Objective: Proton pump inhibitors, metabolized by the polymorphic enzyme cytochrome P450 (CYP) 2C19, are essential drugs for Helicobacter pylori eradication. It was reported that patients with CYP2C19 wild type in Asia had lower eradication rates. This study tests the hypothesis that CYP2C19 wild type ( wt/wt ) in white patients is also associated with a higher probability of treatment failure.
Methods: This was a cohort study involving 131 H pylori -positive white (German) patients treated by quadruple therapy including lansoprazole (30 mg twice daily for 5 days). Eradication success, as well as lansoprazole trough steady-state serum concentrations, was determined according to different CYP2C19 genotypes.
Results: We found 3 homozygous variant patients (2.3%) ( mt/mt, CYP2C19*2/*2 ), 42 heterozygous patients (32.1%) ( wt/mt, CYP2C19*1/*2 ), and 86 wild-type individuals (65.6%). Significant differences in eradication success could be found between wt/wt patients (80.2%) versus combined mt/mt (100%) and wt/mt patients (97.8%) ( P <.01; odds ratio, 10.8 [confidence interval, 1.4-84]), which were associated with corresponding changes in the serum levels of lansoprazole (median, 753 ng/mL for mt/mt, 59 ng/mL for wt/mt, and 21 ng/mL for wt/wt; P <.001). Apart from antibiotic resistance, CYP2C19 polymorphism was the most important influencing factor for eradication success on multivariate analysis ( P <.0001).
Conclusion: Eradication rates of H pylori highly depend on CYP2C19 in white patients if standard doses of lansoprazole (30 mg twice daily) are administered within a quadruple regimen. Because wt/wt individuals have lower eradication rates and lower serum concentrations of lansoprazole, these patients might benefit from a higher proton pump inhibitor dosage.