Which of the following is a proton pump inhibitor?

• A. Ranitidine
• B. Omeprazole
• C. Sucralfate
• D. Misoprostol

Answer: (B)

Proton pump inhibitors block the final step of acid production in the stomach by inhibiting the H+/K+ ATPase pump on parietal cells, leading to powerful and prolonged suppression of gastric acid. Omeprazole is one of these drugs, so it directly targets that pump to reduce acid secretion, which is why it’s the correct choice for a proton pump inhibitor. The other options work differently: a histamine H2 blocker reduces acid by blocking histamine’s effect on parietal cells; a mucosal protectant forms a barrier to shield the lining; and a prostaglandin analog protects the mucosa and also decreases acid. In clinical use, PPIs like omeprazole are often given before meals for maximal effect, and they are usually enteric-coated to prevent premature dissolution. Long-term use has considerations such as infection risk and nutrient absorption issues, and some PPIs can interact with other drugs like clopidogrel.