Objective
To evaluate the effect of Polyethylene glycol and β-cyclodextrin on the solubility and dissolution of silymarine, a poorly water soluble herbal drug.
Methodology
Effects of beta cyclodextrins and Polyethylene glycol on solubility of sylimarine were evaluated by phase solubility studies both separately as well as in combination. Solid inclusion complexes of silymarine β-cyclodextrin in 1:1 molar ratio were prepared with and without polyethylene glycol by kneading method then evaluated for solubility dissolution and physical nature by XRD, FT-IR and NMR spectroscopy studies.
Results
The aqueous solubility of silymarine was linearly increased as a function of the concentration of β-cyclodextrin alone and in the presence of polyethylene glycol. Beta cyclodextrin formed molecular inclusion complexes with sylimarine in1:1 molar ratio as revealed by phase solubility diagram. The ternary complexes of silymarine, β-cyclodextrin and polyethylene glycol demonstrated better dissolution than those of silymarine and its binary complexes with β-cyclodextrin alone. Silymarine - β-cyclodextrin complex caused 1.3 fold increase in the dissolution rate of silymarine, which was further increased up to 1.7 fold in presence of small amount of polyethylene glycol.
Conclusion
The presence of polyethylene glycol markedly enhances the molecular complexation and solubilizing efficiencies of β-cyclodextrin on sylimarine.
Key words: Keywords: Silymarine, Cyclodextrin, ternary complex, PEG 6000, Solubility, Dissolution rate.
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