Clarithromycin and omeprazole as helicobacter pylori eradication therapy in patients with H. pylori-associated gastric disorders.

Helicobacter pylori is susceptible to many antibacterial drugs in vitro but has proved difficult to eradicate in vivo. The macrolide clarithromycin has good activity against H. pylori in vitro and has demonstrated the highest eradication rate for any antibacterial monotherapy in vivo. However, it is clear that antibacterial monotherapy is not a sufficiently effective treatment for patients with H. pylori infection. The suggestion that high intragastric acidity impairs the action of antibacterial drugs led to the evaluation of combination H. pylori eradication regimens including H+,K+-ATPase inhibitors and antibacterial drug(s) with or without bismuth compounds. Noncomparative studies evaluating the efficacy of dual therapy with clarithromycin plus omeprazole in patients with H. pylori infection have reported eradication rates of between 58 and 83% > or = 4-weeks after therapy. In comparative studies, clarithromycin plus omeprazole was at least as effective as amoxicillin plus omeprazole. However, direct comparisons have shown that eradication rates achieved by dual therapy are not as high as those achieved by triple therapy. Indeed, triple therapy with clarithromycin plus omeprazole in combination with amoxicillin or a nitroimidazole has achieved eradication rates of up to 100%. Although 14-day triple drug regimes were initially considered necessary for effective eradication, it now seems clear that 7-day regimes are equally effective. Factors known to influence response to H. pylori eradication therapy include bacterial resistance and patient compliance. A review of 4 studies evaluating the efficacy of dual eradication therapy with clarithromycin plus omeprazole reported an overall incidence of adverse events (patient or investigator reported, whether related to treatment or not) of 45%. The most common adverse event was taste disturbance (an adverse event commonly reported during the development of clarithromycin); nausea, headache, diarrhoea, vomiting and abdominal pain occurred less frequently. Although dual therapy might be expected to cause fewer adverse events than triple therapy this has not been the case in direct comparisons conducted to date. Thus, although clarithromycin plus omeprazole is associated with an H. pylori eradication rate of approximately 70%, 1 week of triple therapy with these 2 drugs together with amoxicillin or a nitroimidazole, which eradicates the organism in approximately 90% of cases, may represent optimal H. pylori eradication therapy.