CYP2C19 genotype–related efficacy of omeprazole for the treatment of infection caused by Helicobacter pylori

Objectives Omeprazole is used for the treatment of infection caused by Helicobacter pylori, and it is metabolized by the polymorphic cytochrome P4502C19 (CYP2C19). We have found that the anti–H pylori efficacy by the combination of omeprazole and antibiotics is related to the CYP2C19 genotype. Methods One hundred eight patients with cultured H pylori –positive gastritis or peptic ulcer were treated with three regimens: quadruple treatment without proton pump inhibitors (n = 25), dual treatment with omeprazole and amoxicillin (INN, amoxicilline) (n = 26), and triple treatment with omeprazole, amoxicillin, and clarithromycin (n = 57). The CYP2C19 genotype was determined by the polymerase chain reaction– restriction fragment length polymorphism (PCR‐RFLP) method and the assessment of the eradication of H pylori was based on all negative examinations, including culture, histology, and 13C‐urea breath test. Results The eradication rates for the extensive metabolizers were 50% and 86% for the dual and triple treatments, respectively. In contrast, all of the poor metabolizers treated with omeprazole and antibiotics (n = 15) showed an eradication of H pylori. Conclusion The anti–H pylori effect of dual treatment is highly efficient for CYP2C19 poor metabolizers, which suggests that clarithromycin is not necessary as a first line of therapy for this type of patients. Genotyping can provide a choice for the optimal regimen based on individual CYP2C19 genotype. Clinical Pharmacology & Therapeutics (1999) 66, 528–534; doi: