**Question:** Acid reflux is prevented by all except:

A. Proton pump inhibitors (PPIs)
B. Antacids
C. H2-receptor antagonists
D. Alginates

**Core Concept:** Acid reflux is the backward flow of stomach acid into the esophagus, which can cause symptoms like heartburn and damage to the esophageal mucosa. Treatment options aim to reduce gastric acid secretion or neutralize the acid.

**Why the Correct Answer is Right:** Acid reflux prevention is typically achieved by either decreasing gastric acid secretion or neutralizing the acid. Proton pump inhibitors (PPIs) are potent inhibitors of stomach acid production, while antacids neutralize the stomach acid, making them effective in preventing acid reflux. Alginates form a protective barrier over the stomach lining, also preventing acid reflux.

**Why Each Wrong Option is Incorrect:** Alginates (option D) are not directly involved in reducing gastric acid secretion but rather form a gel-like barrier over the stomach lining, protecting it from the acid. H2-receptor antagonists (option B) reduce gastric acid secretion by blocking histamine receptors, but they are less potent than PPIs. PPIs (option A) are stronger inhibitors of gastric acid secretion, making them more effective in preventing acid reflux compared to H2-receptor antagonists.

**Clinical Pearl:** In patients with acid reflux symptoms, a combination therapy of PPIs and antacids may be prescribed for optimal acid reflux prevention, as both medications work together to neutralize and decrease acid production.

**Correct Answer:** D. Alginates