Preparation, pharmacokinetics and body distribution of silymarin-loaded solid lipid nanoparticles after oral administration

The purpose of this study was to investigate the body distribution of silymarin incorporated into solid lipid nanoparticles (SLNs) after oral administration. Silymarin-loaded solid lipid nanoparticles (SM-SLNs) were developed using Compritol 888 ATO, soybean lecithin and poloxamer 188. Two kinds of SM-SLNs were prepared using a hot and cold homogenization method. The particle size distribution, zeta potential, drug-loading (DL), and entrapment efficiency (EE) were investigated in detail. The in vitro release of both SM-SLNs preparations was studied by a bulk-equilibrium reverse dialysis bag technique at pH 7.4 using phosphate-buffered saline. The concentrations of silybin were determined by high-performance liquid chromatography. The in vitro release experiments showed that a prolonged drug release can be achieved from the SM-SLNs produced by cold homogenization (cold-SM-SLNs). Therefore, cold-SM-SLNs were used for all further body distribution studies. The relative bioavailability of the cold-SM-SLNs was 2.79-fold higher compared to the SM suspension. Except for the kidneys, the AUC of the cold-SM-SLNs was higher in all tested organs than that of the SM suspension including the liver. The results indicated that the cold-SM-SLNs can improve the oral bioavailability of SM and this might be used for the oral drug targeting system for SM to the liver.