Study of esomeprazole and rabeprazole on 24-hour intragastric acid control in healthy volunteers

Objective To compare the efficacy and tolerability of esomeprazole and rabeprazole on intragastric acid suppression in healthy volunteers. Methods Thirty six healthy volunteers (twenty six males and ten females) were enrolled and randomly divided into two groups. All the subjects were administrated either esomeprazole 40 mg or rabeprazole 10 mg once daily for 5 days and then cross over repeated dosing with a 14 day washout interval. Intragastric pH was monitored continuously for 24 hours on day 1 and day 5. CYP 2C19 genotypes were determined to differentiate the extensive metabolizers (EMs) from poor metabolizers (PMs) by PCR method. Results Percentage of intragastric pH 4 was found significantly higher in esomeprazole group than in rabeprazole group during first 4 hours (58.9% vs 32.1%), 24 hours on day 1 (73.7% vs 54.8%) and 24 hours on day 5 (84.2% vs 76.2%) (P0.001, respectively). There was also a significant differences of median intragastric pH between esomeprazole and rabeprazole during the first 4 hours (4.29 vs 2.88), day 1 (5.60 vs 4.26) and day 5 (6.38 vs 5.77) ( P 0.001, respectively). The percentage of intragastric pH 4 for at least 16 hours on day 1 and day 5 was higher in esomeprazole group than in rabeprazole group (day 1 63.9% vs 33.3%, day 5 88.9% vs 61.1%, P 0.05 respectively). Of 36 subjects, 28 were EMs genotype and 8 PMs genotype. There was no statistical significance on intragastric pH between the PM and EM groups. Conclusion Both esomeprazole and rabeprazole had safe and therapeutic effect of acid suppression, while esomeprazole 40 mg revealed more effective and rapid response than rabeprazole 10 mg. There was no significant difference of intragastric acid control between EM and PM CYP 2C19 genotypes.