Ulcer Therapy using Bismuth Compounds

Paracelsus made the general introduction of several heavy metals into medicine in the 16th century and nowadays the particular use of bismuth compounds is focused upon the treatment of disorders of the alimentary system (14 such drugs are commonly prescribed in Britain). Several of these medicines are based upon a red viscous colloidal bismuth citrate solution containing ammonium hydroxide plus a colourant, a sweetening agent and emollients such as sorbitol or glycerine at pH = 10. 

Even though most stomach ulcers are treated by gastric acid secretory inhibitors or H2-receptor (histamine) blockers such as cimetidine, the simulation technique has led to formulations that produce bismuth patches on ulcers at other sites having other pH values. However, the optimization of conditions for ulcer healing is very difficult using clinical trials because of the vagaries of ulceration and of responses to therapy, some 80% of ulcers reoccurring within a year. 

It is fascinating to note the recent re-awakening of interest in bismuth therapies since the discovery in 1982 that the intestinal bacterium Helicobacter pylori may well initiate ulcer formation by excreting acid. Bismuth, in common with many heavy metals, is bactericidal and so the lasting effects of bismuth citrate therapy may well be a combination of ulcer healing (from the precipitates) as well as ulceration initiator suppression (from the bacteriocidal action). In vitro the organism is sensitive to bismuth but results in vivo are feeble. However, combinations of bismuth with antibiotics such as amoxicillin or tetracycline have success rates of 80%, i.e. four times the 20% success rate described above. 

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