Abstract: AIM: To study the effect of licorice extract on cyclosporine pharmacokinetics in rats. METHODS: Experimental rats were randomly divided into the control and test groups which were administrated respectively with normal saline and extract of licorice. After pretreated with extract of licorice (0.5 g/kg, once daily) for 7 days, cyclosporine was given to the rats by intragastric administration in the 8th day. Whole blood cyclosporine concentrations were measured by a fluorescence polarization immunoassay (FPIA). Pharmacokinetic parameters between two groups were compared. RESULTS: There were no significant differences between the two groups in the main pharmacokinetic parameters of cyclosporine, such as C_max,t_max,t_{1/ 2},AUC_{0-48 h},AUC_0-∞,MRT,CL/F,V/F(P>0.05). CONCLUSION: The results suggest that treatment with extract of licorice (0.5 g/kg, once daily) for 7 days did not affect the pharmacokinetics of cyclosporine in rats.

Key words: Licorice extract, Cyclosporine, Pharmacokinetics, Interaction