Phenobarbital-enhanced biliary excretion of administered unconjugated and conjugated sulfobromophthalein (BSP) in the rat

Abstract

Phenobarbital pretreatment resulted in increases in the maximal rates of biliary excretion of intravenously administered sulfobromophthalein (BSP) and BSP-glutathione. In rats given unconjugated BSP, the rise in excretion was due to an increase in the amount of conjugated dye delivered into bile. These results provide evidence for at least two sites of action of phenobarbital in enhancing maximal rates of BSP excretion into bile: (1) increased transport of conjugated dye from liver cells into bile, and (2) increased intrahepatic metabolism of dye.