Eudragit(®) microparticles for the release of budesonide: a comparative study.

This study compares the behaviour of budesonide-containing microparticles made of Eudragit(®)RS or Eudragit(®)RS/Eudragit(®)RL 70:30 (w/w) prepared either by solvent evaporation or spray-drying technique. The loading efficiency of budesonide within microparticles was about 72% for microparticles prepared by solvent evaporation and around 78% for spray-dried microparticles. Thermal analyses were assessed to collect information about the structural stability of budesonide within the polymeric microspheres. The in vitro release was performed using simulating gastric (fasted state simulated gastric fluid) and intestinal (fasted state simulated intestinal fluid) fluids as the receiving solutions. After 3 h the drug release from Eudragit(®)RS/Eudragit(®)RL microparticles was about 6-fold higher than that obtained in the case of monopolymer microparticles. Using fasted state simulated intestinal fluid the drug was released between 4 and 30% in both types of preparations. Eudragit(®)RS microparticles showed a better protection of the drug from gastric acidity than those of Eudragit(®)RS/Eudragit(®)RL allowing us to propose Eudragit(®)RS microparticles as a hypothetical system of colon specific controlled delivery.