Current treatment regimens for Helicobactor pylori infection are complex and difficult to complete, often consisting of four medications taken at varying times during the day. These regimens eradicate H. pylori infections in nearly 80 percent of cases. Newer twice-daily regimens are simpler and have similar eradication rates. However, little is known about the effectiveness of once-daily therapy. Laine and associates reviewed the safety and efficacy of four once-daily treatment regimens for H. pylori infections.

Adults who had gastrointestinal symptoms or who wished to be tested for H. pylori infection were eligible for the study. Patients with evidence of H. pylori infection confirmed by endoscopic-directed biopsies or rapid quantitative serologic tests plus a C-urea breath test were randomized to one of four treatment groups. The first group received omeprazole, in a dosage of 80 mg, and metronidazole, in a dosage of 750 mg, once daily for 10 days. Patients in the other three groups received the same daily omeprazole-metronidazole (OM) regimen along with one of the following agents: amoxicillin, in a dosage of 1.5 g daily for 10 days; azithromycin, in a dosage of 500 mg daily for seven days; or clarithromycin, in a dosage of 1 g daily for 10 days. At the end of the study a clinical examination, side effect profile, compliance rate and cure rate were obtained for all patients.

A total of 160 patients were enrolled in the study, with 40 patients in each treatment group. Eradication of infection was highest in the group taking the OM regimen plus clarithromycin (78 percent); the OM regimen plus azithromycin was slightly less effective (65 percent). However, the combination of OM with clarithromycin also had the highest rates of noncompliance and drop-out, primarily because of gastrointestinal disturbances. The OM regimen alone rarely resulted in a cure (8 percent), and the OM regimen with amoxicillin was significantly lower (35 percent) in effectiveness than the other combination regimens.

The authors conclude that combination therapy with once-daily OM plus either clarithromycin or azithromycin resulted in cure rates within the range of the more complicated regimens. However, the authors also emphasize that despite these promising results, more study of once-daily regimens is needed before they can replace the well-studied regimens currently in place.