The Role of CYP2C19 on the Eradication of H. Pylori Infection:Implication of PK/PD Relationships

Helicobacter pylori in known to be closely associated with the pathogenesis of gastroduodenal disorders such as peptide ulcer. Eradication of this bacterium is important in the treatment of these diseases as well as in the reduction of the recurrence. The one-week triple therapy with proton pump inhibitors (PPIs) is now considered to be the standard therapies in the treatment of Helicobacter pylori infection, providing more than 80% eradication rates with few adverse effects. PPIs are mainly metabolized by CYP2C19, which is known to exhibit polymorphisms in both its genotype and phenotype. Based on the PK/PD results of our study on PPI, recently, we have proposed that CYP2C19 poor metabolizers might be subject to advantageous conditions, especially after day-4, for the treatment of H. pylori infection when 20 mg rabeprazole was given twice daily. Our results also suggest a possibility to start the triple therapy on day-4 of rabeprazole treatment to ensure the optimal acid suppression effect for antibiotics to exert the bacteriocidal effect. To find the rationale and the optimal dosing regimen for the eradication of H. pylori infection using different proton pump inhibitors, volunteers of four groups would be included in this study. PPI (rabeprazole or esomeprazole) is given for 7 days. Antibiotics are given starting from day-1 or day-4 of PPI dosing. The eradication rate of H. pylori infection and the PK/PD of PPIs are also evaluated.