Comparative pharmacokinetic study of paeoniflorin after oral administration of pure paeoniflorin, extract of Cortex Moutan and Shuang-Dan prescription to rats.

Shuang-Dan (SD) is a traditional Chinese prescription containing Cortex Moutan and Radix Salviae miltiorrhizae and commonly used for treating cardiovascular disease. Paeoniflorin is a main effective ingredient of Cortex Moutan and the pharmacokinetic differences of paeoniflorin following oral administration of pure paeoniflorin, Cortex Moutan extract and SD decoction to rats were studied with approximately the same dose of 30mg/kg paeoniflorin. At different time points (5, 10, 15, 30, 45, 60, 90, 120, 150, 210, 270, 360, 450min), plasma concentration of paeoniflorin was determined using a simple and rapid HPLC-MS method. Unpaired student's t-test was used for the statistical comparison. A bimodal phenomenon was observed in the plasma profile after oral administration of Cortex Moutan extract. Statistically significant increase (P<0.05) in pharmacokinetic parameters of paeoniflorin including AUC(0-t), AUC(0-infinity) and MRT were obtained after oral administration of Cortex Moutan or SD decoction comparing with pure paeoniflorin. The investigation showed that among all calculated parameters, AUC(0-t), AUC(0-infinity), MRT, k(e) and T(1/2), there were no significant differences between the two decoctions. The results indicated that the reason which delay the elimination of paeoniflorin and enhance its bioavailability might be some ingredients in Cortex Moutan extract.