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Pharmacology · single question

Omeprazole reduces gastric acid by which mechanism?

  1. Irreversibly inhibits the H+/K+-ATPase (proton pump) of gastric parietal cells
  2. Blocks histamine H2 receptors
  3. Neutralizes acid as a base
  4. Coats the gastric mucosa
Show answer and explanation

Correct answer: A. Irreversibly inhibits the H+/K+-ATPase (proton pump) of gastric parietal cells

  • A. Correct. Omeprazole is a proton-pump inhibitor that irreversibly blocks the parietal-cell H+/K+-ATPase, the final step of acid secretion.
  • B. H2 blockers (e.g., ranitidine) act on histamine receptors—a different class.
  • C. Antacids neutralize acid; PPIs inhibit its production.
  • D. Sucralfate coats the mucosa; that is not the PPI mechanism.

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