A MULTIPLE EMULSION METHOD TO ENTRAP A LIPOPHILIC COMPOUND INTO CHITOSAN MICROSPHERES

A new method for preparation of chitosan microspheres loaded with an h ydrophobic drug, ketoprofen, was developed. It is an emulsification/so lvent evaporation process carried out in mild conditions and particula rly useful for microencapsulation of thermally sensitive drugs. This m ethod can be additionally combined to physical and chemical cross-link ing in order to modulate drug release. Physical cross-linking was carr ied out by dry heating chitosan microspheres at fixed temperatures and for different times. Glutaraldehyde at different concentrations was u sed 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, su rface characteristics and size distribution; chitosan/ketoprofen inter actions inside microspheres were investigated by differential scanning calorimetry and powder X-ray difractometry. Ketoprofen contents insid e the microspheres and in vitro drug release profiles were also determ ined. (C) 1997 Elsevier Science B.V.