Hypochlorhydria may be promoted by which class of drugs?

• A. NSAIDs
• B. H2 receptor antagonists
• C. Proton pump inhibitors and antacids
• D. Antibiotics

Answer: (C)

The concept being tested is how certain medications lower stomach acidity to create hypochlorhydria. Proton pump inhibitors and antacids do this through two complementary mechanisms.

Proton pump inhibitors block the final step of acid production by inhibiting the H+/K+ ATPase “proton pump” on the stomach’s parietal cells. With the pump inhibited, less hydrogen ion (acid) is secreted into the stomach, so the environment becomes less acidic and the pH rises.

Antacids, on the other hand, neutralize existing gastric acid directly. By raising the pH quickly, they reduce acidity in the stomach immediately, contributing to a hypochlorhydric state.

Together, these two classes directly reduce gastric acidity—either by suppressing production or by neutralizing what’s there. The other options don’t consistently produce hypochlorhydria in the same direct way: NSAIDs mainly irritate the stomach lining, antibiotics don’t typically alter acid levels, and while H2 blockers also lower acid, the listed combination specifically highlights the two most direct routes to higher gastric pH.