Aim:This study consisted of 2 phases:development of a liquid chromatography-tandem mass/mass spectrometry (LC-MS/MS) method for the determination of Ipriflavone in human plasma and the effect of food intake on the pharmacokinetic profiles of ipriflavone in Chinese adult male volunteers.Methods:An analytic method of LC-MS/MS for determination of ipriflavone in human plasma was developed and applied to this pharmacokinetic study.20 healthy Chinese male volunteers were randomized to 2 groups to receive a single dose of 200mg of Ipriflavone under the feed and fasted conditions,respectively.The sequential blood samples were obtained and analyzed from 0 to 48 hour after drug administration.The main pharmacokinetic parameters included Cmax,Tmax,AUC,t1/2,MRT and F were calculated and analyzed to investigate the effect of food intake on the pharmacokinetics of ipriflavone.Results:For this developed LC-MS/MS method,online-disposal was performed and the plasma samples were injected into LC-MS/MS system directly after centrifugalization without any other sample preparation.The Calibration curve was linear over the range of 0.1-50.0 ng/mL.The lower limit of quantification (LLOQ) was 0.1ng/mL.The absolute recoveries of 3 concentration levels were all over 92%.After single dose oral administration,the main different pharmacokinetic paramcters found for ipriflavone under the feed and fasted conditions were as follows:Cmax,37.24(4.22),and 13.65(1.08) ng/ml; Tmax,2.0(0.23),and 2.5(0.15)h; AUC0-τ,181.78(15.92),and 67.36(8.66) ng/m1·h-1(all,P<0.05).Conclusions:This improved LC-MS/MS method was sensitive and sententious for the determination of ipriflavone in human plasma.Significant difference of the pharmacokinetic of ipriflavone after drug adrninlstration under the feed and fast conditions was found in this study.