Putting a Cap on Acid Reflux
Researchers show that a polysaccharide ‘raft’ can float on top of acid in the stomach to block its backflow into the esophagus. It reduces reflux symptoms in patients with gastroesophageal reflux disease (GERD), according to a clinical trial the December issue of Clinical Gastroenterology and Hepatology.
GERD is a common condition in which backflow of stomach contents into the esophagus causes pain and often esophageal damage. Most of these acid reflux episodes occur after meals. This is because an unbuffered pool of acid floats on top of ingested food (the gastric acid pocket).
Wout O. Rohof et al. investigated whether alginates might be used to block this back-splashing of acid into the esophagus. Alginates are natural polysaccharide polymers that, on contact with gastric acid, quickly precipitate into a low-density viscous gel of near-neutral pH. The change in pH causes sodium bicarbonate in the formulation to release carbon dioxide, which floats to the top of the gastric contents like a raft—close to the esophagogastric junction, where the acid pocket forms (see video).
Rohof et al. studied the effects of a commercial alginate-antacid formulation (Gaviscon Double Action Liquid) in 16 patients with symptomatic GERD. They found that the alginate significantly reduced the number of acid reflux episodes (3.5 events), compared to patients given only an antacid after a meal (Antagel, 15 events). Furthermore, the time to acid reflux was significantly increased in patients receiving alginate-antacid (63 minutes) vs. those receiving antacid (14 minutes).
In imaging studies, the authors saw that the acid pocket was located below the diaphragm in 71% of patients given alginate-antacid vs. 21% of those given antacid. There was an inverse correlation between a sub-diaphragm position of the acid pocket and acid reflux.
Rohof et al. conclude that in patients with reflux after meals, the acid pocket can be directly targeted with a non-systemic, alginate-antacid formulation.
In an editorial that accompanies the article, Daniel Sifrim and Roberto Penagini write that the treatment is best-suited for patients with mild GERD symptoms, or possibly GERD symptoms during pregnancy. However, more data is needed to recommend alginates for patients with persistent symptoms in spite of PPI therapy.