Review article: alginate‐raft formulations in the treatment of heartburn and acid reflux

Abstract

Alginate-based raft-forming formulations have been marketed word-wide for over 30 years under various brand names, including Gaviscon. They are used for the symptomatic treatment of heartburn and oesophagitis, and appear to act by a unique mechanism which differs from that of traditional antacids. In the presence of gastric acid, alginates precipitate, forming a gel. Alginate-based raft-forming formulations usually contain sodium or potassium bicarbonate; in the presence of gastric acid, the bicarbonate is converted to carbon dioxide which becomes entrapped within the gel precipitate, converting it into a foam which floats on the surface of the gastric contents, much like a raft on water. Both in vitro and in vivo studies have demonstrated that alginate-based rafts can entrap carbon dioxide, as well as antacid components contained in some formulations, thus providing a relatively pH-neutral barrier. Several studies have demonstrated that the alginate raft can preferentially move into the oesophagus in place, or ahead, of acidic gastric contents during episodes of gastro-oesophageal reflux; some studies further suggest that the raft can act as a physical barrier to reduce reflux episodes. Although some alginate-based formulations also contain antacid components which can provide significant acid neutralization capacity, the efficacy of these formulations to reduce heartburn symptoms does not appear to be totally dependent on the neutralization of bulk gastric contents. The strength of the alginate raft is dependant on several factors, including the amount of carbon dioxide generated and entrapped in the raft, the molecular properties of the alginate, and the presence of aluminium or calcium in the antacid components of the formulation. Raft formation occurs rapidly, often within a few seconds of dosing; hence alginate-containing antacids are comparable to traditional antacids for speed of onset of relief. Since the raft can be retained in the stomach for several hours, alginate-based raft-forming formulations can additionally provide longer-lasting relief than that of traditional antacids. Indeed, clinical studies have shown Gaviscon is superior to placebo, and equal to or significantly better than traditional antacids for relieving heartburn symptoms. Alginate-based, raft-forming formulations have been used to treat reflux symptoms in infants and children, and in the management of heartburn and reflux during pregnancy. While Gaviscon is effective when used alone, it is compatible with, and does not interfere with the activity of antisecretory agents such as cimetidine. Even with the introduction of new antisecretory and promotility agents, alginate-rafting formulations will continue to have a role in the treatment of heartburn and reflux symptoms. Their unique non-systemic mechanism of action provides rapid and long-duration relief of heartburn and acid reflux symptoms.

The efficacy of sodium alginate (Gaviscon) for the treatment of gastro-oesophageal reflux in preterm infants

“…[7][8][9][10][11] These drugs act by a physical mechanism: in the presence of gastric acid, alginates precipitate to form a low-density but viscous gel whereas sodium bicarbonate contained in the formulation is converted to carbon dioxide, which is entrapped within the gel and contributes forming a foam, which floats as a raft on the surface of gastric content and can preferentially enter the oesophagus instead of gastric content during reflux episodes. 12 Previous studies performed in infants are few and have obtained controversial results; [7][8][9][10] furthermore, at present, there are no studies on the effect of alginate preparations in preterm newborns. The aim of our study was to evaluate the effect of sodium alginate on GER features (i.e.…”

Effect of an anti-reflux medical device in the control of deflation cough: A placebo-controlled comparative study with an antacid drug in chronic coughers

“…According to published guidelines [13], antacids or anti-reflux products are also widely employed in the control of GOR symptoms, including chronic chough. A possible drawback of antacid therapy is the need of frequents drug administration, since the duration of action of these compounds is generally short lasting [14]. On the other hand, the need of frequents administration is known to negatively impact on patient compliance to the therapy, especially when the liking of the compound is low.…”

Alginates in therapy for gastroesophageal reflux disease

“…Бикарбонат натрия, входящий в со-став препарата, в присутствии кислоты желудочного сока превра-щается в углекислый газ, который захватывается альгинатным гелем, придавая ему плавучесть. В результате альгинатный гель плавает как «плот» на поверхности желудочного содержимого в отличие от антацидов, которые погружаются в дистальную часть желудка [38].…”