An HPLC method for the determination of isovitexin in rat plasma and different tissues was developed. The separation was achieved on a C18 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 °C. Rutin was chosen as the internal standard. The linear range of the standard curves was 0.20-128.75 μg/mL in the plasma and 0.024-3.09 μg/mL in the tissues. The LOQ was 0.19 μg/mL in the plasma and 0.024 μg/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 t1/2α was 1.54-1.84 min, and t1/2β 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 kidney > liver > lung ≈ ovary > heart ≈ spleen > brain.
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