Effect Of Epimedii Folium Extract On The Metabolism Of Tadalafil In Beagles

OBJECTIVE:We developed and validated a novel,sensitive,selective and inexpensive high performance liquid chromatography?HPLC?method for simultaneous determination of tadalafl in beagles plasma,and to investigate the effect of epimedii folium on the metabolism of tadalafl in beagles.METHODS:In this study,we selected three male and three female healthy beagles dogs,weighing about 8 kg.The experiment used self-comparison method.Beagles was given to tadalafl single dose(1 mg·kg^-1)?control group?and then epimedii folium(0.6g·kg^-1)given for 7 days?test group?to observe pharmacokinetic differences by using self-control method.The analytical column was packed with ZORBAX XDB-C18.A mixture of acetonitrile-0.1%trifluoroacetic acid-water?48:10:42??V/V/V?was used as the mobile phase with the flow rate at 1.0 mL·min^-1.The column temperature was set at30.0°C The detection wavelength was set at 286 nm.The tadalafl was extracted by ethyl acetate from plasma at the alkaline condition using carbamazepine as the internal standard.The main pharmacokinetic parameters were calculated by DAS 2.0 software.To observe the effect of epimedium extract on the metabolism of tadalafil.RESULTS:Under the conditions of this experiment,the retention time of tadalafil was 6.41min,and the retention time of internal standard carbamazepine was 5.44 min.The plasma concentrations of tadalafl in the range of 1-200 ng/ml had a good linear relationship.The standard curve of tadalafil y=0.0067x-0.0038,?r=0.999 8?.The lower limit of quantitation was 1 ng/mL.The intraday and intraday precision RSD of low,medium and high concentrations?2.5,50,150 ng/mL?were less than 15%.The relative recovery rate was good.The plasma samples were kept at room temperature for 24 h,freeze-thawed three times and frozen for 30 days.The t_1/2 of tadalafl in experimental group and control group were?9.06±2.08?h and?12.39±5.63?h,C_maxax were?72.59±16.16?ng/mL and?127.16±17.93?ng/mL,AUC_?0-??were?798.63±73.89?ng·h/mL and?1133.91±271.70?ng·h/mL,AUC_?0-t?were?739.34±69.26?ng·h/mL and?980.57±197.58?ng·h/mL,respectively.Results show that the C_max of tadalafil in test group is reduced by 42.91%,the AUC_?0-t?and AUC_?0-??are also reduced by 24.60%and 29.57%respectively,the elimination rate is also increased,and the t_1/2is reduced by 3.33h.In combination with epimedium extract,tadalafil reduced the AUC and half-life of tadalafil,while epimedium extract reduced the exposure of tadalafil.These results suggest that epimedii folium can induce the metabolism of tadalafil.CONCLUSIONS:?1?The established HPLC–DAD method is rapid,sensitive and reliable.It is suitable for the pharmacokinetics of tadalafl and drug-drug interactions.?2?Epimedii Folium can induce the metabolism of tadalafil in vivo,reduce the exposure of tadalafil.