaxomicin.
  • Nevirapine is a non-nucleoside reverse transcriptase inhibitor.
  • Two half-lives reduce a drug to 25% of its starting level.
  • Methacholine challenge tests airway hyperreactivity in asthma.

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