Pharmacokinetic study of Guanfu base G in rats by LC-ESI-MS.

A sensitive and simple liquid chromatography -: electrospray ionization mass spectrometry method has been established and validated for the quantification of Guanfu base G in rats. Phenoprolamine hydrochloride was selected as the internal standard. Sample preparation involved simple liquid-liquid extraction by ethylacetate with high efficiency. The chromatographical separation was performed on a Shimadzu C18 column (150 × 2.0 mm, 5 µm) with a gradient elution of 0.2% acetic acid-acetonitrile (30:70, v/v). The method was sensitive with the lowest limit of detection at 1 ng/mL (S/N ≥ 3) in 100 µL of rat plasma. Good linearity (r = 0.9996) was obtained covering a concentration of 5-2000 ng/mL. The intra- and interday assay precision ranged from 4.3 to 6.1% and 5.4 to 8.3%, respectively. In addition, the stability, extraction recovery and matrix effect involved in the method were also validated. After intravenous dosing, rat plasma Guangfu base G (GFG) concentration declined in a biphasic manner with a terminal elimination half-life of 3.72 h. The total plasma clearance values were 1.15 L/h/kg. After oral dosing, the plasma GFG concentration reached a maximum within 0.5 h. The absolute bioavailability of GFG was 83.06%.