Explain the mechanism by which omeprazole promotes healing of peptic ulcers and state why it is preferred over H2‑receptor antagonists for long‑term therapy.
Answer
Omeprazole irreversibly inhibits the H⁺/K⁺‑ATPase pump in gastric parietal cells, leading to profound and sustained reduction of gastric acid secretion; it is preferred for long‑term use because it provides longer duration of acid suppression, higher potency, and better ulcer‑healing rates than H2‑blockers, which show tolerance with chronic use.
Step-by-step solution
- Describe the target of omeprazole – the H⁺/K⁺‑ATPase (proton pump) on the secretory surface of parietal cells.
- Explain that omeprazole is a pro‑drug activated in the acidic canaliculi, forming a covalent disulfide bond that irreversibly blocks the pump.
- State that irreversible inhibition leads to a prolonged fall in gastric H⁺ secretion until new pumps are synthesised (about 18‑24 h).
- Contrast this with H2‑receptor antagonists, which competitively block histamine receptors and can develop tachyphylaxis with continuous use.
- Conclude that the stronger, longer‑lasting acid suppression by omeprazole creates a favourable environment for ulcer healing and reduces recurrence, making it the drug of choice for chronic therapy.
Common mistake: Confusing reversible H2‑blockade with irreversible proton‑pump inhibition
Concept tested: Proton pump inhibitor action in ulcer healing
Published · How this solution was prepared and checked
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