Degradation

The abrasion and abasement of a polymer call how the polymer physically loses accumulation (degrades). The two accepted abrasion mechanisms are apparent and aggregate erosion. Polyanhydrides are apparent acerbic polymers. Apparent acerbic polymers do not acquiesce baptize to access into the material. They abrade band by layer, like a lollipop. The berserk courage with hydrolytically labile anhydride linkages allows hydrolytic abasement to be controlled by manipulating the polymer composition. This abetment can action by abacus a hydrophilic accumulation to the polyanhydride to accomplish a copolymer. Polyanhydride copolymers with hydrophilic groups display aggregate acerbic characteristics. Aggregate acerbic polymers booty in baptize like a blot (throughout the material) and abrade central and on the apparent of the polymer.

Drug absolution from aggregate acerbic polymers is difficult to characterize because the primary approach of absolution from these polymers is diffusion. Unlike apparent acerbic polymers, aggregate acerbic polymers appearance a actual anemic accord amid the amount of polymer abasement and the amount of biologic release. Therefore, the development of apparent acerbic polyanhydrides congenital into the aggregate acerbic polymers is of added importance.