An HPLC method for the determination of isovitexin in rat plasma and different tissues was developed.The separation was achieved on a C_（18）column with a mobile phase consisting of methanol-1% acetum（40：60,v/v）at a detection wavelength of 338 nm and a column temperature of 30℃.Rutin was chosen as the internal standard.The linear range of the standard curves was 0.20-128.75μg/mL in the plasma and 0.024-3.09μg/mL in the tissues.The LOQ was 0.19μg/mL in the plasma and 0.024μg/mL in the tissues.The relative recoveries of isovitexin ranged from 93% to 105% in the plasma and 87% to 112% in the tissues.The intra-and inter-day precisions were all below 8%.The pharmacokinetics and tissue distribution of isovitexin in rats were studied with the method.Blood samples were collected at fixed time intervals after the i.v.injection of isovitexin at a dosage of 18.75,3.75 and 0.75 mg/kg;the tissue samples（brain,liver,kidney,heart,lung,spleen and ovary）were obtained at 10,30,and 60 min after the i.v.injection of isovitexin at a dosage of 18.75 mg/kg.The pharmacokinetics of the isovitexin in three different dosages in the rats fit the two-compartment open model.The isovitexin displayed linear dynamics in the dosage range of 0.75-18.75 mg/kg.The mean value of t_（1/2α）was 1.54-1.84 min,and t_（1/2β）was 36.94-46.27 min at the three dosages.The tissue distribution study showed that the sequence of tissue drug concentration from high to low was kidneyliverlung≈ovaryheart≈spleenbrain.
