The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 12, 1990
Filed:
Jul. 11, 1988
Margaret A Wheatley, Norristown, PA (US);
Robert S Langer, Somerville, MA (US);
Herman N Eisen, Waban, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
A controlled release system for delivery of a biologically-active substance. In one embodiment, there is a delayed release of a biologically-active substance. In a second embodiment, the delayed release is preceded by an initial release of biologically active substance. In other variations of the system, there are mulitple discrete releases over time or a continuous slow release combined with discrete releases. The delayed exposure is achieved through the design and construction of the system, specifically, formation of ionically-coated microcapsules around the biologically-active substance in conjunction with a microcapsule core-degrading enzyme. Release of active substance takes place in a burst at such a time as the core degrading enzyme has reduced the core to a molecular weight too low to support enough interaction with the cationic skin to maintain its integrity as a skin. In one example, microcapsules are formed of an ionically cross-linked polysaccharide, calcium alginate, which is further ionically coated with a poly-cationic skin of poly-L-lysine. The capsule coating serves a dual purpose: to control diffusion of the biologically-active substance and the core-degrading enzyme and as a substrate for the mechanism by which the biologically-active substance is released after a time delay.