EVALUATION OF SPRAY-DRYING AS A METHOD TO PREPARE MICROPARTICLES FOR CONTROLLED DRUG-RELEASE

The possibility to obtain microcapsules or microspheres for controlled release by spray-drying is evaluated. Drugs of different solubilities like theophylline and sodium sulfamethazine, with Eudragit RS as coat ing polymer, are chosen.The polymer is used, either dissolved in an hy droalcoholic solution or suspended (pseudolatex) in water, in differen t weight ratios with the drug. The obtained solution or suspension is spray-dried. Scanning electron microscope analysis of the powders reve als no sign of microencapsulation. Moreover, only a fraction of the pa rticles has a spherical shape. For each spray-dried powder, a part of the obtained particles is compressed into tablets, and the rest is sto red. Dissolution studies in distilled water at 37 C are performed on p owders and tablets.