title: Analysis of biliary excretion of icariin in rats.
abstract: 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=AUCbile/AUCblood). 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.
authors.affiliation: Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei 112, Taiwan.
authors.forename: Yu-Tse
authors.initials: YT
authors.lastname: Wu
authors.forename: Chia-Wen
authors.initials: CW
authors.lastname: Lin
authors.forename: Lie-Chwen
authors.initials: LC
authors.lastname: Lin
authors.forename: Allen W
authors.initials: AW
authors.lastname: Chiu
authors.forename: Kuang-Kuo
authors.initials: KK
authors.lastname: Chen
authors.forename: Tung-Hu
authors.initials: TH
authors.lastname: Tsai
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D005419:Flavonoids / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D008297:Male; D058986:Phosphodiesterase 5 Inhibitors / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D005419:Flavonoids; D058986:Phosphodiesterase 5 Inhibitors; C056599:icariin