Which drug class reduces acid production by blocking the proton pumps in parietal cells?

• A. Proton Pump Inhibitors
• B. H2-receptor blockers
• C. Antacids
• D. Antiemetic

Answer: (A)

The main idea here is that the final step of stomach acid secretion is carried out by proton pumps (H+/K+ ATPase) on the surface of parietal cells. The drug class that reduces acid production by blocking these pumps is proton pump inhibitors. They inactivate the proton pump irreversibly, so the cell can no longer secrete hydrogen ions into the stomach. Since new proton pumps must be synthesized to resume acid production, the acid suppression lasts longer than the presence of the drug in the blood, often requiring dosing before meals to align with when pumps are most active. Examples include omeprazole, esomeprazole, pantoprazole, and lansoprazole. This mechanism makes them particularly effective for conditions like GERD and peptic ulcers, where lowering acid production is key. In contrast, other classes work differently: H2-receptor blockers reduce acid by blocking histamine signals to parietal cells (reversible and typically less potent), antacids neutralize existing acid, and antiemetics address nausea rather than acid production.