A multiple emulsion method to entrap a lipophilic compound into chitosan microspheres

A new method for preparation of chitosan microspheres loaded with an hydrophobic drug, ketoprofen, was developed. It is an emulsification/solvent evaporation process carried out in mild conditions and particularly useful for microencapsulation of thermally sensitive drugs. This method can be additionally combined to physical and chemical cross-linking in order to modulate drug release. Physical cross-linking was carried out by dry heating chitosan microspheres at fixed temperatures and for different times. Glutaraldehyde at different concentrations was used as the chemical cross-linking agent on microspheres constituted by different theoretical ketoprofen/chitosan ratio (1:2, 1:4, 1:6 w/w). Chitosan microspheres were morphologically characterized for shape, surface characteristics and size distribution; chitosan/ketoprofen interactions inside microspheres were investigated by differential scanning calorimetry and powder X-ray difractometry. Ketoprofen contents inside the microspheres and in vitro drug release profiles were also determined. (C) 1997 Elsevier Science B.V.