Physicochemical Characterization and Dissolution Study of Solid Dispersions of Furosemide with Polyethylene Glycol 6000 and Polyvinylpyrrolidone K30

Solid dispersions traditionally have been used as effective methods to improve the dissolution properties and bioavailability of poorly water-soluble drugs. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, furosemide, by a solid dispersion technique. Solid dispersions were prepared using polyethylene glycol 6000 (PEG 6000) and polyvinylpyrrolidone K30 (PVP K30) in different drug-to-carrier ratios. Dispersions with PEG 6000 were prepared by fusion-cooling and solvent evaporation, while dispersions containing PVP K30 were prepared by solvent evaporation technique. These new formulations were characterized in the liquid state by phase solubility studies and in the solid state by differential scanning calorimetry, powder X-ray diffraction, and FTIR spectroscopy. The aqueous solubility of furosemide was favored by the presence of both polymers. Solid state characterizations indicated that furosemide was present as an amorphous material and entrapped in polymer matrix. In contrast to the very slow dissolution rate of pure furosemide, the dispersion of the drug in the polymers considerably enhanced the dissolution rate. Solid dispersion prepared with PEG showed the most improvement in wettability and dissolution rate of furosemide. Even physical mixtures of furosemide prepared with both polymers also showed better dissolution profiles as compared with that of pure furosemide. Tablets prepared using solid dispersions showed significant improvement in the release profile of furosemide as compared with conventional tablets prepared using furosemide without PEG or PVP.