Pharmacokinetics and bioavailability of ginsenoside Rb1 and Rg1 from Panax notoginseng in rats

Panax notoginseng is used as a therapeutic agent to stop haemorrhages and a tonic to promote health in Chinese medicine. Currently saponins of P. notoginseng (PNS) are especially given attentions for their hemorheological properties. The pharmacokinetic profiles of the main PNS are still not accurately investigated. Therefore, our preliminary aim is to elucidate the pharmacokinetic features of ginsenoside Rb(1) (Rb(1)) and ginsenoside Rg(1) (Rg(1)), two of the main PNS in rats. Firstly, quantitive analysis of Rb(1) and Rg(1) in saponins of P. notoginseng was studied and the most suitable assay method by HPLC for blood sample were established. Then Rb(1) and Rg(1) in the same serum were determined after administering PNS to rats. The decline of Rb(1) in serum could be described by a two-compartment model. The half-life of alpha phase was 23.40 min and that of beta phase was 17.96 h. Rb(1) was absorbed from the digestive tract and the bioavailability via P.O. was 4.35%. The pharmacokinetics of Rg(1) in rats also could be described by a two-compartment model. The half-lives of Rg(1) were 24.23 min for alpha phase and 14.13 h for beta phase. Rg(1) could be absorbed in the digestive tract and the oral bioavailability was 18.40%. Both of the low oral bioavailability of Rb(1) and rapid reduction of Rg(1) in blood indicated that formula modification is necessary.