title: Influence of omeprazole on pharmacokinetics of domperidone given as free base and maleate salt in healthy Chinese patients.
abstract: OBJECTIVE
  To investigate the influence of omeprazole on the pharmacokinetics of domperidone given as free base and maleate salt.
  
  
  METHODS
  An open, randomized, 2-period crossover study with a washout period of 7 d was conducted in 10 healthy Chinese, male patients. In each study period, the patients were administered a single oral dose of 10 mg domperidone as free base or maleate salt on d 1, 20 mg omeprazole twice daily on d 2 and 3, and once on d 4. A single dose of 10 mg domperidone as free base or maleate salt was taken at 4 h after administration of omeprazole on d 4. Plasma samples were collected on d 1 and 4 after the administration of domperidone, and the plasma concentrations of domperidone were determined by a sensitive liquid chromatography-tandem mass spectrometry method.
  
  
  RESULTS
  For free-base domperidone, pretreatment with omeprazole resulted in a 16% decrease in maximum concentration (C(max)), compared with administration alone (P<0.05). However, for maleate salt, with the exception of an increase in t(1/2), no pharmacokinetic parameters were significantly changed. When the free base and maleate salt were administered alone, no differences were found in any parameters between the 2 formulations. In contrast, when they were administered in the presence of omeprazole, the C(max) of domperidone given as free base was lower (25.9%) than that given as maleate salt (P<0.05).
  
  
  CONCLUSIONS
  Pretreatment of omeprazole does not affect the absorption of domperidone maleate, but leads to a moderately decreased rate of absorption of the free base.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yi-fan
authors.initials: YF
authors.lastname: Zhang
authors.forename: Xiao-yan
authors.initials: XY
authors.lastname: Chen
authors.forename: Xiao-jian
authors.initials: XJ
authors.lastname: Dai
authors.forename: Yi-ni
authors.initials: YN
authors.lastname: Zhang
authors.forename: Qi-zhi
authors.initials: QZ
authors.lastname: Liu
authors.forename: Hua-ling
authors.initials: HL
authors.lastname: Yu
authors.forename: Da-fang
authors.initials: DF
authors.lastname: Zhong
mesh_terms: D000328:Adult; D000897:Anti-Ulcer Agents / Q000494:pharmacology*; D019540:Area Under Curve; D018592:Cross-Over Studies; D004294:Domperidone / Q000493:pharmacokinetics*; D018492:Dopamine Antagonists / Q000493:pharmacokinetics*; D004347:Drug Interactions; D006801:Humans; D008297:Male; D009853:Omeprazole / Q000494:pharmacology*
chemical_list: D000897:Anti-Ulcer Agents; D018492:Dopamine Antagonists; D004294:Domperidone; D009853:Omeprazole