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Claims for Patent: 6,110,503

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Claims for Patent: 6,110,503

Title: Preparation of biodegradable, biocompatible microparticles containing a biologically active agent
Abstract:A method for preparing biodegradable, biocompatible microparticles. A first phase is prepared that includes a biodegradable, biocompatible polymer, an active agent, and a solvent. An immiscible second phase is prepared. The first and second phases are combined to form an emulsion in which the first phase is discontinuous and the second phase is continuous. The two phases are immersed in a quench liquid that includes a quench medium and a quantity of the solvent. The quantity of the solvent is selected to control a rate of extraction of the solvent from the first phase. The first phase is isolated in the form of microparticles. Also disclosed is a microencapsulated active agent prepared by the method for preparing biodegradable, biocompatible microparticles.
Inventor(s): Rickey; Michael E. (Loveland, OH), Ramstack; J. Michael (Lebanon, OH), Lewis; Danny H. (Hartselle, AL)
Assignee: Alkermes Controlled Therapeutics Inc. (Cambridge, MA)
Application Number:09/263,098
Patent Claims: 1. A microencapsulated active agent prepared by a method of preparing biodegradable, biocompatible microparticles, said method comprising:

(A) preparing a first phase, said first phase comprising an active agent, a biodegradable, biocompatible polymer, and a solvent blend comprising a first solvent and a second solvent;

(B) preparing a second phase, wherein said first phase is substantially immiscible in said second phase;

(C) combining said first phase and said second phase under the influence of mixing means to form an emulsion in which said first phase is discontinuous and said second phase is continuous;

(D) immersing said first phase and said second phase in a quench liquid that comprises a quench medium and a quantity of said first solvent, wherein said first solvent has a rate of extraction from said discontinuous first phase that is more rapid than a rate of extraction from said discontinuous first phase of said second solvent, said quench liquid being free from said second solvent;

(E) isolating said discontinuous first phase in the form of microparticles; and

(F) adjusting a temperature of said quench medium to control solubility of said first solvent in said quench medium.

2. A method for preparing microparticles, comprising:

(A) preparing a first phase comprising a biodegradable and biocompatible polymer, an active agent, and a solvent;

(B) preparing a second phase;

(C) combining said first phase and said second phase under the influence of mixing means to form an emulsion in which said first phase is discontinuous and said second phase is continuous;

(D) separating said discontinuous first phase from said continuous second phase; and

(E) reducing a residual level of said solvent in said discontinuous first phase to less than about 2% by weight.

3. The method of claim 2, wherein step (E) comprises:

washing said discontinuous first phase with an aqueous solution at a temperature in the range of from about 25.degree. C. to about 40.degree. C.

4. The method of claim 2, wherein step (E) comprises:

washing said discontinuous first phase with an aqueous solvent system comprising water and a second solvent for said solvent.

5. The method of claim 2, wherein said solvent is a solvent blend of at least two mutually miscible organic solvents.

6. The method of claim 2, wherein said active agent comprises at least one basic moiety.

7. The method of claim 3, wherein said aqueous solution comprises water and a C.sub.1 -C.sub.4 alcohol.

8. The method of claim 7, wherein said C.sub.1 -C.sub.4 alcohol is ethanol.

9. The method of claim 3, wherein said aqueous solution is water.

10. The method of claim 4, wherein said aqueous solvent system further comprises a C.sub.1 -C.sub.4 alcohol.

11. The method of claim 10, wherein said C.sub.1 -C.sub.4 alcohol is ethanol.

12. A microencapsulated active agent prepared by a method for preparing microparticles, said method comprising:

(A) preparing a first phase comprising a biodegradable and biocompatible polymer, an active agent, and a solvent;

(B) preparing a second phase;

(C) combining said first phase and said second phase under the influence of mixing means to form an emulsion in which said first phase is discontinuous and said second phase is continuous;

(D) separating said discontinuous first phase from said continuous second phase; and

(E) reducing a residual level of said solvent in said discontinuous first phase to less than about 2% by weight.

13. The microencapsulated active agent of claim 12, wherein step (E) comprises:

washing said discontinuous first phase with an aqueous solution at a temperature in the range of from about 25.degree. C. to about 40.degree. C.

14. The microencapsulated active agent of claim 12, wherein step (E) comprises:

washing said discontinuous first phase with an aqueous solvent system comprising water and a second solvent for said solvent.

15. The microencapsulated active agent of claim 12, wherein said solvent is a solvent blend of at least two mutually miscible organic solvents.

16. The microencapsulated active agent of claim 12, wherein said active agent comprises at least one basic moiety.

17. The microencapsulated active agent of claim 13, wherein said aqueous solution comprises water and a C.sub.1 -C.sub.4 alcohol.

18. The microencapsulated active agent of claim 17, wherein said C.sub.1 -C.sub.4 alcohol is ethanol.

19. The microencapsulated active agent of claim 13, wherein said aqueous solution is water.

20. The microencapsulated active agent of claim 14, wherein said aqueous solvent system further comprises a C.sub.1 -C.sub.4 alcohol.

21. The microencapsulated active agent of claim 20, wherein said C.sub.1 -C.sub.4 alcohol is ethanol.

22. The microencapsulated active agent of claim 12, wherein said second phase comprises an aqueous solution of a hydrophilic colloid.

23. The microencapsulated active agent of claim 12, wherein said second phase comprises an aqueous solution of a surfactant.

24. The microencapsulated active agent of claim 12, wherein said second phase is water.

25. The microencapsulated active agent of claim 12, wherein said solvent is free from halogenated hydrocarbons.

26. The microencapsulated active agent of claim 12, wherein said mixing means comprises a static mixer.

27. The method of claim 2, wherein said mixing means comprises a static mixer.

28. The method of claim 2, wherein said active agent is a psychotherapeutic agent.

29. The microencapsulated active agent of claim 12, wherein said active agent is a psychotherapeutic agent.
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