Pharmacological Studies of Sodium Alginate. I. Protective Effect of Sodium Alginate on Mucous Membranes of Upper-Gastrointestinal Tract
The pharmacological actions of sodium alginate on the mucosa of the upper gastrointestinal tract were studied by in vivo and in vitro experiments. To induce the experimental gastric erosion, rats were administered orally with 500 mg/kg of aspirin, and subsequently treated with oral administration of 5% (w/v) solution of sodium alginate. Histopathological observation of the stomach of these rats showed that sodium alginate formed a thick layer and covered the foci of aspirin-induced erosion. It was suggested that the layer of sodium alginate restrained the destruction of tissues and hemorrhage at the foci of erosion. The digestion of the mucosa of the excised rat stomach or rabbit esophagus in artificial gastric juice was highly inhibited when the mucosa was previously treated with 5% solution of sodium alginate. This was evidenced by the fact that significantly fewer amount of tyrosine was separated into the incubation medium from the alginate-treated stomach or esophagus as compared with untreated controls. Sodium alginate showed only weak antacid or no anti-pepsin actions. Accordingly, it was suggested that the layer of sodium alginate covering the lesion may inhibit the lytic action of pepsin and hydrochloric acid, and may protect the mucosal surface of the stomach and esophagus mainly by its mechanical action.