title: Retrospective evaluation of the effect of omeprazole on clozapine metabolism.
abstract: OBJECTIVE
  To study the effect of the replacement of omeprazole by pantoprazole on clozapine metabolism in 13 psychiatric patients, who used both clozapine and omeprazole.
  
  
  METHODS
  Retrospective study of the medical files.
  
  
  RESULTS
  In comparison to smokers, a significant rise of the serum clozapine levels was observed in all non-smoking patients, whilst the daily dose of clozapine remained unchanged. This effect was probably caused by the discontinuation of enzyme induction of the cytochrome P450 enzyme 1A2 by omeprazole in non-smokers, whereas CYP1A2 remained induced in patients who smoked.
  
  
  CONCLUSIONS
  Omeprazole only influenced clozapine metabolism in non-smokers. In none of the patients an adjustment of the clozapine dose was required.
authors.affiliation: Deltabouman Psychiatric Teaching Hospital, PO Box 800, 3170 DZ Poortugaal, The Netherlands. ejmdpz@deltabouman.nl
authors.forename: Evert J
authors.initials: EJ
authors.lastname: Mookhoek
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: Loonen
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000328:Adult; D000368:Aged; D000897:Anti-Ulcer Agents / Q000009:adverse effects*; D014150:Antipsychotic Agents / Q000493:pharmacokinetics*; D001562:Benzimidazoles / Q000009:adverse effects; D003024:Clozapine / Q000493:pharmacokinetics*; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000009:adverse effects*; D000077402:Pantoprazole; D011567:Psychiatric Department, Hospital; D011618:Psychotic Disorders / Q000188:drug therapy; D012189:Retrospective Studies; D012907:Smoking / Q000378:metabolism; D013454:Sulfoxides / Q000009:adverse effects
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000897:Anti-Ulcer Agents; D014150:Antipsychotic Agents; D001562:Benzimidazoles; D013454:Sulfoxides; D000077402:Pantoprazole; D003024:Clozapine; D009853:Omeprazole