Effect of processing temperature on Eudragit RS PO microsphere characteristics in the solvent evaporation process

Eudragit RS PO microspheres containing stavudine as a model drug were prepared by the solvent evaporation method using acetone liquid paraffin system. The influence of processing temperature: 10, 30 and 40 degrees C on various parameters like particle shape, size distribution, drug loading, drug polymer interaction and release kinetic were studied. It was found that at lower temperature (10 degrees C) small particles of irregular size, rough and wrinkled surface were formed, whereas higher temperature gradually increases the particle size as well as improves the shape and smoothness of microspheres. It was found that temperature had no effect on encapsulation efficiency and drug polymer compatibility. Drug release rate from microspheres were found to be a function of mean particle size distribution.