Controlled release systems composed of hydrophobic polymers such as ethylene-vinyl acetate copolymer have proven useful for releasing various polypeptides and other macromolecules for over 100 days. However, the release mechanism has never been elucidated. Evidence by microscopy is presented suggesting that release occurs through interconnecting pores formed by the macromolecules themselves. A mathematical model has been developed and used to predict the release rates of different proteins.
Bibliographical noteFunding Information:
This work was supported by NIH grant GM26698. We thank Dean Hsieh and Andrew Braunstein for assistance.