DETERMINATION OF ZAFIRLUKAST, A SELECTIVE LEUKOTRIENE ANTAGONIST, HUMAN PLASMA BY NORMAL-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

A high-performance liquid chromatographic (HPLC) method was developed for the determination of zafirlukast, a selective peptide leukotriene receptor antagonist, in human plasma. Zafirlukast and the internal sta ndard, ICI 198 707, were extracted from deproteinated plasma samples u sing large reservoir C-18 solid-phase extraction columns and analyzed by normal-phase liquid chromatography with fluorescence detection. The method had a lower limit of quantitation of 0.75 ng/ml and a linear c alibration curve in the range of 0.75 to 200 ng/ml. The absolute recov ery of zafirlukast was >90%, and the within-day and between-day relati ve standard deviations were <9%. The utility of the method in the char acterization of the plasma concentration-time profiles of zafirlukast in clinical studies was demonstrated. (C) 1997 Elsevier Science B.V.