Bismuth subsalicylate

The exact mechanism of bismuth subsalicylate is not fully understood. Bismuth subsalicylate is an insoluble complex that constitutes salicylic acid and trivalent bismuth. Once orally administered, bismuth subsalicylate hydrolyzes in the stomach into bismuth oxychloride, which is minimally absorbed into the bloodstream, and salicylic acid, which is almost completely absorbed. Bismuth interacts with other anions and compounds, such as hydrochloric acid, bicarbonate, phosphate, and hydrogen sulfide, in the gastrointestinal tract to form bismuth salts such as bismuth oxychloride, bismuth subcarbonate, bismuth phosphate, and bismuth sulfide. Bismuth salts possess bactericidal and antimicrobial activity, mainly by preventing bacteria from binding and growing on the mucosal cells of the stomach. It has no effects on normal gut flora. By preventing bacteria from binding to mucosal cells, bismuth subsalicylate prevents intestinal secretion and fluid loss, promotes fluid and electrolyte reabsorption, reduces gastrointestinal inflammation, and promotes the healing of pre-existing ulcer in the stomach. Salicylic acid from dissociated bismuth subsalicylate adds to the anti-inflammatory actions of bismuth salts by inhibiting the cyclooxygenase enzyme and limiting the formation of prostaglandin, a pro-inflammatory mediator. Bismuth subsalicylate exhibits cytoprotective and demulcent activity, which makes it an effective drug in peptic ulcer disease. It blocks the adhesion of H. pylori to the gastric epithelial cells and blocks the bacteria's enzyme activities, including phospholipase, protease, and urease.