Stereoselective toxicokinetics and tissue distribution of ethofumesate in rabbits

The stereoselective toxicokinetics of ethofumesate enantiomers following a single intravenous (i.v.) administration at doses of 30 mg/kg were investigated in rabbits. Plasma concentrations of (+)‐ and (−)‐ethofumesate were analyzed by a validated chiral HPLC method that involved extraction of plasma with organic solvent followed by separation on a cellulose‐Tris‐(3,5‐dimethylphenylcarbamate)‐based chiral column and quantification by UV absorbance at 230 nm. Plasma concentration‐time curves after i.v. administration were best described by an open two‐compartment model. The concentration of the (−)‐enantiomer decreased more rapidly than that of the (+)‐enantiomer. Significant differences in toxicokinetic parameters between the two enantiomers indicated that stereoselective behavior occurred with the (−)‐enantiomer being preferentially metabolized and eliminated. Chirality 19:632–637, 2007 © 2007 Wiley‐Liss, Inc.