Addition of metronidazole to omeprazole/amoxycillin dual therapy increases the rate of Helicobacter pylori eradication: a double-blind, randomized trial

SUMMARY Aims: To compare the efficacy, safety and tolerability of an omeprazole/amoxycillin (OA) dual therapy Helicobacter pylori eradication regimen with an omeprazole/amoxycillin/metronidazole (OAM) triple therapy regimen. Methods: In this double-blind trial, conducted in 19 hospitals, 119 patients with symptomatic duodenal ulcer disease were randomized to receive either 14 days treatment with omeprazole 40 mg daily, amoxycillin 500 mg t.d.s. and placebo followed by a further 14 days’treatment with omeprazole 20 mg daily (n= 59) or 14 days treatment with omeprazole 40 mg daily, amoxycillin 500 mg t.d.s., and metronidazole 400 mg t.d.s., followed by a further 14 days’treatment with omeprazole 20 mg daily (n= 60). H. pylori status was assessed by 13C-urea breath test at entry and at 4 weeks post-treatment. Results: H. pylori infection was eradicated in 46% of the OA treated patients and in 92% of the OAM treated patients, a mean difference of 46% (P < 0.0001, 95% CI for the difference: + 30 to + 62). In only one patient was the duodenal ulcer not endoscopically healed after 4 weeks of treatment (OA 100%; OAM 98% healed). There were no significant differences in speed of symptom relief or improvement in symptoms between the two groups. Both regimens were well tolerated, with 96% of patients completing the course, and only one patient withdrawing due to an adverse event. The only side-effect with a significantly higher incidence in the OAM group was diarrhoea, which occurred in 36% of patients compared to 16% of patients in the OA group (P < 0.05). Conclusions: A regimen consisting of omeprazole 40 mg daily, amoxycillin 500 mg t.d.s. and metronidazole 400 mg t.d.s. for 14 days gives an appreciably higher H. pylori eradication rate than omeprazole and amoxycillin alone, with acceptable tolerability.