Abstract: Aim To prepare and characterize solid dispersions of silymarin with the intention of improving their dissolution properties. Methods The solid dispersions were prepared by the fusion method with polyethylene glycol 6000 (PEG 6000) as the carrier. Evaluation of the properties of the dispersions was performed using dissolution studies, X-ray powder diffraction and Fourier-transform infrared (FT-IR) spectroscopy. Results The rate of dissolution of silymarin was considerably improved as compared with pure silymarin when formulated in solid dispersions with PEG 6000. The data of the X-ray diffraction showed some changes in the parameters of lattice spacing [d], peak position and relative intensities. FT-IR together with those from X-ray diffraction showed the absence of well-defined drug-polymer interactions. Conclusion The dissolution improvement of poorly soluble silymarin could be illuminated by the changes of the lattice parameters of PEG 6000 and the drug.

Key words: silymarin, silymarin, solid dispersions, solid dispersions, X-ray powder diffraction, X-ray powder diffraction, FT-IR spectroscopy, FT-IR spectroscopy, dissolution, dissolution, PEG 6000, PEG 6000