Abstract: Pharmacokinetics and bioavailability of Catechin Liposome were studied in 10 healthy rabbits following single intravenous (25mg/kg) and oral administration (25mg/kg)of the drug. Plasma concentrations of. Catechin Liposome were determined by high-performance liquid chromatography. The concentration-time data were fitted to a two-compartment model following a single intravenous injection in rabbits. The main pharmacokinetic parameters were as follows: distribution half-life (t_1/2α) (0.18±0.01)h,elimination half-life (t_1/2β) (1.52±0.08)h,apparent distribution volume (Vd) (4.48±0.24)L total body clearance (Cl_B) (2.05±0.07)L/h,the area under curve (AUC) (29.20±1.00)mg/(L.h). The drug concentration-time data also were fitted to a one-compartment open model with first order absorption after a single oral administration Catechin Liposome. The pharmacokinetic parameters were as follows: t_1/2k_α (0.27±0.03)h, t_1/2k_e(1.72±0.04)h, t_max (0.87±0.05) h, C_max 6.53±0.62βmg/L, AUC 25.90±1.34βmg/(L.h), bioavailability F 88.60±5.73%. Pharmacokinetic characteristics of Catechin Liposome in healthy rabbits showed a rapid absorption, the time to reach Cmax is short, slow elimination, long half-life, large apparent distribution volume, and high bioavailability of oral administration. The results showed：after Catechin was prepared in liposome form, the tissue distribution and pharmacokinetics were changed significantly.

Key words: Catechin, Liposome, Pharmacokinetics, Bioavailability, Rabbits