Preparation and characterization of Furosemide-Eudragit controlled release systems.

Solid dispersions and physical mixtures were prepared and characterized by X-ray diffraction, infrared spectroscopy, electronic microscopy and dissolution rate studies. The characterization with X-ray diffraction showed a transition from the crystalline to the amorphous phase. A new phase near 50% Furosemide concentration with both types of carriers was present. From infrared spectroscopy strong interactions between amine and carbonyl groups from both the Furosemide and the polymers were found. Electronic microscopy analysis showed that the Furosemide changed its crystalline habit from needle to a new spherical phase, with diameter near to 1 microm. Solid dispersions were prepared in order to modify the system characteristics. The Furosemide dissolution rate was determined in order to follow the behavioural changes of the system. Scanning electron microscopy showed the presence of micro spheres within the polymeric matrix, and the channels formed due to the Furosemide dissolution inside the Eudragit: this fact modified the release pattern of the Furosemide system.