[Determination of guanfu base A hydrochloride in plasma by LC-MS method and its pharmacokinetics in dogs].

AIM: To establish an analytical method for determination of guanfu base A (GFA) concentration in plasma and to study its pharmacokinetic profile in dogs. METHODS: Six dogs were given a 7.56 mg.kg-1 dose intravenously. Blood samples were collected at various time-points after drug administration. Analytical method based on liquid chromatography-mass spectrometry (LC-MS) was established to determine the plasma concentration of GFA. Pharmacokinetic evaluation was carried out using the 3P87 program. RESULTS: The calibration curves were linear over the concentration range from 0.42 microgram.mL-1 to 21.2 micrograms.mL-1 (gamma = 0.9994). The intra-day and inter-day precisions were generally good (< 15%) at low, medium and high concentrations. The overall recovery of the analytes was more than 80%. Six dogs were given an i.v. dose of 7.56 mg.kg-1 of GFA hydrochloride, an open three compartment model best described the concentration-time profiles for GFA. The half-lives for the rapid and slow distribution phase and terminal elimination phase (T1/2 pi, T1/2 alpha and T1/2 beta) were 0.07 h, 1.5 h, and 13.5 h, respectively. The total area under the plasma concentration-time curve (AUC), the volume of the central compartment (Vc), and plasma clearance (CLs) were 61.43 micrograms.h.mL-1, 0.37 L.kg-1 and 0.14 L.kg-1.h-1, respectively. CONCLUSION: The analytical method was shown to be sensitive, specific, rapid and reproducible, and was suitable for pharmacokinetic studies of GFA.