Formulation and Characterization of Solid Dispersed, Hepatoprotective Agent Silymarin

Silymarin, a hepatoprotective agent has poor aqueous solubility and high permeability [class II drug]. Its absorption is dissolution rate limited. In order to improve the dissolution profile of silymarin solubility enhancement techniques were employed. Among the various techniques, solid dispersions were employed due to its feasibility. Polymers used were HPMC and PEG. Silymarin was formulated by kneading method and solvent evaporation method, where HPMC and PEG were used in different ratios of drug: polymer. Polymer characterization for the prepared solid dispersion was done using FT-IR, XRPD, SEM and DSC. In vitro dissolution studies were carried out in 0.1M HCl and phosphate buffer mixed (pH 6.8). From the in vitro studies, dissolution efficiency and drug release kinetics was also calculated. FT-IR studies revealed that there was no interaction between the drug and the polymers used. DSC, XRPD and SEM supported the existence of silymarin in amorphous state, in the prepared solid dispersions. Drug content analysis showed maximum drug release of 101.03 for solid dispersion prepared using drug: HPMC in the ratio of 1:3 [KM2] using polysorbate 80, employing kneading method. In vitro release of KM2 was found to be 98.87 ± 0.32 in 0.1 M HCl buffer.  Kneading method proved to be superior to solvent evaporation method. Compared to the pure drug silymarin, solid dispersions [KM2] gave a 2.2 fold increase in the dissolution profile.