OBJECTIVE:To study the pharmacokinetics effects of naloxone combination on Shenmai injection in rats in vivo. METHODS:12 rats were randomly divided into monotherapy group (Shenmai injection 9.00 ml/kg,iv) and combination group (Shenmai injection 9.00 ml/kg+naloxone 1.80 ml/kg,iv). The blood samples were collected before administration and 0.083,0.25, 0.5,0.75,1,1.5,2,3,6,12,24,48,96 and 144 h after administration. HPLC was adopted to determine the plasma concentra-tions of ginsenosides Rg1,Re and Rb1,and DAS 2.0 software was used to calculate the pharmacokinetic parameters. RESULTS:Compared with monotherapy group,the plasma concentration of ginsenosides Rg1 in combination group was increased,CL was de-creased,t1/2 and MRT were prolonged,and AUC0-144 h was increased;the plasma concentration of ginsenosides Re was increased,Ke was decreased,t1/2 was prolonged,MRT was shortened,and AUC0-144 h was increased;the plasma concentration of ginsenosides Rb1 was decreased,Ke was increased,t1/2 and MRT were shortened,and AUC0-144 h was decreased,with significant differences(P<0.01 or P<0.05). CONCLUSIONS:Shenmai injection combined with naloxone can slow down the removing of ginsenosides Rg1 and Re in vivo,and obviously the plasma concentration of Shenmai injection is higher than monotherapy group;speed up the removing of ginsenosides Rb1,and the plasma concentration of Shenmai injection is lower than monotherapy group obviously.