Objective: In two studies, different regimens of omeprazole-amoxycillin-metronidazole were assessed for the eradication of Helicobacter pylori.
Design: Randomized, international, multicentre studies with parallel groups.
Setting: The studies were performed at centres in Canada, Czech Republic, France, Germany, Hungary, Sweden and UK.
Participants and interventions: H. pylori-positive patients with duodenal ulcer disease (active or in remission) were randomized to 7-day treatment with: omeprazole 40 mg once daily, amoxycillin 500 mg three times daily and metronidazole 400 mg three times daily (OAMtid; n = 242); omeprazole 20 mg twice daily, amoxycillin 1000 mg twice daily and metronidazole 800 mg twice daily (OAM800; n = 247); or omeprazole 20 mg twice daily, amoxycillin 1000 mg twice daily and metronidazole 400 mg twice daily (OAM400; n = 127).
Main outcome measures: Eradication of H. pylori.
Results: Intention-to-treat analysis revealed H. pylori eradication rates of 76% (184/242) with OAMtid, 80% (198/247) with OAM800, and 76% (97/127) with OAM400. There was considerable variation in the levels of primary resistance to metronidazole in different countries. The overall eradication rate in patients infected with metronidazole-sensitive H. pylori strains was 85% (313/370), compared with 60% (56/94) in patients harbouring metronidazole-resistant strains (P<0.001). All regimens were generally well tolerated, with mild adverse events occurring in 4-26% of patients (mainly diarrhoea, reversible increase in liver enzymes and headache).
Conclusion: The OAM combination is effective in curing H. pylori infection. Primary metronidazole resistance may reduce its effectiveness, but an increased daily dosing of metronidazole may partly overcome this problem.