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Pharmacology
When present in the stomach and duodenum, bismuth salts act locally to stimulate prostaglandin production, coat ulcer surfaces, inhibit the proteolytic action of pepsin and kill H. pylori. Bismuth has long been available as tripotassium dicitratobismuthate (colloidal bismuth subcitrate). Ranitidine bismuth citrate is a molecular combination of ranitidine, an H 2 -receptor antagonist, and a bismuth citrate complex. It was developed with the aim of generating a single product with antisecretory activity and bismuth-related ulcer healing and anti-H. pylori actions.
Under 1% of the bismuth contained within swallowed ranitidine bismuth citrate is absorbed and subsequently passes into the urine. 2 Plasma bismuth has an elimination half-life of about 5-10 days. The summary of product characteristics (SPC) states that ranitidine taken in the combination is absorbed rapidly, cleared primarily by the kidney and has an elimination half-life of about 3 hours.
Clinical studies
Ulcer healing
In a randomised controlled trial involving a total of 1620 patients with active duodenal ulceration, 4 weeks of treatment with ranitidine bismuth citrate 200mg twice daily healed ulcers in 79% of patients, 400mg twice daily in 85%, 800mg twice daily in 84% and ranitidine 150mg twice daily in 81%. 3 The differences between these healing rates were not statistically significant. In a study (published as an abstract) of 638 patients with gastric ulcers, 8-week treatment with ranitidine bismuth citrate 400mg twice daily and 800mg twice daily were equally effective, giving healing rates of 86%. 4 Healing rates with ranitidine bismuth citrate 200mg twice daily (72%) and ranitidine 150mg twice daily (76%) were significantly lower. Ranitidine bismuth citrate has not been compared with either omeprazole or lansoprazole which, in other trials, have each healed over 90% of duodenal and gastric ulcers. 5 , 6
Eradication of H. pylori infection
In infected patients, ranitidine bismuth citrate alone rarely eradicates H. pylori. 7 - 11 The drug has been used with either clarithromycin or amoxycillin in trials of duodenal ulcer healing and H. pylori eradication. 7 - 11 But in all of these studies the control treatments and primary end-points used make it difficult to assess the value of such regimens in clinical practice.
Trial design - In each of the trials, patients were randomised to receive either ranitidine bismuth citrate for...