Formulation, characterization, and in vitro evaluation of silymarin-loaded lipid microspheres

The objective of our study was to incorporate and evaluate Silymarin, a chemically defined natural hepatoprotective agent, in lipid microstructured systems. Various constituents of lipid microspheres--namely, internal oily core; surfactant such as soyabean lecithin; and cosurfactants such as span 20, tween 20, tween 80, and propylene glycol--were tried in different concentrations to optimize the final formulation characteristics such as globule size range, structural integrity, sustainability, and percent drug-holding capacity. The final formulation (formulation A) was characterized with respect to size and morphology using transmission electron microscopy and laser diffraction technique. The enhanced mean percent release of 56.70+/- 2.03% was observed in 36 hr from silymarin-loaded lipid microspheres (formulation A), as compared to 18.67 +/- 0.192% with silymarin solution (formulation B). Thus, a stable delivery system having synergistic hepatoprotective effect of silymarin and soyabean lecithin could successively be produced for passive targeting to the liver.