Which statement correctly describes the mechanism of proton pump inhibitors?

Which statement correctly describes the mechanism of proton pump inhibitors?

• A. They inhibit the proton pump in gastric parietal cells.
• B. They block H2 receptors.
• C. They neutralize acid in the stomach lumen.
• D. They prevent acid secretion by blocking CFTR channels.

Answer: (A)

Proton pump inhibitors work by shutting down the final step of acid production in the stomach. They are prodrugs that become activated in the acidic environment of the parietal cell canaliculi and then irreversibly bind to the H+/K+-ATPase enzyme—the proton pump—on the luminal surface of gastric parietal cells. This blocks proton (H+) secretion into the stomach lumen, dramatically reducing gastric acidity. Because the pump is inactivated irreversibly, new proton pumps must be made to restore acid secretion, so the effect lasts well beyond the drug’s short plasma presence. This differs from blocking histamine H2 receptors (that would be H2 antagonists), neutralizing acid directly in the lumen (that’s what antacids do), or blocking CFTR chloride channels (not the mechanism by which gastric acid is secreted).

Proton pump inhibitors work by shutting down the final step of acid production in the stomach. They are prodrugs that become activated in the acidic environment of the parietal cell canaliculi and then irreversibly bind to the H+/K+-ATPase enzyme—the proton pump—on the luminal surface of gastric parietal cells. This blocks proton (H+) secretion into the stomach lumen, dramatically reducing gastric acidity. Because the pump is inactivated irreversibly, new proton pumps must be made to restore acid secretion, so the effect lasts well beyond the drug’s short plasma presence.

This differs from blocking histamine H2 receptors (that would be H2 antagonists), neutralizing acid directly in the lumen (that’s what antacids do), or blocking CFTR chloride channels (not the mechanism by which gastric acid is secreted).