Effects Of Simvastatin And Dextromethorphan On Pharmacokinetics Of Apatinib In Rats

Apatinib,simvastatin and dextromethorphan are commonly used in the treatment of advanced gastric cancer,cardiac-cerebral vascular diseases and respiratory system diseases.Acording to the report,more than 90% of apatinib was metabolized by CYP3A4 and CYP2D6 enzymes.Moreover,simvastatin and dextromethorphan were CYP3A4 and CYP2D6 enzyme sbustrate respectively,apatinib may compete with both drugs for the same metabolic enzymes.This experiment through the establishment of liquid chromatography tandem spectrometry(LC-MS/MS)determination plasma concentration of apatinib in rats,a preliminary investigation of simvastatin and dextromethorphan for it in rats for pharmacokinetic effects of apatinib,so as to provide reference for clinical rational drug use.Part one Determination of plasma concentration of apatinib in rats by LC-MS/MSObjective:To establish an accurate,efficient and rapid LC-MS/MS to determine plasma concentration of apatinib in rats.Method:Ion source:ESI;Ion mode:MRM;Detection mode:positive ions;Apatinib quantitative ion pair: 398.2/211.9m/z,internal standard tinidazole quantitative ion pair: 248.0/121.1m/z.Column: kinetex C18(2.1×100 mm,2.6μm);The mobile phase: 0.1% formic acid 10 m M ammonium acetate aqueous(A)-0.1% formic acid methanol(B);Flow rate: 0.2ml·min-1;The elution conditions: 0.01-0.5min,70%B,0.2ml·min-1;0.5-1.5min,70%B,0.2-0.4ml·min-1;1.5-2.5min,70%B,0.4ml·min-1;2.5-2.6min,70%B,0.4-0.2ml·min-1;2.6-3.5min,70%B,0.2ml·min-1.Tinidazole was used as internal standard,plasma samples of rat were precipitated by acetonitrile,vortex and centrifugation,injection volume was 3μl.Results: The concentration range of apatinib was 5ng/ml-1000ng/ml,r=0.9994.The intra-day RSD% and inter-day RSD% of apatinib were in the range of 1.90%-6.97%,the extraction recoveries were in the range of95%-106%,and the matrix effect were in the range of 92%-102%.All results of the methodology were in accordance with the requirements of the guidelines for the analysis of biological samples in Chinese Pharmacopoeia.Part two Effects of simvastatin and dextromethorphan on pharmacokinetics of apatinib in ratsObjective: To evaluate the effect of simvastatin and dextromethorphan on apatinib metabolism through pharmacokinetic method,which could provide reference for rational clinical use of apatinib.Method: 30 male SD rats were randomly divided into 3 groups,the control group(apatinib alone group),the group A(simvastatin+apatinib combination group)and group B(dextromethorphan+apatinib combination group).0.5ml of blood were taken from the rat inner canthus at 0.25,0.5,1,1.5,2,3,4,6,8,12,24,48 h after oral administration.DAS 3.0 software was used to calculate pharmacokinetic parameters of apatinib,taking non compartmental model.SPSS 21.0 software was used to analyse the pharmacokinetic parameters,and compare the influence of simvastatin and dextromethorphan respectively to apatinib pharmacokinetics.Results:1.Compared with control group,non compartmental model parameters of MRT(0-t),MRT(0-∞),AUC(0-t),AUC(0-∞),Vz/F,CLz/F,Cmax in group A were statistically significant difference(P<0.05),while Lambda_z,t1/2z,Tmax and C_last were not statistically significant.2.Compared with control group,non compartmental model parameters of MRT(0-t),MRT(0-∞),AUC(0-t),AUC(0-∞),Lambda_z,t1/2z,Vz/F,CLz/F,Cmax in group B were not statistically significant,while C_last and Tmax two goups were statistically significant difference(P<0.05).Conclutions:1.The LC-MS/MS method established in this study is simple,efficient and accurate for determining the plasma concention of apatinib,and the results of the methodology are in accordance with the validation gulidelines of biological sample quantitative analysis.2.The results showed that simvastatin signifiantly affected main pharmacokinetic parameters of apatinib in rats,such as AUC,MRT,Vz/F,CLz/F and Cmax.As a result,the plasma exposure of apatinib in rats decreased significantly,the clearance rate and apparent distribution volume increased significantly.However,dextromethorphan had a certain effect on the C_last and Tmax of apatinib in rats and had no significant effect on other parameters.Thy study indicated that in the clinical practice,apatinib combined with simvastatin needs to adjust the dose and when combined with dextromethorphan,there is no need to adjust the dose.