Validation of an HPLC method for the determination of scutellarin in rat plasma and its pharmacokinetics

A validated HPLC method was developed for the quantification of scutellarin in rat plasma using a liquid-liquid extraction and an ultraviolet detection. Chromatographic separation of scutellarin in plasma was performed on a C18 column, with a mobile phase of acetonitrile-water (23:77, v/v), adjusted to pH 2.5 with 1M phosphoric acid, and rutin was used as an internal standard. The calibration curve was linear over the range 0.1-100 microg/ml in rat plasma. The average extraction recoveries were 85.9+/-8.9, 71.0+/-4.6, 72.7+/-1.2% (n=3) at concentrations of 0.1, 2, 100 microg/ml, respectively, and the within-day and between-day precisions were less than 15%. After intravenous administration to rats over the doses range of 10-40 mg/kg, the plasma concentration-time curve of scutellarin was best conformed to three-compartment open model. The AUC of scutellarin was proportional to dose, and the systemic clearance (Cl), elimination half-life (t1/2beta) and apparent volume of distribution (Vc) were not significantly different among the three doses, suggestive of the linear pharmacokinetics characteristic of scutellarin after intravenous administration.