Preparation of silymarin proliposome: a new way to increase oral bioavailability of silymarin in beagle dogs.

The aim of the present study was to find a method to increase oral bioavailability of silymarin, that is to say, by the preparation of silymarin proliposome and to compare the pharmacokinetic characteristics and bioavailability after oral administration of silymarin proliposome and silymarin in beagle dogs. Silymarin proliposome was prepared by the film-deposition on carriers. After the proliposome was contacted with water, the silymarin liposome suspensions formed automatically. The tests of physicochemical properties including SEM, TEM, encapsulation efficiency, dissolution studies, particle size of the reconstituted liposome and stability of the silymarin proliposome were determined by laser-particle-sizer, HPLC, etc. The concentrations of silymarin in plasma of beagle dogs and its pharmacokinetic behaviors after oral administration of silymarin liposome suspensions and silymarin were studied by RP-HPLC. The pharmacokinetic parameters were computed by software program 3p97. The encapsulation efficiency of silymarin liposome could be more than 90%, with an average particle size of about 196.4 nm and the proliposome appeared a very stability at 40 degrees C during 3 months. It was found that mean plasma concentration-time curves of silymarin after oral administration of liposome suspensions and silymarin in beagle dogs were both in accordance with open two-compartments model and first-order absorption. Pharmacokinetic parameters of silymarin proliposome and silymarin in beagle dogs were Tmax both 30 min; Cmax 472.62 and 89.78 ng mL(-1); and AUC0-infinity 2606.21 and 697 ng mL(-1)h, respectively. The high bioavailability of silymarin proliposome could be obtained by oral administration. Silymarin proliposome was stable and did enchance the gastrointestinal absorption of silymarin.