Pharmacology · single question
Ranitidine (Zantac) and famotidine (Pepcid) share the same mechanism of action. This is:
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Correct answer: D. H2 receptor antagonist (blocks histamine H2 receptors on parietal cells → reduces acid secretion)
- A. H1 receptor antagonists (antihistamines like diphenhydramine, cetirizine) block allergic responses — not acid secretion.
- B. Proton pump inhibitors (omeprazole, pantoprazole) block the H+/K+ ATPase pump directly — a different, more complete mechanism.
- C. Anticholinergics reduce acid secretion by blocking muscarinic receptors, but this is not the mechanism of H2 blockers.
- D. Correct. Both ranitidine and famotidine are H2 RECEPTOR ANTAGONISTS. They competitively block histamine H2 receptors on gastric parietal cells, reducing cAMP-mediated acid secretion. They are used for peptic ulcers, GERD, and gastritis.