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Analysis of Biliary Excretion of Icariin in Rats

Wu, Yu-Tse, Lin, Chia-Wen, Lin, Lie-Chwen, Chiu, Allen W., Chen, Kuang-Kuo, Tsai, Tung-Hu
Journal of agricultural and food chemistry 2010 v.58 no.18 pp. 9905–9911
biliary tract, excretion, rats, animal models, bioactive properties, Epimedium, high performance liquid chromatography, Oriental traditional medicine, herbal medicines, bioavailability
Icariin is a bioactive herbal ingredient isolated from Epimedii Herba. This study evaluates the distribution of icariin in rats by microdialysis sampling and high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Microdialysis probes were simultaneously placed in the jugular vein, brain striatum, and bile duct of each anesthetized rat for sampling after the administration of icariin (dose = 10 or 20 mg/kg) via the femoral vein. The role of P-glycoprotein (P-gp) on icariin distribution was assessed by pretreatment with cyclosporine (CsA, dose = 20 mg/kg). This study is the first report of the biliary excretion of icarin in rats, defined as the blood-to-bile distribution (k value), calculated by dividing the area under the concentration−time curve (AUC) of icariin in bile by that in blood (k = AUC(bile)/AUC(blood)). The k values were 19.0 ± 5.9 and 18.8 ± 3.8 at the doses of 10 and 20 mg/kg, respectively. The decreased biliary excretion of icariin due to pretreatment with CsA was evidenced by the reduced k values (18.8 ± 3.8 vs 9.9 ± 1.9, p = 0.005). This work demonstrates that biliary excretion is the major elimination pathway for icariin disposition and that transporters, such as P-gp, might be related to icariin’s biliary excretion.