INTERACTION BETWEEN NICARDIPINE HYDROCHLORIDE AND POLYMERIC MICROSPHERES FOR A CONTROLLED-RELEASE SYSTEM

The microspheres containing nicardipine hydrochloride (NCH) were prepa red by the solvent evaporation method using acrylic polymers, Eudragit RS and L. The results of the release experiments with microspheres pr oposed that there should exist an interaction between NCH and the acry lic polymers. The mechanism of this interaction was investigated by di fferential scanning calorimetry (DSC) and powder X-ray diffractometry (XRD). These analysis indicated that NCH and polymers interact at the molecular level, possibly NCH forming a solid solution with polymers. Furthermore, the formulations ended with a solid solution between NCH and acrylic polymers and their blends made possible the preparation of controlled release microspheres to retard and to enhance drug release rate at pH 1.2 and 7.5, respectively.