Background: The clinical outcome of acid-related disorders treated by proton pump inhibitors (PPIs) might be dependent on the polymorphically expressed cytochrome P450 (CYP) 2C19, which is involved in PPI metabolism. We tested whether esomeprazole-induced healing of gastroesophageal reflux disease (GERD) is related to CYP2C19 genotype.
Methods: Two hundred five patients with GERD (Los Angeles classification grade A or B) were included in a case-control study according to endoscopic outcome (healed versus unhealed group, matched for confounders) after treatment with 40 mg esomeprazole daily for 4 weeks. The frequency of CYP2C19 genotypes was determined as the primary outcome measure for both groups. In a second trial plasma levels of esomeprazole and corresponding CYP2C19 and CYP3A4 metabolites (5-hydroxyomeprazole and omeprazole sulfone) were monitored in 10 CYP2C19 wild-type patients with GERD after the first and last doses (day 7) of 40 mg esomeprazole daily to calculate metabolic ratios.
Results: CYP2C19 wild-type (n = 148) and heterozygous (n = 51) or homozygous variant (n = 6) patients did not differ with respect to baseline characteristics. The frequency distribution of CYP2C19 genotypes was not different between patients with complete (75/100) and incomplete (73/105) healing (P = .65). When a single esomeprazole dose and multiple dosing were compared, the low contribution of CYP2C19 to the elimination of esomeprazole decreased further by 50%. In contrast, the CYP3A4-dependent formation of omeprazole sulfone increased by 40%, and consequently, the metabolic ratio of omeprazole sulfone to 5-hydroxyomeprazole was elevated from 7.9 to 19.3 (P = .0004).
Conclusion: In contrast to other PPIs, esomeprazole-induced healing of GERD is unrelated to the CYP2C19 genotype, which can be explained by the metabolic shift toward the CYP3A4-mediated pathway.