Determination of forsythiaside in rat plasma by high-performance liquid chromatography and its application to pharmacokinetic studies.

A simple high-performance liquid chromatographic method was developed to study the pharmacokinetics of forsythiaside in rat plasma after intravenous administration. Hesperidin was used as the internal standard. The drugs were separated on a reversed-phase C(18) column and detected at 332 nm. Good linearity was achieved in the range of 0.067-26.667 microg/mL. The intra- and inter-assay variation coefficients for this analysis were no more than 10.94 and 14.56%, respectively. The average recovery for forsythiaside was 87.42% from plasma. The analytical sensitivity and accuracy of this assay were adequate for characterization of the pharmacokinetics of intravenous administration of forsythiaside to rats and the assay has been successfully applied to provide pharmacokinetic data. The mean t(1/2Z) was 20.36, 19.40 and 23.62 min for 2, 5 and 20 mg/kg for forsythiaside after i.v. administration, respectively. The AUC(0-t) increased linearly from 40.64 to 624.14 microg min/mL after administration of the three doses.