Which of the following is a proton pump inhibitor used to treat heartburn?

• A. Omeprazole
• B. Aluminum hydroxide
• C. Ranitidine
• D. Sucralfate

Answer: (A)

Proton pump inhibitors block the final step of acid production in the stomach by irreversibly inhibiting the H+/K+-ATPase (the proton pump) in gastric parietal cells. Omeprazole is a proton pump inhibitor, so it substantially reduces gastric acid secretion and helps relieve heartburn. Because the pump inhibition is irreversible, acid suppression lasts beyond the drug’s presence in the bloodstream, and full relief often builds over a few days; it’s typically most effective when taken before meals to ensure the pump is active when acid is being produced.

Aluminum hydroxide, by contrast, is an antacid that neutralizes existing gastric acid for quick but temporary relief. Ranitidine is an H2 receptor antagonist that decreases acid production by blocking histamine signaling in parietal cells. Sucralfate coats and protects the mucosa rather than suppressing acid production. With these mechanisms in mind, omeprazole best fits the role of a proton pump inhibitor used to treat heartburn.