Polyanhydride microspheres as drug carriers I. Hot-melt microencapsulation

Polyanhydride microspheres containing dyes (acid-orange),p-nitroaniline) or drugs (insulin) were prepared and evaluated for the purpose of creating a bioerodible system with the capability of producing controlled release for molecules of any size, including macromolecules. A “hot melt” microencapsulation method was employed. The model polymer used was poly[bis(p-itcarboxy phenoxy)propane anhydride], copolymerized with sebacic acid (PCPP-SA). The microspheres degrade heterogeneously when low levels of a hydrophilic drug are used; a well-defined degrading zone appears during the degradation process. Insulin-incorporated microspheres implanted into diabetic rats resulted in normoglycemia for a period of 3 to 4 days.