Objective:To investigate the pharmacokinetic properties of cimicifugoside H-2 in rats

and the absolute bioavailability of cimicifugoside H-2 in vivo were also scarcely reported. Method: SD rats were administrated an intravenous dose of cimicifugoside H-2 (5 mg·kg-1) and oral dose of cimicifugoside H-2 (5 mg·kg-1) or Cimicifuga foetida extract (50 mg·kg)

respectively. At different time points

the concentrations of cimicifugoside H-2 in rat plasma were determined by LC-MS-MS method. Main pharmacokinetics parameters were estimated by non-compartmental analysis using the DAS 2.0 software. Result: The curves showed excellent linear regressions within the range of tested concentrations. The intra-and inter-day variations were below 11% in terms of RSD. The recoveries were 87.0%-91.6% for spiked cimicifugoside H-2 samples. The PK parameters after iv administration of individual cimicifugoside were respectively: elimination half-life 1.03 h-1; clearance 691 mL·h-1·kg-1. PK parameters following oral administration of the extract and cimicifugoside H-2 was respectively: Tmax 0.5 and 4.0 h. Absolute oral bioavailability (F) was 21.2% and 36.7%. Conclusion: This method proved to be specific

accurate and sensitive to be applied to the pharmacokinetics studies of H-2 in rats. Comparison of the pharmacokinetics of cimicifugoside H-2 given alone and together in rat suggest that administration of herbal preparations of Cimicifuga for clinical use may provide longer duration of action than administration of single isomers.