Formulation and evaluation of vinylpyrrolidone/vinylacetate copolymer microspheres with griseofulvin

Regular spherical microspheres of 220-260 microns average size have been prepared from vinylpyrrolidone/vinylacetate copolymer using a solvent evaporation method. Griseofulvin has been incorporated into these microspheres and its physical characterization has been carried out by differential scanning calorimetry (DSC), X-ray diffractometry and X-ray photoelectron spectroscopy. An increase of solubility was observed only with the 1:3 drug/polymer microspheres and the comparison of the dissolution profiles of microspheres with pure griseofulvin resulted in an enhancing effect. Furthermore the release rate of griseofulvin, incorporated into the microspheres, was shown to be biphasic and dependent upon the penetration of water into the microspheres, hydration and dissolution of the polymer and finally dissolution of the drug.