Objective: To develop an LC-MS method to determine berberine and palmatin in rats plasma simultaneously. The method was employed to investigate pharmacokinetics of berberine and palmatin. Method: Blood samples were collected at different time after oral administration of extracts Rhizoma Coptidis

The plasma concentration of berberine and palmatin was determined by LC-MS.Pharmacokinetic parameters were calculated by WinNonlin 5.1 software. Result: The linear range of berberine and palmatin was 5~1 000 ng ·mL(r=9 989)

2.5~500 ng ·mL-1(r=9 994) respectively.The average recovery of berberine and palmatin was exceeded 85％(n=5)

the precision of inner-day and inter-day was less than 15%.The pharmacokinetics parameters calculated by noncompartment model

such as AUC

T1/2

Cmax of berberine were: 707.91 h ·ng ·mL-1

1 220.32 h ·ng-1 ·mL-1

2 424.62 h ·ng-1 ·mL-1; 1.89 h

2.29 h

4.79 h; 315.78 ng ·mL-1

501.58 ng-1 ·mL-1

584.57 ng ·mL-1;Tmax was all 1 h. The pharmacokinetics parameters AUC

T1/2.

Cmax of palmatin were: 130.29 h ·ng-1 ·mL-1、348.61 h ·ng-1 ·mL-1

872.76 h ·ng-1 ·mL-1; 1.71 h

2.64 h

5.89 h;Tmax was all 1 h.The relationship between dose and AUC showed good linearity. Conclusion: The method described in this report has high sensitivity and selectivity

and was suitable for pharmacokinetic studies of berberine and palmatin. The kinetic process of berberine in rats in vivo was fitted to a one-compartment model at low dosage

while it was fitted to two-compartment model at middle and high dosages; the kinetic process of palmatine was all fitted to a one-compartment model.