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Details for Patent: 5,766,627

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Details for Patent: 5,766,627

Title: Multivescular liposomes with controlled release of encapsulated biologically active substances
Abstract:A multivesicular liposome composition containing at least one acid other than a hydrohalic acid and at least one biologically active substance, the vesicles having defined size distribution, adjustable average size, internal chamber size and number, provides a controlled release rate of the biologically active substance from the composition. A process for making the composition features addition of a non-hydrohalic acid effective to sustain and control the rate of release of an encapsulated biologically active substance from the vesicles at therapeutic levels in vivo.
Inventor(s): Sankaram; Mantripragada Bhima (San Diego, CA), Kim; Sinil (Solana Beach, CA)
Assignee: Depotech (San Diego, CA)
Filing Date:May 23, 1997
Application Number:08/862,589
Claims:1. A process for producing a multivesicular liposome having multiple non-concentric chambers with internal membranes distributed as a network throughout, said process comprising the steps of:

(a) forming a water-in-oil emulsion from two immiscible components, the two immiscible components being 1) a lipid component comprising at least one organic solvent, at least one amphipathic lipid, and at least one neutral lipid lacking a hydrophilic head group, and 2) a first aqueous component; said water-in-oil emulsion further comprising a non-hydrohalic acid selected from the group consisting of perchloric, nitric, formic, sulfuric, phosphoric, acetic, glucuronic, citric, trichloroacetic, trifluoroacetic acid, their salts and combinations thereof, in a concentration range from about 0.1 mM to about 0.5M, and at least one biologically active substance selected from the group consisting of an antitumor agent, an anesthetic, an analgesic, an antimicrobial agent, a hormone, an antiasthmatic agent, a cardiac glycoside, an antihypertensive, a vaccine, an antiarrhythmic, an immunomodulator, a steroid, a monoclonal antibody, a neurotransmitter a radionuclide, a radio contrast agent, a nucleic acid, a protein, a herbicide, a pesticide, and suitable combinations thereof, said non-hydrohalic acid and biologically active substance being independently incorporated into either the lipid component or the first aqueous component, or into both,

(b) mixing the water-in-oil emulsion containing the non-hydrohalic acid with a second aqueous component to form solvent spherules; and thereafter

(c) removing the organic solvent from the solvent spherules to form multivesicular liposomes;

wherein the non-hydrohalic acid concentration in the water-in-oil emulsion is selected to provide controlled release of the biologically active substance from the liposomes.

2. The process of claim 1, wherein the acid is selected from the group consisting of sulfuric acid, phosphoric acid, and acetic acid, their salts, and combinations thereof, and wherein the controlled release is at physiologic conditions.

3. The process of claim 1, wherein the biologically active substance is cytarabine.

4. The process of claim 1, wherein the biologically active substance is amikacin.

5. The process of claim 1, wherein the biologically active substance is hydromorphone.

6. The process of claim 1, wherein the biologically active substance is leuprolide.

7. The process of claim 1, wherein the biologically active substance is insulin.

8. The process of claim 1, wherein the biologically active substance is interleukin-2.

9. The process of claim 1, wherein the biologically active substance is insulin-like growth factor-1.

10. The process of claim 1, wherein the controlled release of the biologically active substance is sufficient to ameliorate a disease following administration of the liposome to a living mammal.

11. The process of claim 1, wherein the biologically active substance is selected from the group consisting of herbicides and pesticides.

12. The process of claim 1, wherein the amphipathic lipid is provided in admixture with cholesterol, plant sterols, or combinations thereof.

13. The process of claim 1, wherein the amphipathic lipid is a zwitterionic lipid.

14. The process of claim 1, wherein the amphipathic lipid is an anionic lipid.

15. The process of claim 1, wherein the amphipathic lipid is a mixture of a zwitterionic lipid and an anionic lipid.

16. The process of claim 1, wherein the amphipathic lipid is a mixture of a zwitterionic lipid and a cationic lipid.

17. The process of claim 1, 13, 15, or 16, wherein the zwitterionic lipid is selected from the group consisting of phosphatidylcholines, phosphatidylethanolamines, sphingomyelins, lysophosphatidylcholines, lysophosphatidylethanolamines, and combinations thereof.

18. The process of claim 1, 14 or 15, wherein the anionic lipid is selected from the group consisting of phosphatidylglycerols, phosphatidylserines, phosphatidylinositols, phosphatidicacids, cardiolipins, and combinations thereof.

19. The process of claim 1 or 16, wherein the cationic lipid is selected from the group consisting of diacyl trimethylammonium propanes, diacyl dimethylammonium propanes, stearylamine, and combinations thereof.

20. The process of claim 1, wherein the neutral lipid is selected from the group consisting of triglycerides, diglycerides, ethylene glycols, squalene, and combinations thereof.

21. The process of claim 1, wherein the organic solvent is selected from the group consisting of ethers, hydrocarbons, halogenated hydrocarbons, halogenated ethers, esters, and combinations thereof.

22. The process of claim 1, wherein the emulsification of the two immiscible components is carried out using a method selected from the group consisting of mechanical agitation, ultrasonic energy agitation, and nozzle atomization.

23. The process of claim 1, wherein the formation of the solvent spherules is carried out using a method selected from the group consisting of mechanical agitation, ultrasonic energy agitation, and nozzle atomization.

24. The process of claim 1, wherein the removal of the organic solvent is by a method selected from the group consisting of sparging, rotary evaporation, passing gas over the solvent spherule suspension, solvent selective filtration, and combinations thereof.
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