Pharmacokinetic– pharmacodynamic analysis of the role of CYP2C19 genotypes in short-term rabeprazole-based triple therapy against Helicobacter pylori

AIMS

The aim was to explore the role of CYP2C19 polymorphism in short-term rabeprazole-based triple therapy against Helicobacter pylori infection.

METHODS

Patients with H. pylori infection were tested for CYP2C19 genotype as poor metabolizers (PMs) or extensive metabolizers (EMs, homozygous EM or heterozygous EM) and given rabeprazole for 7 days. Antibiotics (clarithromycin and amoxicillin) were given on days 1–4, days 4–7, or days 1–7. A direct link model with an effect compartment was used in the population pharmacokinetic–pharmacodynamic analysis. The status of H. pylori infection was evaluated.

RESULTS

Rabeprazole clearance was lower in CYP2C19 PMs than in EMs (with average values of 10.7 vs. 16.8 l h⁻¹ in PMs and EMs, respectively), resulting in higher plasma levels in the former group. The values of EC₅₀ and k_eo of gastrin response increased with multiple doses of rabeprazole. The k_eo values were lower in CYP2C19 PMs than in EMs on day 1 (0.012 vs. 0.017 × 10⁻⁴ l min⁻¹), and higher than in EMs on day 4 (0.804 vs. 0.169 × 10⁻⁴ l min⁻¹) of rabeprazole treatment. The predicted gastrin-time profile showed a higher response in CYP2C19 PMs than in EMs on days 4 and 7. Helicobacter pylori was eradicated in all CYP2C19 PMs except in one patient infected by a resistant strain. In contrast, in CYP2C19 EMs the eradication rates ranged from 58 to 85%.

CONCLUSIONS

CYP2C19 genotypes play a role in H. pylori eradication therapy. Rabeprazole-based short-term triple therapy may be applicable in CYP2C19 PMs for H. pylori eradication.