Bismuth compounds have several effects that are beneficial for ulcer healing: anti-microbial activity against H. pylori(mechanism unknown), stimulation of prostaglandin synthesis thereby increasing mucosal protection, and chelation with exposed ulcer proteins and protecting the ulcer base.
When given as monotherapy, bismuth compounds are not very effective in eradicating H. pylori. However, when combined with other agents (anti-microbials, PPIs or H2 receptor antagonists), over 90% of the cases of H. pylori are eradicated. The bismuth compounds are also used to treat nausea, diarrhoea, and indigestion. Patients may experience a darkening of the tongue and stool while on bismuth therapy. Prolonged use of bismuth compounds is not advised because of possible systemic side effects (encephalopathy).
Extra info: The mechanism of anti-microbial action from bismuth is unknown. However, studies have shown that combination therapy with bismuth and an H2-antagonist is synergistic.