title: Time to maximum effect of lansoprazole on gastric pH in normal male volunteers.
abstract: BACKGROUND
  The time to maximum inhibition of gastric acidity resulting from repeated oral dosing with lansoprazole 30 mg daily for 7 days was studied in nine healthy male volunteers.
  
  
  METHODS
  Twenty-four hour intragastric pH monitoring was performed before treatment and on days 1, 3, 5 and 7 of dosing with lansoprazole. Blood samples were taken for the estimation of plasma lansoprazole concentrations.
  
  
  RESULTS
  Lansoprazole 30 mg increased mean 24-h intragastric pH to 3.57 on day 1 compared with baseline mean pH of 2.11 (P < 0.05). The mean intragastric pH during the morning period (08.00-13.00 h) was significantly higher on days 3, 5 and 7 than on day 1, but no consistent differences between day 1, 3, 5 and 7 were noted for subsequent periods (13.00-18.00, 18.00-21.00 and 23.00-07.00 h). There were no differences in mean pH between days 3, 5 and 7. Intragastric pH was maintained above pH 3 for 54.7, 60.1, 61.9 and 67.4% of the time on days 1, 3, 5 and 7, respectively. Lansoprazole pharmacokinetic parameters did not change with daily dosing. The area under the lansoprazole plasma concentration-time curve correlated with the intragastric pH (P < 0.005).
  
  
  CONCLUSIONS
  Lansoprazole 30 mg raised intragastric pH significantly from baseline on day 1 to a maximum effect as early as 6 h after the first dose. The degree and duration of acid suppression confirm the usefulness of lansoprazole for the treatment of acid-related disorders.
authors.affiliation: Department of Medicine, McMaster University Medical Centre, Hamilton, Ontario, Canada.
authors.forename: N J
authors.initials: NJ
authors.lastname: Bell
authors.forename: R H
authors.initials: RH
authors.lastname: Hunt
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000284:Administration, Oral; D000328:Adult; D000897:Anti-Ulcer Agents / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D004334:Drug Administration Schedule; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D064747:Lansoprazole; D008297:Male; D009853:Omeprazole / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D000897:Anti-Ulcer Agents; D064747:Lansoprazole; D009853:Omeprazole