HIGHLY SENSITIVE AND SPECIFIC HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHICANALYSIS OF 7-HYDROXYWARFARIN, A MARKER FOR HUMAN CYTOCHROME P-4502C9ACTIVITY

The formation of 7-hydroxywarfarin in incubations of (S)-warfarin with human liver microsomes reflects their cytochrome P-4502C9 activity. T his paper describes a rapid high-performance liquid chromatographic me thod for the determination of 7-hydroxywarfarin with high sensitivity, selectivity, and a simple sample clean-up procedure. Separation was a chieved with a C-18 reversed-phase column and quantification by fluoro metric defection. The method employs an internal standard resulting in good accuracy and precision. The limit of detection is 150 fmol for 7 -hydroxywarfarin.