Effect of genetic differences in omeprazole metabolism on cure rates for Helicobacter pylori infection and peptic ulcer.

Background: Omeprazole is metabolized by S-mephenytoin 4'-hydroxylase (CYP2C19) in the liver. In persons with a poor-metabolizer genotype for CYP2C19, the therapeutic efficacy of omeprazole may be increased.
Objective: To investigate whether CYP2C19 genotype status is associated with cure rates for Helicobacterpylori infection and peptic ulcer achieved by using dual therapy with omeprazole and amoxicillin.
Design: Prospective cohort study.
Setting: University hospital and health service center in Hamamatsu, Japan.
Patients: 62 patients with peptic ulcer and H. pylori infection.
Intervention: Omeprazole and amoxicillin.
Measurements: CYP2C19 genotype status and cure rates for H. pylori infection and peptic ulcer.
Results: Cure rates for H. pylori infection were 28.6% (95% CI, 13.1% to 48.7%), 60% (CI, 38.6% to 83.0%), and 100% (CI, 66.4% to 100%) in the rapid-, intermediate-, and poor-metabolizer groups, respectively. Healing rates for both duodenal and gastric ulcer in the three groups were roughly parallel with cure rates for H. pylori infection.
Conclusion: The results of the genotyping test for CYP2C19 seem to predict cure of H. pylori infection and peptic ulcer in patients who receive dual therapy with omeprazole and amoxicillin.