BACKGROUND AND AIM: The genetic polymorphism of cytochrome P450 (CYP) 2C19 has been shown to influence the efficacy of Helicobacter pylori eradication therapy with a proton pump inhibitor (PPI) and amoxicillin (so-called dual therapy). Omeprazole, a widely used PPI, and rabeprazole, a new PPI, are metabolized in different pathways in terms of CYP2C19 genetic polymorphisms. In this study, we compared the efficacy of omeprazole and rabeprazole in a 2-week dual therapy in relation to CYP2C19 polymorphism. METHODS: One hundred and ninety-nine patients with peptic ulcer disease were randomly assigned to receive one of the following regimens: 500 mg t.i.d. amoxicillin together with either 20 mg b.i.d. omeprazole or 10 mg b.i.d rabeprazole. The eradication of H. pylori was evaluated by using a bacterial culture and a [(13)C]-urea breath test at 1--2 months after completion of treatment. Cytochrome P4502C19 polymorphism was analyzed by using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: Intention-to-treat-based cure rates for the omeprazole or rabeprazole regimens were 66.3% (95% CI, 56--75) and 62.4% (95% CI, 52--71), respectively, without significant difference. Cytochrome P4502C19 genetic polymorphism did not influence the cure rates in either of these regimens. We analyzed various factors associated with treatment failure (PPI, CYP2C19 genotype, and smoking habit) by using multiple logistic regression; smoking was the only significant independent factor for treatment failure. CONCLUSION: Omeprazole and rabeprazole were equally effective in combination with amoxicillin in eradicating H. pylori, irrespective of the PPI used (omeprazole or rabeprazole) and CYP2C19 genetic polymorphism. Smoking significantly decreased the cure rate of H. pylori infection in the dual therapy.
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