Effects of Aikeqing on Drug-Metabolizing Enzyme Activity and on Pharmacokinetic Parameters of Lopinavir and Ritonavir in Rat Plasma
Objective To investigate the effects of Aikeqing(AKQ),a compound of Chinese medicine,on drug-metabolizing activity and on the pharmacokinetic parameters of HIV-1 protease inhibitors lopinavir(LPV)and ritonavir(RTV)in Kaletra tablets.Methods Human liver microsomes were co-incubated with mixed probes and AKQ.HPLC-MS was employed to measure the content of probe.Half-inhibitory concentration(IC50)of AKQ on different subtypes of cytochrome P450 enzymes involved in drug metabolism of liver microsomes was calculated.The P450 subtype,whose activity was significantly inhibited by AKQ was then identified.HPLC-MS analytical method for simultaneous determination of LPV and RTV in rat plasma was established.SD rats were orally given AKQ or vehicle once a day for 7 consecutive days.After half an hour of the last gavage of AKQ,the rats were given Kaletra by intragastric administration.Then,the blood concentration of LPV and RTV were measured and the effect of AKQ on pharmacokinetic parameters of LPV and RTV were analyzed.Results The methanol extract of AKQ at the concentrations of 0～500 µg·mL-1 showed inhibitory effects on the metabolic activity of CYP2D6,CYP2C8、CYP2E1,CYP2C19,CYP1A2,CYP2B6,CYP2C9 and CYP3A4,with IC50 values of 7.7,75.3,144.0,99.5,43.5,104.5,49.3 and 204.9 µg·mL-1,respectively.An HPLC-MS/MS method was established for simultaneous quantification of LPV and RTV in blood samples.LPV and RTV showed linear relationships in the ranges of 30～10 000 ng·mL-1 and 3～1 000 ng·mL-1,respectively.The lowest limits of quantification were 30 ng·mL-1 and 3 ng·mL-1.Intra-day and inter-day precision were all less than 5%,and the accuracy of LPV and RTV was in the range of 96.3%～109%.The extraction recovery rates were not less than 88.7%,the matrix effects were 93.8%～105.0%,and the plasma samples were stable.Compared with Kaletra group,there was no significant changes in non-compartmental model parameters including AUC0-t,AUC0-∞,MRT0-t,t1/2z,tmax,Vz/F,Clz/F and Cmax of LPV in AKQ+Kaletra group(P＞0.05).But MRT0-∞ was found to be obviously affected by AKQ(P＜0.05).All pharmacokinetic parameters of RTV showed no significant change in AKQ+Kaletra group(P＞0.05).Conclusion Aikeqing exhibited varying degrees of inhibitory effects on 8 human drug-metabolizing cytochromes P450,especially CYP2D6.A human-equivalent dose of Aikeqing does not affect the pharmacokinetic parameters of lopinavir and ritonavir in rats.
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