title: Effect of CYP2C19*2 and *17 mutations on pharmacodynamics and kinetics of proton pump inhibitors in Caucasians.
abstract: BACKGROUND
  The influence of CYP2C19 on the kinetics and dynamics of omeprazole, lansoprazole and rabeprazole has been studied in Japanese subjects. * It has been suggested that subjects with *1/*1 genotype might need stronger acid suppression than *1/*2 and *2/*2 subjects. This suggestion comes from data in Japanese subjects and has not been confirmed in Caucasians. * Furthermore, a novel CYP2C19 mutation, *17, which mainly occurs in Caucasians has been discovered. This mutation has been associated with clinical failure, but its relevance for therapy with PPIs has not been studied yet.
  
  
  CONCLUSIONS
  In this study, the influence of CYP2C19 on both the pharmacokinetics and dynamics in Caucasian subjects after single and repeated dosing has been investigated. * This is the first study showing that Caucasian subjects with *1/*1 and *1/*17 mutations need stronger acid-inhibition. In this study three proton pump inhibitors (omeprazole, lansoprazole and pantoprazole, in different doses) were studied of which pantoprazole had not been studied before in this setting, not even in Japanese.
  
  
  OBJECTIVE
  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.
authors.affiliation: Central Hospital Pharmacy, the Hague, The Netherlands.
authors.forename: Nicole G
authors.initials: NG
authors.lastname: Hunfeld
authors.forename: Ron A
authors.initials: RA
authors.lastname: Mathot
authors.forename: Daan J
authors.initials: DJ
authors.lastname: Touw
authors.forename: Ron H
authors.initials: RH
authors.lastname: van Schaik
authors.forename: Paul G
authors.initials: PG
authors.lastname: Mulder
authors.forename: Paul F
authors.initials: PF
authors.lastname: Franck
authors.forename: Ernst J
authors.initials: EJ
authors.lastname: Kuipers
authors.forename: William P
authors.initials: WP
authors.lastname: Geus
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000493:pharmacokinetics; D000328:Adult; D000897:Anti-Ulcer Agents / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D018592:Cross-Over Studies; D065731:Cytochrome P-450 CYP2C19; D005260:Female; D005745:Gastric Acidity Determination; D006801:Humans; D064747:Lansoprazole; D008297:Male; D006899:Mixed Function Oxygenases / Q000235:genetics*; D009154:Mutation / Q000235:genetics*; D009853:Omeprazole / Q000493:pharmacokinetics; D000077402:Pantoprazole; D054328:Proton Pump Inhibitors / Q000493:pharmacokinetics*
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000897:Anti-Ulcer Agents; D054328:Proton Pump Inhibitors; D064747:Lansoprazole; D000077402:Pantoprazole; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole