Gastric pH and Gastric Residence Time in Fasted and Fed Conscious Beagle Dogs Using the Bravo® pH System

To further characterize the time course of gastric pH with respect to meals and gastric residence times (GRTs) in dogs, continuous pH measurements were recorded with Bravo (R) capsules, which were attached to the dogs' stomach mucosa or administered as free capsules, respectively. Experiments took place in home or study cages, and meals were administered at designated times. Up until 2 h prior to mealtime, the fasted gastric pH remained constantly acidic (similar to 2.0) regardless whether the dogs were in the study or home cages. However, as feeding time became imminent, the pH was typically elevated for dogs in home cages, whereas the pH remained acidic for dogs in study cages. For both monitoring locations, the gastric pH remained acidic during meal consumption and for at least 10 h after meals. The GRT between fasted (25 +/- 32 min) and fed (686 +/- 352 min) conditions was significantly different with considerable inter-and intrasubject variability. Fasted gastric pH was similar to that of literature monkey and human values but differed after meals as the dog gastric pH remained acidic unlike monkey and human. In dogs, the fasted GRT was remarkably rapid and under fed conditions, longer than that observed in humans. (C) 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:2439-2448, 2012