[Preparation of silybin-phospholipid complex and its bioavailability in rats]

To prepare silybin-phospholipid complex and study its physicochemical properties. To compare the pharmacokinetic characteristics and bioavailability after oral administration of silybinphospholipid complex and silybin material in rats.

Using acetone as a reaction medium, silybin and phospholipid were resolved into the medium, when the organic solvent was clear, then removed under vacuum evaporation, silybin-phospholipid complex was obtained. The new complex' s physicochemical properties including DSC, UV, IR were determined. The concentrations of non-conjugated and total silybin after oral administration of silybin-phospholipid complex and silybin material at different time in rats were determined by RP-HPLC. The pharmacokinetic parameters were computed by software program 3P97.

Experiment results showed that silybin and phospholipid in the silybin-phospholipid complex were combined by non-covalent-bond, not forming a new compound and the solubility of silybin-phospholipid complex in water and n-octanol was effectively enhanced. It was found that mean plasma concentration-time curve of silybin after oral administration of silybin-phospholipid complex in rats was in accordance with one-compartment model with first-order absorption. Pharmacokinetic parameters of non-conjugated and total silybin in rats were respectively T(max) 10 min and 2 h; C(max) 0.11 and 1.08 microg x mL(-1); T1/2 2.18 and 3.84 h; AUC(0-infinity) 1.71 and 12.94 microg x mL(-1) x h. However, after oral administration of silybin material, plasma levels of both non-conjugated and total silybin were within the analytical detection limit.

It was concluded that after oral administration of silybin-phospholipid complex in rats the bioavailability of silybin increased greatly. This was mainly due to an obvious improvement of the lipophilic property of silybin-phospholipid complex compared with silybin material and an increase in gastrointestinal absorption.