Pharmacokinetics of paeoniflorin after oral administration of Shao-yao Gan-chao Tang in mice.

Paeoniflorin, a monoterpene glycoside, is the principal bioactive component of Paeoniae Radix. The traditional prescription Shao-yao Gan-chao Tang (SGT; Kampo: Shakuyaku-Kanzo-To), which is composed of Paeoniae Radix and Glycyrrhizae Radix, has been widely used in China and Japan. Quantification of paeoniflorin in mouse plasma after oral administration of SGT (at a dose containing 10 mg/kg paeoniflorin) was achieved using a simple and rapid high-performance liquid chromatography method. The plasma concentration-time curves were fitted with mean terminal half-lives (t 1/2) of 116.17 min. The maximum plasma concentration (Cmax) of paeoniflorin was 111.56 ng/ml, time to reach maximum concentration (tmax) was 17.00 min, the area under the plasma concentration-time curve (AUC)0-t was 12293.42 ng x min/ml, clearance/bioavailability (CL/F) value was 644.74 ml/min x kg, apparent volume of distribution/ bioavailability (Vd/F) value was 103.05 l/kg, and the mean residence time (MRT) was 169.64 min. These results, together with the previously reported kinetic data of paeoniflorin after oral administration of Paeoniae Radix extract alone, indicated that absorption of paeoniflorin after oral administration of SGT was significantly greater than that after oral administration of Paeoniae Radix alone.