bismuth-subsalicylate and ranitidine-bismuth-citrate

Topics: Anti-Bacterial Agents; Anti-Ulcer Agents; Bismuth; Drug Therapy, Combination; Helicobacter Infections; Helicobacter pylori; Humans; Organometallic Compounds; Proton Pump Inhibitors; Ranitidine; Salicylates; Virulence

Bismuth salts have been used in medicine for over three centuries, particularly in the treatment of dyspepsia. Commonly used agents include colloidal bismuth subcitrate (CBS), bismuth subsalicylate (BSS) and the newer ranitidine bismuth citrate (RBC). These are safe drugs which exert local effects on the gastroduodenal mucosa. Gastric mucosal levels of bismuth exceed the concentrations required to kill Helicobacter pylori in vitro. The mechanisms of actions of bismuth on gastrointestinal pathogens including H. pylori are complex and include inhibition of protein and cell wall synthesis, membrane function and ATP synthesis. Adherence of H. pylori to surface epithelial cells is also impaired. Bismuth monotherapy is effective in vivo to suppress H. pylori but cure rates are low. CBS, BSS and RBC have synergistic activity with one or two antibiotics and are effective in eradicating H. pylori. CBS and RBC also exert other effects on the mucosa including cytoprotective and ulcer healing properties. In addition, RBC is effective in inhibiting gastric acid secretion.

Topics: Anti-Bacterial Agents; Bismuth; Drug Synergism; Duodenum; Gastric Acid; Gastric Mucosa; Helicobacter Infections; Helicobacter pylori; Histamine H2 Antagonists; Humans; Organometallic Compounds; Ranitidine; Salicylates; Treatment Outcome

Bismuth compounds remain useful for Helicobacter pylori eradication therapy. These include colloidal bismuth subcitrate (CBS), bismuth subsalicylate (BSS) and, most recently, ranitidine bismuth citrate (RBC). CBS appears to prevent the development of imidazole resistance when coadministered with nitroimidazoles. Traditional triple therapy with bismuth, metronidazole and tetracycline or amoxicillin (BMT/A) only partially overcomes metronidazole resistance. However, the addition of a PPI to bismuth triple therapy largely overcomes established metronidazole resistance if treatment is given for at least one week or more. When RBC rather than PPI is used with clarithromycin, this dual regimen appears to be more effective in preventing the development of secondary clarithromycin resistance. The triple combination of RBC, metronidazole and clarithromycin appears to be effective against metronidazole resistant strains of H pylori. Thus, overall, there is some evidence that bismuth compounds may prevent the development of antibiotic resistance and that existing antibiotic resistance may at least be partially overcome in vitro and in vivo. With the growing emergence of H pylori resistance to metronidazole and clarithromycin, further research to clarify the role of bismuth compounds is required.

Topics: Anti-Bacterial Agents; Anti-Ulcer Agents; Bismuth; Clarithromycin; Drug Resistance, Microbial; Drug Therapy, Combination; Helicobacter Infections; Helicobacter pylori; Humans; Organometallic Compounds; Ranitidine; Salicylates