RADIOLABELING OF POLYMER MICROSPHERES FOR SCINTIGRAPHIC INVESTIGATIONS BY NEUTRON-ACTIVATION .3. CHANGES IN THE PHYSICAL-PROPERTIES OF EUDRAGIT RS-SULFAPYRIDINE MICROSPHERES FROM INCORPORATING SAMARIUM OXIDE

Eudragit RS microspheres containing sulphapyridine and samarium oxide (Sm2O3) have been prepared using a solvent evaporation process. Micros pheres containing 1.1% w/w Sm2O3 were smaller, had a higher density, a nd released encapsulated drug significantly more slowly than samples c ontaining no Sm2O3. Electron microscopy revealed that in the presence of Sm2O3, the size and number of pores in the microsphere surface was markedly reduced, suggesting that it may be exerting an effect at the organic:aqueous interface during microsphere formation.