| abstract |
A controlled release system using a feedback-responsive controller reversibly changes the pH of the aqueous microenvironment of a biologically active compound sequestered in an aqueous-fluid-penetrable, aqueous-insoluble biocompatible material; the pH change is effected in response to a change in the concentration of the target compound in the aqueous medium surrounding the insoluble material; as a result of the pH change, the aqueous solubility and therefore the release rate of the active compound is reversibly changed. |