Pharmacokinetic study on baicalin and wogonoside in diabetic rats in vivo after oral administrating Huanglian-Jiedu Decoction

Objective To investigate the pharmacokinetic profiles of baicalin and wogonoside in diabe-tic rats in vivo,which are two major constituents in Huanglian-Jiedu Decoction(HJD).Methods The diabetic rats were induced by ip administration of streptozotocin(STZ).After the establishment of the method and the set-up of diabetic rats,the pharmacokinetic profiles of baicalin and wogonoside were investigated.Diabetic and normal rats were ig HJD extract,and then the blood samples were collected at the given time points.Contents of baicalin and wogonoside in diabetic and normal rat plasma were assayed by HPLC-UV method.The pharmacokinetic parameters(except Cmax and tmax) were analyzed by noncompartmental method.The area under the serum concentration-time curve(AUC0-t) was calculated using trapezoidal rule to the last point.Moreover,the presystemic metabolism of baicalin was investigated and compared to explore the pharmacokinetic difference by fermentation of baicalin in feces suspensions of normal and diabetic rats,respectively.Results The pharmacokinetic parameters of baicalin in normal and diabe-tic rats were:(4.50±1.92) and(7.5±1.0) h for tmax 2;(2.83±0.25) and(9.54±2.87) μg/mL for Cmax1,(2.56±0.63) and(6.58±1.15) μg/mL for Cmax2;(37.58±7.57) and(92.75±24.62) μg·h/mL for AUC(0～24),(6.6±2.4) and(12.64±3.35) h for t1/2,respectively.And the pharmacokinetic parameters of wogonoside in normal and diabetic rats were:(5.5±1.0) and(8.00±1.63) h for tmax 2;(1.36±0.17) and(6.16±1.40) μg/mL for Cmax1;(1.58±0.17) and(4.11±0.76) μg/mL for Cmax2;(27.02±3.72) and(58.16±16.43) μg·h/mL for AUC(0～24);(9.72±2.24) and(7.89±1.63) h for t1/2,respectively.The results indicated that Cmax1,Cmax2,AUC(0～24) of baicalin and wogonoside were significantly enhanced and t1/2 of baicalin was remarkably extended when compared with the normal rats.And the results also revealed that baicalin contained in HJD hydrolyzed more rapidly when incubated in the feces suspension of diabetic rats than in that of normal rats.Conclusion The results indicate that the pharmacokinetic difference of baicalin between diabetic and normal rats may result from the presystemic metabolism of baicalin.