A 55-year-old man with a history of peptic ulcer disease requires long-term anti-inflammatory therapy for rheumatoid arthritis. His physician prescribes celecoxib and adds misoprostol. What is the mechanism by which misoprostol protects the gastric mucosa in this setting?

• A Neutralizes gastric acid by acting as a base
• B Forms a protective coating over the ulcer base
• C Blocks histamine H2 receptors on parietal cells, reducing acid secretion
• D Acts as a PGE1 analog, stimulating mucus and bicarbonate secretion and maintaining mucosal blood flow via EP3/EP4 receptors ✓

Explanation

Misoprostol is a synthetic PGE1 analog that activates EP3 and EP4 prostaglandin receptors on gastric epithelial cells, stimulating mucus and bicarbonate secretion and maintaining mucosal blood flow. It replaces the protective prostaglandins whose synthesis is inhibited by NSAIDs. It is specifically indicated for NSAID-induced gastric ulcer prophylaxis in high-risk patients. Its main side effect is dose-related diarrhea.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.