Sa1048 Comparison of Gastric Acid Inhibition With 4-Times-Daily Dosing of Esomeprazole and Rabeprazole in Healthy Japanese Individuals

Abstract

Background: Potent neutralization of intragastric pH is important in the treatment of acidrelated diseases such as peptic ulcers and gastroesophageal reflux disease (GERD). However, once (o.i.d.)or twice (b.i.d.)-daily dosing of a standard dose of proton pump inhibitors (PPIs) does not always provide sufficient acid inhibition over a 24-h period, particularly for rapid metabolizers (RMs) of CYP2C19. We previously reported that esomeprazole (b.i.d.) exerts [check] potent acid inhibition in CYP2C19 RMs compared to omeprazole, lansoprazole, and rabeprazole, and that complete inhibition of gastric acid secretion in all patients is difficult. Although rabeprazole (10 mg, q.i.d.) and lansoprazole (30 mg, q.i.d.) reportedly induce sufficient acid inhibition in CYP2C19 RMs, whether or not esomeprazole (20 mg, q.i.d.) can induce sufficient inhibition over a 24-h period in RMs remains unclear. We therefore examined the efficacy of esomeprazole q.i.d. in achieving sufficient acid inhibition. Methods: In a randomized cross-over study, 30 healthy, Helicobacter pylori-negative, young Japanese volunteers (10 RMs, 10 intermediate metabolizers [IMs], and 10 poor metabolizers [PMs] of CYP2C19) received esomeprazole 20 mg b.i.d. or q.i.d. for 1 week. Intragastric pH monitoring was performed on Day 7. Intragastric pHs were also compared to esomeprazole 20 mg q.i.d. and rabeprazole 10 mg q.i.d. (13 RMs, 15 IMs and 7 PMs). Data from 24-h pH monitoring from our previous study of the efficacy of rabeprazole 10 mg q.i.d was used for comparison. Results: Median pH attained with esomeprazole 20 mg b.i.d. differed