Comparative pharmacokinetics of icariin in plasma after oral administration of Er-Xian decoction or pure icariin in rats

The present study was to investigate the pharmacokinetics of icariin in rat after oral administration of single dose of Er-xian decoction (EXD) and pure icariin. Blood samples were collected by orbital vein at time intervals after drug administration and the plasma concentrations of the studied components were determined by high performance liquid chromatography (HPLC) after the plasma protein was precipitated directly with acetonitrile. Icariin was successfully separated using a C-18 column with a UV detection at 270 nm and a mobile phase of acetonitrile-water with 0.1% H3PO4 (35:65, v/v) pumped at 1.0 ml/min. The method had a lower limit of quantitation (LOQ) of 0.60 mu g/ml for icariin with the limit of detection (LOD) 0.35 mu g/ml, based on a signal-to-noise ratio of 3. The assay was linear over a range 0.667 to 42.67 mu g/ml with coefficient of determination greater than 0.99 for analytes. The extraction recoveries was > 80%. The method has shown tremendous reproducibility, with intra-and inter-day precision < 4.9% (RSD), and has proved to be highly reliable for the analysis of plasma samples. The main pharmacokinetic parameters of icariin in rats after administration, EXD and icariin were processed by Das 2.0, while calculating the pharmacokinetic parameters of one compartment model. From the experimental results, the method had been applied successfully to pharmacokinetics of icariin in rat plasma after oral administration of pure icariin or EXD.