Bismuth an old drug with new therapeutic implications.

For the last three centuries, Bismuth compounds have been of traditional importance for the treatment of infectious diseases, syphilis, amoebiasis, dyspepsia and diarrhea 1. Despite its old history, intensive research and investigation on the mechanism of action and its clinical efficacy has begun in recent years.Trivalent bismuth preparations such as bismuth subsalicylate (BSS) and colloidal bismuth subcitrate (CBS) are of most therapeutic efficacy amongst the available compounds. Indications for bismuth therapy in clinical practice are manifold. The fact that ulcer can develop with even normal acid secretion, prompted reexamination of ulcer therapy and renewed interest to try agents such as bismuth, that heal ulcers without reducing acid. Therapeutic efficacy of bismuth preparations are due to their cytoprotective and demulcent action 1. It coats the gastroduodenal mucosa especially ulcerated part and protects it against the digestive activity of acid and pepsin 2. It also increases prostaglandin synthesis which in turn increases mucous and bicarbonate secretion and reduces the H+ ion back diffusion 3,4. Various studies have demonstrated the efficacy of bismuth compound in the healing of duodenal ulcer, 82% with CBS as compared to 43% with placebo at 4 weeks 5 , three other studies compared CBS with ranitidine, showing 84% vs 78% healing rates respectively 6. Trials to see the efficacy of bismuth when combined with H2 receptor antagonists are very few, with inconclusive results 8. In gastric ulcer the results of bismuth therapy are similar to those of duodenal ulcer, being 72% as compared to 36% with placebo at 4 weeks and 96% with bismuth at 8 weeks 8. At present high relapse rates with various potent antiulcer drugs is the main problem to be solved especially after withdrawal of the treatment. Promising results have been reported for bismuth in duodenal as well as though less convincing in gastric ulcer 6. In a comparative study relapse rates at 4, 8 and 12 months were 41%, 55% and 62% respectively, as compared to 74%, 85% and 89% with ranitidine 9. Although these studies suggest superiority of bismuth in ulcer healing and reducing relapse rate, additional strategies are needed. Recent rediscovery of helicobacter pylori (HP) occupies a central place in the pathogenesis of ulcer disease. HP was found to be associated in upto 75% of gastric and over 90% of duodenal ulcer patients 10,11. Bismuth is active against HP and it also inhibits the proteolytic enzyme activity elaborated by this organism. …