[Preparation and evaluation of silybin nanocrystallines self-stabilizing Pickering emulsion]

A new silybin nanocrystallines self-stabilizing Pickering emulsion(SN-SSPE) was developed using the high pressure homogenization method to improve the oral bioavailability of silybin. The influences of homogenization pressure from 50 to 120 MPa and drug content from 100 mg to 1000 mg on the formation of SN-SSPE were studied. The morphology, structure and size of emulsion droplet in SN-SSPE were characterized using scanning electron micrograph and confocal laser scanning microscope.SN-SSPE was evaluated, including stability, in vitro release and in vivo oral bioavailability. The particle size of silybin nanocrystallines (SN-NC) was decreased as the pressure increased until 100 MPa. When the drug content reached 300 mg or above, stable SN-SSPE was formed from sufficient SN-NC covering surfaces of oil droplets completely. The emulsion droplet of SN-SSPE with the size of 27.3 ± 3.1 μm showed a core-shell structure consisting of oil droplet as core and SN-NC as shell.SN-SSPE showed a high stability over 40 days. In vitro release rate of SN-SSPE was faster than silybin coarse powder and similar to silybin nanocrystallines suspension(SN-NCS).After intragastric administration in rats, the peak concentration of SN-SSPE was increased by 2.5-fold and 2.3-fold compared with SN-NCS and silybin coarse powder, respectively. The AUC of SN-SSPE was increased by 1.4-fold and 3.8-fold compared with SN-NCS and silybin coarse powder, respectively. All these results showed that nanocrystallines of the poorly soluble drug could stabilize Pickering emulsions, which provides a promising application to the improvement of the oral bioavailability of poorly soluble drugs.