Biliary Excretion Rate of Semisynthetic Rifamycins in the Rat

Abstract

Biliary excretion of 39 semisynthetic rifamycins was studied after intravenous administration to rats. For amides and hydrazides of rifamycin B, biliary excretion rate was inversely proportional to the number of carbon atoms on the nitrogen atoms. A decrease of biliary excretion rate was accompanied by increase of acute toxicity in mice. Most of these compounds decrease bile production. The low biliary excretion of N,N-disubstituted amino-methylderivatives of rifamycin SV was correlated with low water solubility. Dimethyl- and diethyl-hydrazone derivatives had the lowest biliary excretion rate. The results are discussed in view of further evaluation of some compounds.