title: Acid-suppressive effects of generic omeprazole: comparison of three brands of generic omeprazole with original omeprazole.
abstract: BACKGROUND
  Generic omeprazole contains the same active ingredient as original omeprazole and require verification of the bioequivalence with original omeprazole. However, very few clinical studies have been reported.
  
  
  OBJECTIVE
  A prospective, randomised, open-label, crossover study to compare acid-suppressive effect of generic omeprazole with that of original omeprazole.
  
  
  METHODS
  Seven healthy Helicobacter pylori-negative subjects of CYP2C19 extensive metaboliser.
  
  
  METHODS
  Intragastric pH was measured for 24 h without medications (placebo) and on day 7 of repeated administration of 10 mg once daily after breakfast of original omeprazole, Omeprazon, or three brands of generic omeprazole, Omeprazole-Towa, Ovulanze or Omerap.
  
  
  RESULTS
  Median values of intragastric pH and percentages of time with pH>4 for 24 h were significantly higher with administration of any omeprazole formulation compared with placebo (P<0.05, Wilcoxon signed-rank test). Whereas, during the night-time period (20:00-08:00 h), percentages of time with pH>4 with Omeprazole-Towa and Omerap were not significantly higher than placebo. Compared with Omeprazon, these two parameters for 24 h showed significantly greater inter-subject variations with Omeprazole-Towa (P<0.05 and P<0.01, F-test) and Ovulanze (P<0.05).
  
  
  CONCLUSIONS
  Acid-suppressive effects of some brands of generic omeprazole are not the same as original omeprazole. These differences might be reflected in clinical outcomes.
authors.affiliation: Department of General Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. tshima@hiroshima-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Shimatani
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: H
authors.initials: H
authors.lastname: Mieno
authors.forename: S
authors.initials: S
authors.lastname: Tazuma
mesh_terms: D000328:Adult; D000897:Anti-Ulcer Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001189:Aryl Hydrocarbon Hydroxylases / Q000187:drug effects; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D065731:Cytochrome P-450 CYP2C19; D016568:Drugs, Generic; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D005744:Gastric Acid / Q000378:metabolism; D005745:Gastric Acidity Determination; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism; D005838:Genotype; D016480:Helicobacter pylori; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007564:Japan; D008297:Male; D006899:Mixed Function Oxygenases / Q000187:drug effects; D009853:Omeprazole / Q000008:administration & dosage* / Q000493:pharmacokinetics; D011446:Prospective Studies; D012016:Reference Values; D013810:Therapeutic Equivalency
chemical_list: D000897:Anti-Ulcer Agents; D016568:Drugs, Generic; D004791:Enzyme Inhibitors; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole