Solid nanostructured lipid carriers loaded with silymarin for oral delivery: Formulation development and evaluation

The present study was aimed at preparing stable dry adsorbed nanoparticles (DANs) of silymarin loaded nanostructured lipid carriers (NLCs). The prepared silymarin loaded NLCs and DANs were characterized for various quality parameters. Silymarin loaded NLCs were prepared by a modified hot melt emulsification ultra-sonication method using glyceryl monostearate (GMS), capmul MCM C8 EP (CAP) and gelucire 50/13 (G50/13) as solid lipid, liquid lipid and surfactant respectively. For better stability, NLC dispersion was converted into DANs by adsorbing them onto some suitable carriers. NLCs and DANs were characterized for particle size, polydispersity index, zeta potential, entrapment efficiency, drug loading, assay, thermal behavior, crystallinity and morphological study. The optimized NLCs have a mean particle size of 206.1±012.5 nm (size distribution of 0.249±0.058), a zeta potential of -32.5±1.2 mV with high entrapment of 95.60±0.45% and drug loading of 1.90±0.08%. The X-ray diffraction and endothermic peaks confirmed the maximum encapsulation of active in lipid matrices. The particles were spherical with smooth surface morphology. In-vitro release studies showed sustained drug release for up to 24 h. Ex-vivo permeation in the presence and absence of lymphatic blocker indicates the uptake of silymarin loaded NLCs by the lymphatic route. Silymarin loaded NLCs prepared had a nanosize distribution with high entrapment efficiency. The ex-vivo permeation study for optimized NLC formulation exhibited the lymphatic uptake of active. Dispersion stability was increased by preparing the DANs. The solid dry powder is used for oral reconstitution and can be further converted into tablets or filled into capsules.