Gastrointestinal absorption of sulpiride in rat.

A two-compartment model could be used to describe the elimination of sulpiride from plasma after intravenous administration of 25 and 50 mg/kg doses to rat. The absolute bioavailability after oral administration was only about 15% which was also the level after intraduodenal administration. Higher bioavailabilities were found after mesenteric venous and intravenous administration (sham-operated rat) due to a decrease in the beta-value (elimination rate constant). The low bioavailability of sulpiride following oral administration was concluded to result, not from metabolism in the liver, but from reduced absorption by the gastrointestinal tract.