http://repub.eur.nl/res/aut/39335/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/27823/ 2010-01-01T00:00:00Z Background: Esomeprazole and pantoprazole are metabolized in the liver and the polymorphic CYP2C19 enzyme is involved in that process. This genetic polymorphism determines fast (70% of Caucasians), intermediate (25-30% of Caucasians) and slow (2-5% of Caucasians) metabolism of PPIs. Aim To compare the acid-inhibitory effects of esomeprazole 40 mg and pantoprazole 40 mg at 4, 24 and 120 h after oral administration in relation to CYP2C19 genotype and pharmacokinetics. Methods CYP2C19*2, *3, *4, *5 and *17 genotypes were determined in healthy Helicobacter pylori-negative Caucasian subjects. 7 wt/wt, 7 wt/*2, 2 wt/*17, 2 *2/*17 and 1 *2/*2 were included in a randomized investigator-blinded cross-over study with esomeprazole 40 mg and pantoprazole 40 mg. Intragastric 24-h pH-monitoring was performed on days 0, 1 and 5 of oral dosing. Results A total of 19 subjects (mean age 24 years, 7 male) completed the study. At day 1 and 5, acid-inhibition with esomeprazole was significantly greater and faster than with pantoprazole. Differences in acid-inhibition and pharmacokinetics between wt/wt and wt/*2 genotype were significant for pantoprazole at day 1 and 5. Conclusions Esomeprazole provides acid-inhibition faster than and superior to pantoprazole after single and repeated administration. The acid-inhibitory effect and the kinetics of pantoprazole are influenced by CYP2C19 genotype. http://repub.eur.nl/res/pub/29676/ 2008-05-01T00:00:00Z AIMS: To investigate the impact of CYP2C19 mutations *2-*6 and *17 on acid-inhibition and pharmacokinetics of lansoprazole (L15), omeprazole (O10, O20) and pantoprazole (P40) in Caucasians. METHODS: CYP2C19 genotyping for *2-*6 and *17 mutations was assessed in subjects who were H. pylori negative in two randomized crossover trials. The influence of CYP2C19 mutations on single and repeated administration of L15 and O10 (study A) and O20 and P40 (study B) was investigated. Pharmacokinetics and the cumulative percentage of time with intragastric pH above 4 (% > pH 4) were assessed on day 1 and 6. RESULTS: For study A CYP2C19 genotyping found five *1/*1, four *1/*2, one *1/*17 and one *2/*17. For study B the results were six *1/*1, two *1/*2, six *1/*17, one *2/*2 and one *2/*17. For all PPIs AUC was highest in *2/*2 and lowest in *1/*17. On day 1, all PPIs significantly increased percentage >pH 4 compared with baseline. *1/*1 genotype showed no significant acid-inhibition after L15, O10 and O20. *1/*17 genotype showed no significant acid-inhibition after O20 and P40. *1/*2 genotype showed significant acid-inhibition after L15 and O10. On day 6, all four PPIs showed significantly increased acid-inhibition. *1/*1 and *1/*17 showed a significantly increased percentage > pH 4 after treatment with O20 and P40. However, in *1/*1 subjects percentage > pH 4 was not significantly increased after L15 and O10. *1/*2 genotype showed a significant acid-inhibitory effect after repeated dosing with L15 and O10. CONCLUSIONS: Caucasian subjects with *1/*1 and *1/*17 genotype need stronger acid-suppression therapy, especially during the first days of treatment or with on-demand therapy. http://repub.eur.nl/res/pub/35982/ 2007-01-01T00:00:00Z Background: The occurrence and the clinical relevance of rebound acid hypersecretion after discontinuation of proton pump inhibitors is unclear. Aim: To perform a systematic review of rebound acid hypersecretion after discontinuation of proton pump inhibitors. Methods: PubMed, Embase and Central were searched up to October 2005 with indexed terms. Results: Eight studies were included, sample size was 6-32. The studies used both basal and stimulated acid output as parameters to study rebound acid hypersecretion and assessed these at different time points and with variable methods. Five studies (including four randomized studies) did not find any evidence for rebound acid hypersecretion after proton pump inhibitor therapy. Of the remaining three studies, the duration of proton pump inhibitor therapy was the longest and two of these studies were the only to assess Helicobacter pylori status of their study subjects. These two studies suggested that rebound acid hypersecretion may occur in H. pylori-negatives after 8 weeks of proton pump inhibitors. Conclusions: Studies that have investigated rebound acid hypersecretion after cessation of proton pump inhibitor treatment are heterogenic in design, methods and outcome. There is some evidence from uncontrolled trials for an increased capacity to secrete acid in H. pylori-negative subjects after 8 weeks of treatment. There is no strong evidence for a clinically relevant increased acid production after withdrawal of proton pump inhibitor therapy.