DETERMINATION OF FELODIPINE CONCENTRATION IN HUMAN PLASMA BY GC-ECD AND STUDY OF ITS PHARMACOKINETICS

A rapid,accurate and sensitive gas chromatographic method using electron-capture detector (GC-ECD) was developed for the determination of felodipine concentration in human plasma. Nimodipine was used as internal standard. The plasma samples were extracted using a mixtrure of ethyl ether and nhexane (2∶1) to give mean recoveries of 97.3% of felodipine. The extracts were separated by a 5% SE-30 glass packed column (2 m×3 mm). The detection limits for felodipine was 0.25 ng·ml^-1. The precisions (RSD%, n=5) of withinday and daytoday were less than 5.09% and 8.62%, respectively. The pharmacokinetic parameters of felodipine in ten men were investigated by this method. The concentrationtime curve was fitted to a twocompartment model. Its main pharmacokinetic parameters were: T_1/2α=0.76 h, T_1/2β=16.09 h,C_max=4.78 ng·ml^-1,T_max=2.01 h, AUC=45.2 h·ng·ml^-1.