Kinetics of R andS warfarin enantiomers.

A method is reported for simultaneous measurement of the kinetics of R and S warfarin enantiomers. Pure pentadeuterated R and S enantiomers were each combined with unlabeled enatiomers to form "pseudo"-racemic mixtures which were given (0.75 mg/kg) to 5 healthy subjects. Plasma R and S enantiomer levels were measured by gas chromatography--mass spectrometry. Elimination half-lifes (t1/2S) and volumes of distribution (VdS) of the enantiomers were not altered by the presence of the other.