Objective:To study the pharmacokinetics of puerarin (PUE) in Gegen Qinlian Decoction (葛根芩连汤,GQD),and the effects of PUE dosage variations on the pharmacokinetics of baicalin (BAL) in mice.Methods:GQD is composed of the concentrated granules of four Chinese herbs.Three dosages with different levels of PUE,including GQD,GQD co-administered with PUE,and GQD co-administration with two times the amount of PUE,were used to research the pharmacokinetics of PUE and BAL in mice.The indirect competitive enzyme-linked immunosorbent assay (icELISA) methods based on an anti PUE-monoclonal antibody (MAb) and BAL-MAb were employed to determine the concentration of PUE and BAL in mice blood.Results:After the co-administration of GQD with PUE,the area under the curves (AUC0-14h) of PUE increased 2.8 times compared with GQD.At the dose of GQD co-administration at two times that of PUE,the AUC0-14h of PUE was almost equal to that of GQD co-administration of PUE,showing non-linear pharmacokinetics.The AUC0-48h of BAL showed a good dose-related increase of PUE (r=0.993) in the range from 100 to 300 mg/kg,indicating that PUE dramatically affects the absorption of BAL in mice.There was no significant difference in the other pharmacokinetic parameters,such as the first time of maximum concentration (Tmax),the second Tmax,or the mean residence time.Conclusions:The icELISA methods were successfully applied to pharmacokinetic studies of PUE and BAL in GQD in mice.The dosage variability of PUE of the main ingredient in GQD affects its own pharmacokinetic characteristics and the absorption characteristics of BAL.