Determination and pharmacokinetic study of nodakenin in rat plasma by RP-HPLC method.

A simple, sensitive and selective RP-HPLC method has been developed for quantification of nodakenin in rat plasma. Nodakenin in rat plasma was extracted with acetonitrile, which also acted as a deproteinization agent. Chromatographic separation of nodakenin was performed on an analytical Diamonsil ODS C18 column, with a mobile phase of MeOH-H2O (1:1, v/v) at a flow-rate of 1.0 mL/min, and UV detection was set at 330 nm. The calibration curve was linear over the range 0.2-12.0 microg/mL (R2 = 0.9995) in rat plasma. The lower limit of detection and quantification were 0.01 and 0.1 microg/mL, respectively, using the rat plasma sample. The extraction recoveries were 77.36 +/- 4.56, 82.89 +/- 1.84 and 81.66 +/- 2.49% at concentrations of 1.0, 5.0 and 10.0 microg/mL, respectively. The intra- and inter-day precision and accuracy were validated by relative standard deviation and relative error, which were in the ranges 5.07-5.83 and 3.95-6.29%, respectively. After i.v. administration to rats at a single dose of 40 mg/kg, the plasma concentration-time curve of nodakenin was best conformed to a two-compartment open model. This assay method has been successfully applied to the study of the pharmacokinetics of nodakenin in rats.