Abstract
Dependence of biliary excretion behavior of a quaternary ammonium compound on administration route was reported. When valethamate bromide or scopolamine-N-butyl bromide was infused through portal vein at a constant rate, it produced a higher biliary excretion rate and total excreted amount than when they were infused through femoral vein at the same rate. This phenomenon was discussed to estimate the availability of an absorbed drug from a small intestine with biliary excretion data when the excretion data of the intravenously administered drug was taken as the standard which corresponded to the complete absorption. That is, if the dependence is overlooked, the estimated availability from biliary excretion data would be overestimated, because a drug through portal vein was more excretable than that through femoral vein.
