US4927637A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liposome extrusion method
Assignee: Liposome Technology Inc
•
Filing: 1989-01-17
•
Granted: 1990-05-22
•
Expires: 2009-01-17
Abstract
Abstract A suspension of heterogeneous size liposomes is passed through a polymer filter having a web-like construction providing a network of interconnected, tortuous-path capillary pores, and a membrane thickness of at least about 100 microns. The processed liposomes have a selected average size less than about 0.4 microns, and a narrow size distribution.
Inventors
- 👤 Jacqueline K. Morano
- 👤 Francis J. Martin
- 👤 Martin Woodle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:14
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/10; A61K9/127; A61K9/1277
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
99 words
A method of producing a suspension of liposomes which have uniform sizes and a selected average size in the size range between about 0.1 and 0.4 microns, said method comprising providing a suspension of heterogeneous-size liposomes containing a substantial portion with sizes greater than 1.0 micron, and passing the suspension through a polymer membrane filter characterized by: (a) a web-like construction providing a network of interconnected, tortuous-path capillary pores; (b) a membrane thickness of at least about 100 microns; and (c) a membrane pore size rating which is approximately the same as the selected average size of the liposomes.
Claim 2
Independent Claim
99 words
A method of producing a suspension of liposomes which have uniform sizes and a selected average size in the size range between about 0.1 and 0.4 microns, said method comprising providing a suspension of heterogeneous-size liposomes containing a substantial portion with sizes greater than 1.0 micron, and passing the suspension through a polymer membrane filter characterized by: (a) a web-like construction providing a network of interconnected, tortuous-path capillary pores; (b) a membrane thickness of at least about 100 microns; and (c) a membrane pore size rating which is approximately the same as the selected average size of the liposomes.
Claim 3
Dependent Claim
22 words
The method of claim 1, wherein the polymer forming the filter is selected from the group consisting of polysulfone, nylon, and polypropylene.
Claim 4
Dependent Claim
33 words
The method of claim 1, for producing a suspension of liposome having a selected average size between about 0.2 and 0.3 microns, wherein the rated pore size of the filter is 0.2 microns.
Claim 5
Dependent Claim
33 words
The method of claim 1, for producing a suspension of liposome having a selected average size between about 0.1 and 0.15 microns, wherein the rated pore size of the filter is 0.1 microns.
Claim 6
Dependent Claim
35 words
The method of claim 1, for producing a suspension of liposome having a polydispersity no greater than about 0.125, wherein the filter is a polysulfone filter having a rated pore size of 0.1 or 0.2.
Claim 7
Independent Claim
114 words
A method of producing liposomes having a selected average size of no greater than about 0.4 microns and a polydispersity of no greater than about 0.125, comprising providing a dispersion of liposomes containing a substantial portion with sizes greater than 0.4 microns and a polydispersity greater than about 0.18, passing the suspension through a polysulfone membrane filter characterized by (a) a web-like construction providing a network of interconnected, tortuous-path capillary pores; (b) a membrane thickness of at least about 100 microns; and (c) a membrane pore size rating which is approximately the same as the desired average size of the liposomes, and repeating said passing step 2-4 times until the desired polydispersity is achieved.
Claim 8
Independent Claim
114 words
A method of producing liposomes having a selected average size of no greater than about 0.4 microns and a polydispersity of no greater than about 0.125, comprising providing a dispersion of liposomes containing a substantial portion with sizes greater than 0.4 microns and a polydispersity greater than about 0.18, passing the suspension through a polysulfone membrane filter characterized by (a) a web-like construction providing a network of interconnected, tortuous-path capillary pores; (b) a membrane thickness of at least about 100 microns; and (c) a membrane pore size rating which is approximately the same as the desired average size of the liposomes, and repeating said passing step 2-4 times until the desired polydispersity is achieved.
Claim 9
Dependent Claim
28 words
The method of claim 6, wherein the dispersion provided has a substantial portion of liposome sizes greater than about 1 micron, and a polydispersity greater than about 0.25.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-21 | 1993-11-20 | 1994-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-21 | 1997-11-20 | 1998-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-21 | 2001-11-20 | 2002-05-22 | $7700.00 | Window Closed / Lapsed |