NAPLEX QBANK Pharmacology and Drug Mechanisms 2 — Questions and Answers
Question 1: Which mechanism explains the antiplatelet effect of clopidogrel?
- Irreversible P2Y12 ADP receptor blockade (Correct answer)
- COX-1 acetylation
- GP IIb/IIIa receptor antagonism
- Phosphodiesterase-3 inhibition
Correct answer: Irreversible P2Y12 ADP receptor blockade
Clopidogrel's active metabolite irreversibly inhibits the platelet P2Y12 ADP receptor.
Question 2: A patient on warfarin starts amiodarone; what is the expected interaction?
- Increased INR from CYP2C9/CYP3A4 inhibition (Correct answer)
- Decreased INR from enzyme induction
- No interaction
- Decreased warfarin absorption
Correct answer: Increased INR from CYP2C9/CYP3A4 inhibition
Amiodarone inhibits CYP2C9 and CYP3A4, raising warfarin levels and INR.
Question 3: Which diuretic acts on the Na-K-2Cl cotransporter in the thick ascending limb?
- Furosemide (Correct answer)
- Hydrochlorothiazide
- Spironolactone
- Acetazolamide
Correct answer: Furosemide
Loop diuretics like furosemide inhibit the Na-K-2Cl cotransporter.
Question 4: The mechanism of metformin's glucose-lowering effect primarily involves:
- AMPK activation and decreased hepatic gluconeogenesis (Correct answer)
- Stimulation of insulin secretion
- Inhibition of intestinal alpha-glucosidase
- SGLT2 inhibition in the proximal tubule
Correct answer: AMPK activation and decreased hepatic gluconeogenesis
Metformin activates AMPK and reduces hepatic glucose production.
Question 5: Which receptor does ondansetron antagonize to prevent nausea?
- 5-HT3 serotonin receptor (Correct answer)
- D2 dopamine receptor
- H1 histamine receptor
- NK1 substance P receptor
Correct answer: 5-HT3 serotonin receptor
Ondansetron blocks 5-HT3 receptors centrally and in the GI tract.
Question 6: What best describes the action of sacubitril in sacubitril/valsartan?
- Neprilysin inhibition increasing natriuretic peptides (Correct answer)
- ACE inhibition
- Beta-1 receptor blockade
- Aldosterone receptor antagonism
Correct answer: Neprilysin inhibition increasing natriuretic peptides
Sacubitril inhibits neprilysin, raising beneficial natriuretic peptide levels.
Question 7: Which agent is a selective beta-2 agonist used for acute bronchospasm?
- Albuterol (Correct answer)
- Metoprolol
- Atenolol
- Carvedilol
Correct answer: Albuterol
Albuterol is a short-acting beta-2 agonist that relaxes bronchial smooth muscle.
NAPLEX QBANK Pharmacology and Drug Mechanisms 2
Which mechanism explains the antiplatelet effect of clopidogrel?