Background: Proton pump inhibitors (PPIs) are affected by cytochrome P450 2C19 (CYP2C19) polymorphisms. This study compared the effect of two PPIs on early symptom relief in Japanese patients with reflux esophagitis, classified by the CYP2C19 phenotype.
Methods: Patients with reflux esophagitis were randomised to treatment with omeprazole 20 mg or rabeprazole 10 mg once daily. The CYP2C19 phenotype [homozygous extensive metaboliser (homoEM), heterozygous extensive metaboliser (heteroEM) or poor metaboliser (PM)] of each patient was determined. The primary efficacy endpoint was early, sufficient (Global Overall Symptom scale score 1 or 2), sustained (maintained for ≥7 days) reflux symptom relief.
Results: Of the 199 patients included in this analysis, the proportion achieving sufficient, sustained reflux symptom relief was higher with omeprazole than with rabeprazole on day 1 (35.6 vs. 22.4%; p = 0.041) and day 2 (43.6 vs. 28.6%; p = 0.028); there was no significant difference between the two groups on days 3-7. Among patients with the CYP2C19 PM phenotype, sufficient, sustained reflux symptom relief was higher with omeprazole than with rabeprazole on days 4-7 (62.5-66.9 vs. 31.6%; p ≤ 0.03); differences were not significant on days 1-3, or among those with the homoEM or heteroEM phenotypes on days 1-7.
Conclusions: In Japanese patients with reflux esophagitis, omeprazole 20 mg is more effective than rabeprazole 10 mg at achieving early, sufficient, sustained reflux symptom relief in individuals with the CYP2C19 PM phenotype, and is similarly effective to rabeprazole 10 mg in those with heteroEM or homoEM phenotypes.