Effects of the Eudragit and Drug Coat on the Release Behaviour of Poorly Soluble Drug by Solid Dispersion Technique

Solid dispersions traditionally have been used as effective methods to improve the dissolution properties and bioavailability of poorly water-soluble drugs. Furosemide a loop diuretic belonging to Biopharmaceutical Classification System (BCS) Class IV, has very poor water solubility. The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, furosemide, by solid dispersion technique as well as to evaluate the potential of Eudragit RL-100, RS-100 and Drug coat L -100, S -100 (methacrylic acid polymers) as carriers for solid dispersions. Solid dispersions were prepared by solvent evaporation technique. The solid dispersions were characterized for particle size, particle size distribution, solubility studies and interaction studies such as FTIR spectroscopy. Solid state characterizations i.e., X-Ray diffraction study; Differential Scanning Calorimetry and Scanning Electron Microscopy were also carried out for the best formulation. In contrast to the very slow dissolution rate of pure furosemide, the dispersion of the drug in the polymer considerably enhanced solubility. The aqueous solubility of furosemide was favoured by formulating it into a solid dispersion. Also it was concluded that Eudragit RL100 proved to be the best carrier.