RESUMO
Within 24 h, 50% of a single dose of the acenocoumarol enantiomers was recovered in bile and 20% in urine of Wistar rats. The elimination products were mainly (greater than 90%) the 6- and 7-hydroxyacenocoumarol as conjugates in the bile but free in the urine. Only R-acenocoumarol, free and conjugated, was excreted in bile. There were no gross differences between the enantiomers in metabolic pattern or in the amount of metabolites formed. A significant difference was observed for the biliary excretion of the 7-hydroxy metabolite; the ratio of free and conjugated 7-hydroxyacenocoumarol was three times higher for the S- than for the R-isomer. An unknown third metabolite was recovered in bile in higher amounts with the S- than with the R-acenocoumarol. Only traces of this metabolite were recovered from urine. The data show an extensive biliary excretion of acenocoumarol and demonstrate stereoselective mechanisms in the excretion processes.
Assuntos
Acenocumarol/metabolismo , Bile/metabolismo , Acenocumarol/urina , Animais , Fenômenos Químicos , Físico-Química , Cromatografia Líquida de Alta Pressão , Conformação Molecular , Ratos , EstereoisomerismoRESUMO
Acenocoumarol, to which a 14C-labeled internal standard has been added, is extracted at pH 4 into ethyl acetate-heptane (20:80 v/v), back-extracted into aqueous sodium hydroxide solution after solvent washing with a pH 7 buffer, and reextracted after acidification in the solvent mixture. It is then acetylated with 3H-acetic anhydride. The acenocoumarol acetyl derivative is separated from the metabolite derivatives by TLC, and its radioactivity is measured. The method is specific and sensitive to a concentration of 8 ng/ml.
