FPGEE Pharmacology 4 — Questions and Answers
Question 1: A drug with a narrow therapeutic index requires careful monitoring. Which of the following is the best example of a narrow therapeutic index drug?
- Digoxin (Correct answer)
- Amoxicillin
- Ibuprofen
- Atorvastatin
Correct answer: Digoxin
Digoxin has a narrow therapeutic range (0.5–2 ng/mL); toxicity manifests with cardiac arrhythmias and visual disturbances at slightly suprathe rapeutic levels.
Question 2: Which drug class is the mechanism of clopidogrel's antiplatelet effect?
- Irreversible P2Y12 ADP receptor antagonist (Correct answer)
- Reversible COX-1 inhibitor
- Phosphodiesterase inhibitor
- GPIIb/IIIa receptor antagonist
Correct answer: Irreversible P2Y12 ADP receptor antagonist
Clopidogrel is a prodrug converted to an active metabolite that irreversibly binds and blocks the P2Y12 ADP receptor on platelets.
Question 3: What is the mechanism of action of aminoglycosides?
- Bind the 30S ribosomal subunit, causing misreading of mRNA (Correct answer)
- Bind the 50S subunit to inhibit peptide bond formation
- Inhibit bacterial RNA polymerase
- Block cell wall transpeptidation
Correct answer: Bind the 30S ribosomal subunit, causing misreading of mRNA
Aminoglycosides bind the 16S rRNA of the 30S subunit, causing codon misreading and premature termination of protein synthesis.
Question 4: Which phase II metabolic reaction involves conjugation with glucuronic acid?
- Glucuronidation (Correct answer)
- Sulfation
- Acetylation
- Methylation
Correct answer: Glucuronidation
Glucuronidation, catalyzed by UDP-glucuronosyltransferases (UGTs), conjugates glucuronic acid to drugs to increase water solubility for excretion.
Question 5: A patient on lithium is started on a thiazide diuretic. What is the expected outcome?
- Lithium toxicity due to increased renal reabsorption (Correct answer)
- Reduced lithium levels due to enhanced renal excretion
- No interaction because lithium is not metabolized
- Lithium toxicity due to hepatic enzyme inhibition
Correct answer: Lithium toxicity due to increased renal reabsorption
Thiazides cause sodium depletion, prompting the kidney to reabsorb more sodium and lithium together in the proximal tubule, increasing lithium levels.
Question 6: Which immunosuppressant acts by inhibiting calcineurin, thereby blocking IL-2 transcription?
- Cyclosporine (Correct answer)
- Azathioprine
- Sirolimus
- Mycophenolate mofetil
Correct answer: Cyclosporine
Cyclosporine binds cyclophilin to form a complex that inhibits calcineurin, preventing NFAT dephosphorylation and IL-2 gene transcription.
Question 7: A patient develops 'red man syndrome' during vancomycin infusion. What is the recommended management?
- Slow the infusion rate and pretreat with antihistamines (Correct answer)
- Discontinue vancomycin permanently and switch antibiotics
- Administer epinephrine immediately for anaphylaxis
- Increase the dose to overcome the reaction
Correct answer: Slow the infusion rate and pretreat with antihistamines
Red man syndrome is a rate-related infusion reaction; slowing the infusion and premedication with diphenhydramine prevents and manages this non-immune reaction.
FPGEE Pharmacology 4
A drug with a narrow therapeutic index requires careful monitoring.
Which of the following is the best example of a narrow therapeutic index drug?