Comparative pharmacokinetic study of paeoniflorin after oral administration of decoction of Radix Paeoniae Rubra and Radix Paeoniae Alba in rats

An investigation was designed and conducted to compare the pharmacokinetics difference of paeoniflorin after oral administration of the extracts of Radix Paeoniae Rubra and Radix Paeoniae Alba to rats on separate occasions. Quantification of paeoniflorin in rat plasma was achieved using a simple and rapid HPLC method for pharmacokinetic study. After oral administration of decoctions of Radix Paeoniae Rubra and Radix Paeoniae Alba, paeoniflorin was absorbed and reached a maximum concentration of 3.69 ± 1.46 and 1.46 ± 0.29 (p < 0.05) μg/ml at 1.67 ± 0.43 and 0.80 ± 0.35 h (p < 0.05), respectively. Compared to the AUC (18.85 ± 7.54 μg h/ml) after oral administration of the paeoniflorin solution, a smaller AUC (10.61 ± 1.51 μg h/ml, p < 0.05) and a larger AUC (24.89 ± 7.41 μg h/ml) of paeoniflorin after oral administration of the decoctions of Radix Paeoniae Alba and Radix Paeoniae Rubra were obtained, respectively. There were statistically significant differences in pharmacokinetic parameters of paeoniflorin including the t_max, C_max, AUC, t_1/2, CL, and V_d among the animals orally administered the decoctions of Radix Paeoniae Rubra and Radix Paeoniae Alba. In particular, the parameters of t_max, C_max, and AUC of paeoniflorin were remarkably increased (P < 0.05, P < 0.001) when oral administering paeoniflorin in the decoctions of Radix Paeoniae Rubra, but t_1/2, V_d, and CL were decreased (P < 0.05 or P < 0.01), in comparison of the decoction of Radix Paeoniae Alba.