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US4921757A Expired / Lapsed US ⏱️ 0.0 years remaining

System for delayed and pulsed release of biologically active substances

Assignee: Massachusetts Institute of Technology
•
Filing: 1987-09-03
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Granted: 1990-05-01
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Expires: 2007-09-03
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Abstract

Abstract A system for controlled release both in vivo and in vitro of entrapped substances, either at a constant rate over a period of time or in discrete pulses, is disclosed. Biologically active substances, such as drugs, hormones, enzymes, genetic material, antigens including viruses, vaccines, or inorganic material such as dyes and nutrients, are entrapped in liposomes which are protected from the biological environment by encapsulation within semi-permeable microcapsules or a permeable polymeric matrix. Release of the entrapped substance into the surrounding environment is governed by the permeability of both the liposome and surrounding matrix to the substance. Permeability of the liposome is engineered by modifying the composition and method for making the liposomes, thereby producing liposomes which are sensitive to a specific stimuli such as temperature, pH, or light; or by including a phospholipase within some or all of the liposomes or the surrounding matrix; or by destabilizing the liposome to break down over a period of time; or by any combination of these features.

Inventors

  • 👤 Margaret A. Wheatley
  • 👤 Robert S. Langer
  • 👤 Herman N. Eisen

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 17:12
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/70; A61K9/7023; A61K9/703; A61K9/10; A61K9/127; A61K9/48; A61K9/50; A61K9/5005; A61K9/5021; A61K9/5026; A61K9/5031; A61K9/7084; Y; Y10; Y10S; Y10S436/00; Y10S436/829; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2984

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 43 words
A composition of for controlled release of entrapped substances comprising: a permeable polymeric matrix, liposomes located within said matrix, and a first substance entrapped within said liposomes, and a phospholipase located in said matrix exterior to said liposomes and bound to said matrix.
Claim 2
Dependent Claim 43 words
A composition of for controlled release of entrapped substances comprising: a permeable polymeric matrix, liposomes located within said matrix, and a first substance entrapped within said liposomes, and a phospholipase located in said matrix exterior to said liposomes and bound to said matrix.
Claim 3
Dependent Claim 11 words
The composition of claim 1 wherein said phospholipase molecules are crosslinked.
Claim 4
Dependent Claim 45 words
A composition for controlled release of entrapped substances comprising: a permeable polymeric matrix, liposomes located within said matrix, and a phospholipase located in said matrix exterior to said liposomes and bound to a soluble polymer substrate wherein said matrix is impermeable to said polymer substrate.
Claim 5
Dependent Claim 45 words
A composition for controlled release of entrapped substances comprising: a permeable polymeric matrix, liposomes located within said matrix, and a phospholipase located in said matrix exterior to said liposomes and bound to a soluble polymer substrate wherein said matrix is impermeable to said polymer substrate.
Claim 6
Independent Claim 64 words
A method for controlled release of an entrapped substance comprising: selecting a substance to be entrapped, entrapping the selected substance within liposomes, encapsulating the substance-containing liposomes within a permeable polymeric matrix, binding a phospholipase which destabilizes the liposomes within the matrix to prevent diffusion of the enzyme from the matrix, and locating the matrix-encapsulated liposomes at a site for release of the entrapped substance.
Claim 7
Independent Claim 64 words
A method for controlled release of an entrapped substance comprising: selecting a substance to be entrapped, entrapping the selected substance within liposomes, encapsulating the substance-containing liposomes within a permeable polymeric matrix, binding a phospholipase which destabilizes the liposomes within the matrix to prevent diffusion of the enzyme from the matrix, and locating the matrix-encapsulated liposomes at a site for release of the entrapped substance.

References Cited (Backward Citations)

US4217344A Cited
US4145410A Cited
US4352883A Cited
US4314557A Cited
US4731210A Cited
WO1985003640A1 Cited
US4708861A Cited
US4761288A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1993-04-30 1993-10-30 1994-05-01 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1997-04-30 1997-10-30 1998-05-01 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2001-04-30 2001-10-30 2002-05-01 $7700.00 Window Closed / Lapsed

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