POLYANHYDRIDE MICROSPHERES .4. MORPHOLOGY AND CHARACTERIZATION OF SYSTEMS MADE BY SPRAY DRYING

The morphology of bioerodible polyanhydride microspheres produced by spray drying is described. Microspheres prepared from a variety of homo- and copolymers were studied and characterized using X-ray powder diffraction, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Crystalline polymers, such as poly(sebacic anhydride) (P(SA)) and poly(fumaric acid) (P(FA)), yielded microspheres with a crenalated and porous surface, as judged by SEM. Polymers, with lower crystallinity, such as copolymers of carboxyphenoxypropane and sebacic acid P(CPP-SA), yielded microspheres with a smooth external surface. Polymer crystallinity decreased after spray drying, for both blank and drug loaded microspheres.