Biliary contrast agents: comparative study about the binding to human plasma and the effect of human plasma on hepatic uptake.

The binding of one oral and five intravenous biliary contrast agents to human plasma was determined by equilibrium dialysis. Large differences of the binding strength were found. The presence of human plasma in the incubation medium largely inhibited the rate of the uptake of the six drugs by rat livers slices. A positive linear correlation between the extent of the plasma protein binding and the inhibition of the hepatic uptake could be demonstrated for the six biliary contrast agents investigated.