The absorption of warfarin from the rat stomach in situ.

The absorption of warfarin from rat stomach was studied in situ by measuring the warfarin concentration in the gastric fluid, plasma, and the gastric wall concurrently. The warfarin concentrations in gastric fluid with initially acidic pH (pH 3 and pH 5) declined more rapidly than in initially neutral (pH 7) or basic (pH 8) fluid. However, the concurrent measurement of warfarin concentrations in plasma revealed that the absorption from initially neutral or basic fluids was faster in comparison with that measured from initially acidic milieu. This discrepancy resulted from a substantial accumulation of warfarin in the gastric wall mainly on mucosa due to the precipitation of the drug in acidic environment.