Liposome extrusion method

• US 4,737,323 A
• Filed: 02/13/1986
• Issued: 04/12/1988
• Est. Priority Date: 02/13/1986
• Status: Expired due to Term

• Current Assignee: Liposome Technology, Inc.
• Original Assignee: Liposome Technology, Inc.
• Inventors: Martin, Francis J., Morano, Jacqueline K.
• Primary Examiner(s): Lovering, Richard D.
• Application Number:
  US06/829,710
• Time in Patent Office: 789 Days
• Field of Search: 264/4.3, 428/402.2, 424/19, 424/38, 424/420, 424/450, 436/829, 210/500.23, 210/500.26
• US Class Current: 264/4.3
• CPC Class Codes: A61K 9/1277 Processes for preparing; Proliposomes
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 35/00 Shaped ceramic products characterised by their composition porous ceramic products C04B38/00; ceramic articles characterised by particular shape, see the relevant classes, e.g. linings for casting ladles, tundishes, cups or the like B22D41/02; ceramic substrates for microelectronic semi-conductors H01L23/15; Ceramics compositions containing free metal bonded to carbides, diamond, oxides, borides, nitrides, silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides or sulfides other than as macroscopic reinforcing agents C22C; shaping of ceramics B28B; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products chemical preparation of powders of inorganic compounds C01; infiltration of sintered ceramic preforms with molten metal C04B41/51
• CPC Class Codes: C04B 38/0051 characterised by the pore size, pore shape or kind of porosity
• CPC Class Codes: Y10S 436/829 Liposomes, e.g. encapsulation
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]

Abstract

A suspension of liposomes whose sizes are predominantly greater than about 1 micron is passed through an asymmetric ceramic filter whose inner-surface pore size is about 1 micron. The processed liposomes have a selected average size of about 0.4 microns or less, depending on the number of filter cycles, and a narrow distribution.

Claims

1. A method of producing a suspension of liposomes which have uniform sizes and a selected average size of less than about 0.4 microns, said method comprising:

providing a suspension of heterogeneous-size liposomes containing a substantial portion with sizes greater than 1.0 micron in size, and

passing the suspension under pressure through an asymmetric ceramic filter whose inner-surface pore size is greater than the desired average liposome size and no greater than about 1 micron.

2. The method of claim 1, wherein the liposome suspension is passed through the filter in an inside-to-outside direction.

3. The method of claim 1 wherein the membrane is a Ceraflow™

asymmetric ceramic filter.

4. The method of claim 1, for producing a suspension of liposomes having a selected average size of between about 0.3 and 0.4 microns, wherein said asymmetric filter has an inner-surface pore size of about 1 micron.

5. The method of claim 1, for producing a suspension of liposomes having a selected average size of between about 0.2 and 0.3 microns, wherein said asymmetric filter has an inner-surface pore size of about 0.45 microns in size.

6. The method of claim 5, for producing a suspension of liposome having a selected average size between about 0.2 and 0.3 microns, which further includes passing the suspension repeatedly through the filter, in an inside-to-outside direction, until the desired liposome average size is achieved.

7. The method of claim 6 which further includes alternately passing the suspension through the filter in an outside-to-inside direction.