title: Pharmacokinetic and pharmacodynamic interactions between omeprazole and amoxycillin in Helicobacter pylori-positive healthy subjects.
abstract: BACKGROUND
  Omeprazole with amoxycillin has been used to treat Helicobacter pylori infection. It was speculated that omeprazole-induced hypoacidity enhances the antibacterial activity of amoxycillin. Limited information exists about intragastric pH and bioavailability of amoxycillin during combination therapy. No data are available about possible effects of the antibiotic on the pharmacokinetics and pharmacodynamics of omeprazole.
  
  
  METHODS
  The study was performed in a three-way cross-over double-blind design. After a run-in period on placebo with a baseline intragastric pH-metry, 24 H. pylori-positive healthy subjects were randomly dosed with amoxycillin 750 mg b.d. + placebo, amoxycillin 750 mg b.d. + omeprazole 40 mg b.d. and omeprazole 40 mg b.d. + placebo for 5 days. On the last day of each regimen intragastric pH-metries were performed, and blood samples taken for omeprazole and amoxycillin serum profiles.
  
  
  RESULTS
  Amoxycillin monotherapy had no acid-inhibiting effect. Median pH during combined dosing was significantly lower, compared to omeprazole monotherapy (P < 0.01). Mean serum concentrations of omeprazole and amoxycillin given alone or in combination were not different.
  
  
  CONCLUSIONS
  High-dose omeprazole does not alter the pharmacokinetics of amoxycillin. The significantly lower intragastric pH during combination therapy might be due to the H. pylori-suppressive effect of this treatment.
authors.affiliation: 2nd Medical Department, Krankenhaus Am Urban, Berlin, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Pommerien
authors.forename: M
authors.initials: M
authors.lastname: Braun
authors.forename: J P
authors.initials: JP
authors.lastname: Idström
authors.forename: M
authors.initials: M
authors.lastname: Wrangstadh
authors.forename: W
authors.initials: W
authors.lastname: Londong
mesh_terms: D000328:Adult; D000658:Amoxicillin / Q000493:pharmacokinetics* / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D000897:Anti-Ulcer Agents / Q000493:pharmacokinetics* / Q000494:pharmacology*; D019540:Area Under Curve; D001944:Breath Tests; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004347:Drug Interactions; D005745:Gastric Acidity Determination; D016481:Helicobacter Infections / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D009853:Omeprazole / Q000493:pharmacokinetics* / Q000494:pharmacology*; D014508:Urea / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D000897:Anti-Ulcer Agents; D000658:Amoxicillin; D014508:Urea; D009853:Omeprazole