Which medication is a Proton Pump Inhibitor?

• A. Cimetidine
• B. Esomeprazole
• C. Sucralfate
• D. Ranitidine

Answer: (B)

Proton Pump Inhibitors block the final step in acid production by irreversibly inhibiting the H+/K+ ATPase pump on gastric parietal cells, giving strong and long-lasting suppression of stomach acid. Esomeprazole is a PPI and, as a prodrug, is activated in the acidic environment of the parietal cell and then covalently binds the proton pump, shutting down its activity until new pumps are made. That prolonged action is why PPIs are favored for conditions like GERD, ulcers, and H. pylori therapy.

The other drugs don’t fit this mechanism. Cimetidine and ranitidine are H2 receptor antagonists; they reduce acid by blocking histamine’s effect on parietal cells, not by inhibiting the proton pump. Sucralfate protects the mucosa by forming a barrier rather than decreasing acid secretion.