A computerized artificial stomach model to assess sodium alginate-induced pH gradient

Abstract A computerized `artificial stomach' model capable 1) of measuring the pH both in gastric contents, using a combined glass electrode, and at its surface, using a surface microelectrode, 2) of simulating the gastric emptying regulation in regard to the intragastric pH in physiological situation and 3) of controlling the position of the surface microelectrode in regard to gastric volume variations by means of a surface detector system, has been used to analyze the antacid activity and the pH gradient induced by both alginate-containing drugs, different in their carbonate composition. When added to 0.1 N HCl solution, both drugs developed a floating `raft' at the surface supporting a pH gradient (close to 4 pH units) simultaneously with a moderate or weak antacid activity in gastric contents. Both studied drugs are capable of exerting a protective effect in gastro-esophageal reflux disease mainly by the induction of a pH gradient.