Objective To investigate whether the acid-inhibitory efficacy of omeprazole capsule are dependent of the
cytochromeP450 2C19
(CYP 2C19) genotype status. Methods Fifteen H. pylori-negative healthy volunteers were invited and approved to participate in this study ,whose CYP2 C19 genotype status were determined by polymerase chain reaction-restriction fragment length polymorphism method. There were five homozygous extensive metabolisers(hom EMs), five heterozygous extensive metabolisers(het EMs) and five poor metabolisers(PMs). After orally received omeprazole 20 mg once daily in the morning, the intragastric pH values were monitored for 24 h by Digitrapper pH on the first day and the eighth day. Results Significant differences were observed in median intragastric pH values, pH>4 holding time, pH>3 holding time between PMs and the others(hom EMs and het EMs) after a single dose or repeated doses. The increased intragastric pH values from single to repeated doses were more significant in the hom EM and het EM groups than that in PM groups.The acid suppression at night(22:00-6:00) in PM groups was also more significant than that in the hom EM and het EM groups. Conclusion CYP 2C19
genetic polymorphism has significant influence on acid-inhibitory efficacy of omeprazole and nocturnal acid breakthrough.