Objective: To research change of the content of alkaloids of Ephedrae Herba in plasma after oral administration of different compatibility proportion of drug pair of Ephedrae Herba-Glycyrrhizae Radix et Rhizoma aqueous extracts in rats. Method: Rats were randomly divide into Mahuang (MH) group

MH-GC (12 : 3) group

MH-GC (12 : 6) group and MH-GC (12 : 12) group by weight

plasma samples were collected at different time after drug administration.Plasma samples were treated with liquid-liquid extraction

with amantadine as internal standard

concentrations of norephedrine hydrochloride (NME)

norpseudoephedrine hydrochloride (NMP)

ephedrine hydrochloride (E)

pseudoephedrine hydrochloride (PE)

methylephedrine hydrochloride (ME) in plasma samples at different time were determined by UPLC-MS/MS

DAS 3.0 software was used to calculate pharmacokinetic parameters. Result: Compared with MH group

MRT0-t of NME and NMP were significantly reduced in MH-GC (12 : 3) group

t1/2z and Vz/F of PE had the same trend;AUC0-t of NME

E and PE were significantly increased

CLz/F and Vz/F of PE were significantly reduced in MH-GC (12 : 6) group;MRT0-t of E and PE were significantly extended

CLz/F of ME were significantly increased in MH-GC (12 : 12) group. Conclusion: After compatibility with Glycyrrhizae Radix et Rhizoma

mian pharmacokinetic parameters of five alkaloids in Ephedrae Herba have significant differences.And follow the amount of Glycyrrhizae Radix et Rhizoma

focus of attenuated or efficiency is different.This study demonstrates rationality of ancient prescriptions from pharmacokinetics.