title: Estimation of gastric pH in cynomolgus monkeys, rats, and dogs using [(13)C]-calcium carbonate breath test.
abstract: BACKGROUND
  The determination of gastric pH is important for the confirmation of efficacy of anti-secretory drugs. However, current methods for measurement of gastric pH provide significant stress to animals and humans.
  
  
  OBJECTIVE
  The objective of this study is to establish an easy and reliable gastric pH measurement method by determining (13)CO2 concentration in expired air of monkeys, dogs, and rats after oral administration of Ca(13)CO3.
  
  
  METHODS
  A correlation of (13)CO2 concentration determined by a Ca(13)CO3 breath test with gastric pH just before Ca(13)CO3 administration was analyzed in the 3 animal species. The equations and contribution ratios of regression line were calculated from logarithmic (13)CO2 concentrations at 15min after administration of Ca(13)CO3 using the linear regression analysis.
  
  
  RESULTS
  The (13)CO2 concentration in the Ca(13)CO3 breath test was well correlated with the gastric pH just before Ca(13)CO3 administration in the 3 animal species (r=-0.977 to -0.952). The equations of regression line between the (13)CO2 concentration and the gastric pH in each animal species showed good contribution ratios (R(2)≥0.89).
  
  
  CONCLUSIONS
  The Ca(13)CO3 breath test is an informative tool to estimate gastric pH in animals and will be applicable as a new noninvasive tool for patients with GERD/PPI-resistant symptoms.
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan. Electronic address: tobitak@otsuka.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Tobita
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Inada
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
authors.forename: Asuka
authors.initials: A
authors.lastname: Sato
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan.
authors.forename: Kimiyoshi
authors.initials: K
authors.lastname: Sudoh
authors.affiliation: Department of Pharmacokinetics/Pharmacodynamics, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sato
mesh_terms: D000818:Animals; D000863:Antacids / Q000008:administration & dosage*; D001944:Breath Tests; D002119:Calcium Carbonate / Q000008:administration & dosage*; D002245:Carbon Dioxide / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis; D004285:Dogs; D005744:Gastric Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D008252:Macaca fascicularis; D054328:Proton Pump Inhibitors; D051381:Rats; D012044:Regression Analysis
chemical_list: D000863:Antacids; D002247:Carbon Isotopes; D054328:Proton Pump Inhibitors; D002245:Carbon Dioxide; D002119:Calcium Carbonate
keywords: Breath test; Ca(13)CO(3); Gastric pH; Proton pump inhibitor