Pharmacology · single question
What is the mechanism of action of omeprazole?
Show answer and explanation
Correct answer: A. Proton pump inhibitor
Omeprazole irreversibly blocks the H+/K+ ATPase ('proton pump') in gastric parietal cells, which is the final common step of acid secretion — making it a proton pump inhibitor (PPI), distinct from H2-receptor antagonists (like famotidine) or other classes.
- A. ✅ CORRECT – Omeprazole is a PPI; irreversibly inhibits the gastric proton pump.
- B. ❌ Prostaglandin analogs (misoprostol) protect gastric mucosa; not PPIs.
- C. ❌ Antacids neutralize existing acid; omeprazole prevents its production.
- D. ❌ H2 receptor antagonists (ranitidine) block histamine receptors; omeprazole works at the pump.