US5008050A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Extrusion technique for producing unilamellar vesicles
Assignee: Cephalon Ltd
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Filing: 1989-02-13
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Granted: 1991-04-16
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Expires: 2009-02-13
Abstract
Abstract A method for reducing the lamellarity of a population of liposomes is provided which comprises repeatedly passing the liposomes under pressure through a filter which has a pore size equal to or less than about 100 nm. In certain embodiments, the method is used to convert a population of previously formed multilamellar liposomes into a population of substantially unilamellar liposomes. In accordance with other aspects of the disclosure, liposomes are prepared directly from a lipid powder or pellet and buffer without the use of any solvents, detergents or other extraneous materials.
Inventors
- 👤 Pieter R. Cullis
- 👤 Michael J. Hope
- 👤 Marcel B. Bally
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:03
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/10; A61K9/127; A61K9/1277; B; B01; B01D; B01D61/00; B01D61/14; B01D61/147; B01D61/18; B01D2317/00; B01D2317/02; Y; Y10; Y10S; Y10S436/00; Y10S436/829; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2984
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
37 words
A method for reducing the lamellarity of a population of liposomes comprising repeatedly passing the liposomes under pressure through a filter which has a pore size (equal to or less than) no larger than about 100 nm.
Claim 2
Independent Claim
37 words
A method for reducing the lamellarity of a population of liposomes comprising repeatedly passing the liposomes under pressure through a filter which has a pore size (equal to or less than) no larger than about 100 nm.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein the population of liposomes is passed through the filter more than two times.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the population of liposomes is passed through the filter at a pressure greater than 100 pounds per square inch.
Claim 5
Dependent Claim
23 words
The method of claim 3 wherein the flow rate through the filter is greater than or equal to about 20 milliliters per minute.
Claim 6
Dependent Claim
12 words
The method of claim 1 wherein the filter has straight through channels.
Claim 7
Dependent Claim
12 words
The method of claim 5 wherein the filter is a polycarbonate filter.
Claim 8
Dependent Claim
17 words
The method of claim 6 wherein the filter comprises two or more polycarbonate filters arranged in series.
Claim 9
Dependent Claim
18 words
The method of claim 1 wherein the population of liposomes has a lipid concentration greater than 60 umol/ml.
Claim 10
Dependent Claim
37 words
The method of claim 1 wherein the population of liposomes is passed through the filter more than two times at a pressure greater than 100 pounds per square inch and wherein the filter has straight through channels.
Claim 11
Independent Claim
40 words
A method for preparing a population of substantially unilamellar liposomes comprising the steps of: (a) preparing multilamellar liposomes; and (b) repeatedly passing the liposomes under pressure through a filter which has a pore size no larger than about 100 nm.
Claim 12
Independent Claim
40 words
A method for preparing a population of substantially unilamellar liposomes comprising the steps of: (a) preparing multilamellar liposomes; and (b) repeatedly passing the liposomes under pressure through a filter which has a pore size no larger than about 100 nm.
Claim 13
Dependent Claim
17 words
The method of claim 10 wherein the liposomes are passed through the filter more than two times.
Claim 14
Dependent Claim
23 words
The method of claim 10 wherein the liposomes are passed through the filter at a pressure greater than 100 pounds per square inch.
Claim 15
Dependent Claim
23 words
The method of claim 10 wherein the flow rate through the filter is greater than or equal to about 20 milliliters per minute.
Claim 16
Dependent Claim
12 words
The method of claim 10 wherein the filter has straight through channels.
Claim 17
Dependent Claim
12 words
The method of claim 14 wherein the filter is a polycarbonate filter.
Claim 18
Dependent Claim
17 words
The method of claim 15 wherein the filter comprises two or more polycarbonate filters arranged in series.
Claim 19
Dependent Claim
18 words
The method of claim 10 wherein the population of liposomes has a lipid concentration greater than 60 umol/ml.
Claim 20
Dependent Claim
23 words
The method of claim 10 wherein the multilamellar liposomes are prepared by mechanical agitation of an aqueous suspension of one or more lipids.
Claim 21
Dependent Claim
22 words
The method of claim 10 including the additional step of subjecting the liposomes to a freeze-thaw cycle to increase their trapped volumes.
Claim 22
Dependent Claim
53 words
The method of claim 10 wherein the multilamellar liposomes are prepared by mechanical agitation of an aqueous suspension of one or more lipids, wherein the liposomes are passed through the filter more than two times at a pressure greater than 100 pounds per square inch, and wherein the filter has straight through channels.
Claim 23
Dependent Claim
22 words
The method of claim 20 including the additional step of subjecting the liposomes to a freeze-thaw cycle to increase their trapped volumes.
Claim 24
Independent Claim
77 words
A method for preparing liposomes without the use of solvents, detergents or other extraneous materials comprising the steps of: (a) preparing a mixture of a lipid powder or pellet and an aqueous buffer; and (b) repeatedly passing the mixture under pressure through a filter, wherein the filter has a pore size less than or equal to about 100 nm, the mixture is passed through the filter more than two times, and the resulting liposomes are substantially unilamellar.
Claim 25
Independent Claim
77 words
A method for preparing liposomes without the use of solvents, detergents or other extraneous materials comprising the steps of: (a) preparing a mixture of a lipid powder or pellet and an aqueous buffer; and (b) repeatedly passing the mixture under pressure through a filter, wherein the filter has a pore size less than or equal to about 100 nm, the mixture is passed through the filter more than two times, and the resulting liposomes are substantially unilamellar.
Claim 26
Dependent Claim
23 words
The method of claim 22 wherein the mixture is passed through the filter at a pressure greater than 100 pounds per square inch.
Claim 27
Dependent Claim
23 words
The method of claim 23 wherein the flow rate through the filter is greater than or equal to about 20 milliliters per minute.
Claim 28
Dependent Claim
12 words
The method of claim 23 wherein the filter has straight through channels.
Claim 29
Dependent Claim
12 words
The method of claim 25 wherein the filter is a polycarbonate filter.
Claim 30
Dependent Claim
17 words
The method of claim 26 wherein the filter comprises two or more polycarbonate filters arranged in series.
Claim 31
Dependent Claim
16 words
The method of claim 22 wherein the mixture has a lipid concentration greater than 60 umol/ml.
Claim 32
Dependent Claim
22 words
The method of claim 22 including the additional step of subjecting the liposomes to a freeze-thaw cycle to increase their trapped volumes.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-15 | 1994-10-15 | 1995-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-15 | 1998-10-15 | 1999-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-15 | 2002-10-15 | 2003-04-16 | $7700.00 | Window Closed / Lapsed |