Mechanism of Action of Antacids in GERD
Antacids treat gastroesophageal reflux disease by increasing gastric pH (Answer B) through direct buffering of gastric acid in the esophagus and stomach, which reduces heartburn and allows mucosal healing of esophagitis 1.
How Antacids Work
Antacids are a class of medications that directly neutralize gastric acid rather than suppressing acid production 1. This mechanism differs fundamentally from other GERD medications:
- Antacids buffer existing acid to raise pH above the damaging threshold 1, 2
- They provide rapid but temporary symptom relief, with an ultrashort duration of buffering action 3
- The neutralization effect occurs both in the stomach and esophagus where refluxed acid causes symptoms 1
Clinical Role in GERD Management
Antacids are primarily used for on-demand relief of mild, intermittent symptoms rather than as primary therapy for moderate-to-severe GERD 1:
- They rapidly relieve heartburn in patients with persistent or mild reflux symptoms 4
- Alginate-antacid combinations are superior to both placebo and antacids alone for treating mild reflux symptoms 4
- Alginates are particularly useful for neutralizing the postprandial acid pocket and may benefit patients with post-prandial/nighttime symptoms or hiatal hernia 1
Why Other Answer Choices Are Incorrect
Antacids do NOT increase lower esophageal sphincter tone (Answer A is wrong) - this mechanism belongs to prokinetic agents and baclofen, which reduce transient lower esophageal sphincter relaxations 2, 3.
Antacids do NOT decrease gastric pH (Answer C is wrong) - this would worsen GERD by making gastric contents more acidic 1.
Antacids do NOT primarily work by increasing serum calcium (Answer D is wrong) - while some antacids contain calcium, this is not their therapeutic mechanism for GERD 1.
Important Clinical Caveats
- Antacids can interfere with absorption of other medications and should be avoided with certain drugs like baloxavir marboxil 5
- Treatment trials have demonstrated unexpectedly prolonged maintenance of high esophageal pH with both tablet and liquid antacid formulations 6
- There are no well-designed placebo-controlled trials demonstrating esophageal mucosal healing with antacids alone 6
- For patients requiring chronic acid suppression (Los Angeles B or greater esophagitis, Barrett's esophagus, peptic stricture), antacids are insufficient and PPI therapy is required 1