Chitosan microspheres of nifedipine and nifedipine-cyclodextrin inclusion complexes

Chitosan microspheres of nifedipine and nifedipine-cyclodextrin complexes were prepared by the glutaraldehyde cross-linking of chitosan. Microspheres having different degrees of swelling were made by varying the cross-linking density. Drug incorporation efficiencies exceeding 70% could be achieved for this drug. In vitro release rates were influenced by the cross-linking density, particle size and initial drug loading in the microspheres. While the solubility of nifedipine was enhanced by inclusion into a cyclodextrin complex, the drug release from the complex was significantly reduced. In addition the drug release mechanisms were discussed.