Résumé
AIM: To establish a sensitive method for quantitative determination of astragaloside Ⅳ (AGS-Ⅳ) in plasma and a preliminary evaluation of its pharmacokinetics parameters in intact rats. METHODS: A liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) was applied for determining AGS-Ⅳ in plasma by using digoxin as the internal standard (I.S.). Six rats were given AGS-Ⅳ 2.0 mg/kg by intravenous infusion for 5 min. Blood samples were drawn intermittently with each intact rat from left femoral artery at 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2, 4, 6, 10, 14 and 24 h after medication. The samples were prepared by solid phase extraction and analyzed through a triple quadrupole mass spectrometer equipped with an electrospary probe. The samples were monitored in selected ion recording (SIR) mode of positive ions by using target ions at m/z 807.5 for AS- Ⅳand at m/z 803.5 for I.S. RESULTS: Calibration curves were linear over the ranges 1-1 000 ng/mL for AGS-Ⅳ (r=0.9992). The intra-and inter-day assay variability values were less than 6% and 8%, respectively. Extraction recoveries from plasma were 92.8%-98.4% for AGS-Ⅳ and 80.0%-90.9% for digoxin, respectively. The lower limit of quantitation (LLOQ) for AGS-Ⅳ was 0.5 ng/mL. The concentration-time curves of AGS-Ⅳ for each rat were fitted to an open two-compartment model by CAPP program. The pharmacokinetics parameters of AGS-Ⅳ were as following: the elimination half-life (t1/2β), clearance rate (CL), distribution volume at steady state (Vss), and AUC0-∞ were (3.46±0.52) h, (0.47±0.02) L/h, (0.76±0.16) L/kg and (4.27±0.19) μg·mL-1·h, respectively. CONCLUSION: These results show that this method is satisfied for the measurements of pharmacokinetics study for AGS-Ⅳ.