DETERMINATION OF ANS-4-ISOPROPYLCYCLOHEXYLCARBONYL)-D-PHENYLALANINE IN HUMAN PLASMA BY SOLID-PHASE EXTRACTION AND COLUMN-SWITCHING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

A column-switching high-performance liquid chromatography method with ultraviolet detection at 210 nm has been developed for the determinati on of ans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine (AY4166, I) i n human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak Light tC(18), followed by HPLC. The calibration graph fo r I was linear in the range 0.1-20 mu g/ml. The limit of quantitation of I, in plasma, was 0.05 mu g/ml. The recovery of spiked I (0.5 mu g/ ml) to drug-free plasma was over 92% and the relative standard deviati on of spiked I (0.5 mu g/ml) compared to drug-free plasma was 4.3% (n = 8).