Pharmacokinetics of guanfu base I, an active metabolite of guanfu base A, in rats

A liquid chromatographic-mass spectrometric (LC-MS) method was developed and validated for determination of guanfu base I (GFI), and the pharmacokinetics of GFI in Sprague-Dawley rats was examined. The method was linear in the 0.05-20 mug/ml concentration range (r=0.9994). The recovery of guanfu base I was more than 80%. The intraday and interday precision, expressed as the relative standard deviation (RSD), was generally good (<15%). After i.v. dosing, plasma GFI concentration declined in a bi-phasic manner with a terminal elimination half-life of 2.49 h. The total plasma clearance values was 1.46 l/h/kg. After oral dosing, the plasma GFI concentration reached a maximum within 0.5 h. The absolute bioavailability of GFI was 71.31%.