Methods of preparing gas-filled liposomes

• US 5,715,824 A
• Filed: 06/06/1995
• Issued: 02/10/1998
• Est. Priority Date: 12/22/1989
• Status: Expired due to Term

• Current Assignee: Lantheus Medical Imaging, Inc. (Lantheus Holdings, Inc.)
• Original Assignee: Imarx Pharmaceutical Corp. (Sycamore Entertainment Group, Inc.)
• Inventors: Ramaswami, VaradaRajan, Yellowhair, David, Matsunaga, Terry, Fritz, Thomas A., Unger, Evan C., Wu, Guanli
• Primary Examiner(s): JAWORSKI, FRANCIS J
• Application Number:
  US08/471,250
• Time in Patent Office: 980 Days
• Field of Search: 128/662.02, 264/4, 264/3, 264/4.1, 424/9
• US Class Current: 424/9.51
• CPC Class Codes: A61K 41/0028 Disruption, e.g. by heat or ultrasounds, sonophysical or sonochemical activation, e.g. thermosensitive or heat-sensitive liposomes, disruption of calculi with a medicinal preparation and ultrasounds
• CPC Class Codes: A61K 41/0052 Thermotherapy; Hyperthermia; Magnetic induction; Induction heating therapy
• CPC Class Codes: A61K 47/6925 the form being a microcapsule, nanocapsule, microbubble or nanobubble
• CPC Class Codes: A61K 49/1815 compo-inhalant, e.g. breath tests
• CPC Class Codes: A61K 49/22 Echographic preparations; Ultrasound imaging preparations ; Optoacoustic imaging preparations
• CPC Class Codes: A61K 49/223 Microbubbles, hollow microspheres, free gas bubbles, gas microspheres
• CPC Class Codes: A61K 49/227 Liposomes, lipoprotein vesicles, e.g. LDL or HDL lipoproteins, micelles, e.g. phospholipidic or polymeric
• CPC Class Codes: A61K 9/127 Liposomes
• CPC Class Codes: A61K 9/1277 Processes for preparing; Proliposomes
• CPC Class Codes: A61K 9/1278 Post-loading, e.g. by ion or pH gradient
• CPC Class Codes: A61M 5/3145 Filters incorporated in syringes
• CPC Class Codes: Y10S 977/795 Composed of biological material
• CPC Class Codes: Y10S 977/801 Drug
• CPC Class Codes: Y10S 977/905 Specially adapted for travel through blood circulatory system
• CPC Class Codes: Y10S 977/906 Drug delivery
• CPC Class Codes: Y10S 977/907 Liposome
• CPC Class Codes: Y10S 977/927 Diagnostic contrast agent
• CPC Class Codes: Y10S 977/929 Ultrasound contrast agent
• CPC Class Codes: Y10S 977/962 for carrying or transporting

Abstract

Methods of and apparatus for preparing gas-filled liposomes are described. Gas-filled liposomes prepared by these methods are particularly useful, for example, in ultrasonic imaging applications and in therapeutic drug delivery systems.

Claims

1. An apparatus for making gas-filled liposomes, comprising:

a) a vessel;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel; and

d) means for converting at least a major portion of said aqueous solution into a foam by instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel.

2. The apparatus according to claim 1, wherein said means for introducing an aqueous lipid solution comprises means for introducing dried lipids and means for introducing an aqueous media into said vessel.

3. The apparatus according to claim 2, wherein said means for introducing an aqueous lipid solution further comprises means for introducing a therapeutic compound into said vessel.

4. The apparatus according to claim 1, wherein said means for instilling said gas into said aqueous solution comprises means for shaking said aqueous solution.

5. The apparatus according to claim 4, wherein said means for shaking said aqueous solution comprises means for shaking said vessel.

6. The apparatus according to claim 4, wherein said means for shaking said aqueous solution comprises means for vortexing said aqueous solution.

7. The apparatus according to claim 1, further comprising means for cooling said aqueous solution.

12. The apparatus according to claim 1, further comprising means for sizing said gas-filled liposomes.

13. The apparatus according to claim 1, further comprising a filter in flow communication with said vessel.

14. The apparatus according to claim 1, further comprising means for pressurizing said vessel.

15. The apparatus according to claim 1, further comprising means for drawing said gas-filled liposomes produced from said vessel into a syringe substantially without further processing.

23. The apparatus of claim 1 wherein said vessel is a barrel of a syringe.

24. The apparatus of claim 23 wherein said syringe also comprises at least one filter and a needle;

further comprising a means for extracting comprising means for sizing said gas-filled liposomes by extruding said liposomes from said barrel through said filter.

8. An apparatus for making gas-filled liposomes, comprising:

a) a vessel;

b) means for introducing an aqueous solution comprising a lipid into said vessel

c) means for introducing a gas into said vessel; and

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel; and

e) means for sizing said gas-filled liposomes while extracting said foam from said vessel.

10. The apparatus according to claim 8, further comprising means for flowing said gas-filled liposomes extracted through a filter assembly.

11. The apparatus according to claim 10, wherein said filter assembly comprises first and second filters spaced a predetermined distance apart.

9. An apparatus for making gas-filled liposomes, comprising:

a) a vessel;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel; and

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel; and

e) means for extracting said foam from said vessel;

said means for extracting said foam from said vessel having means for adjusting the vertical location at which said foam is extracted from said vessel so as to regulate the size of said liposomes extracted.

16. Gas-filled liposomes comprised of lipids having a gel to liquid crystalline phase transition temperature below room temperature and made by a method comprising the steps of:

a) cooling an aqueous solution of said lipids below said transition temperature;

b) instilling a gas into said aqueous solution; and

c) shaking said cooled aqueous solution so as to produce a foam containing said gas-filled liposomes.

17. The gas-filled liposomes of claim 16 comprising at least one lipid selected from the group consisting of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylethanolamine, and a phophatidic acid, and said liposome further comprising polyethylene glycol.

18. The gas-filled liposomes of claim 16 comprising at least one dipalmitoyl lipid.

19. The gas-filled liposomes of claim 16 having a phase transition temperature greater than about 20°

C.

20. The gas-filled liposomes of claim 16 for use with a nebulizer, said liposomes targeted to the lung.

21. The gas-filled liposomes of claim 16 comprising dipalmitoylphosphatidylethanolamine, said liposome further comprising polyethylene glycol.

39. Gas-filled liposomes of claim 16 wherein said liposomes have one lipid layer.

40. Gas-filled liposomes of claim 16 wherein said liposomes have more than one lipid layer.

22. An apparatus for making gas-filled liposomes, comprising:

a) a syringe comprising a barrel, said barrel forming a vessel, said syringe also comprising at least one filter and a needle;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel;

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel; and

e) means for extracting said foam from said vessel, said means for extracting comprising means for sizing said gas-filled liposomes by extruding said liposomes from said barrel through said filter.

25. An apparatus for making gas-filled liposomes, comprising:

a) a syringe comprising a barrel, said barrel forming a vessel, said syringe also comprising at least one filter and a needle;

whereby said filter is a means for sizing said liposomes upon drawing said liposomes into said barrel;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel; and

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel.

26. An apparatus for making gas-filled liposomes, comprising:

a) syringe comprising a barrel, said barrel forming a vessel, said syringe also comprising at least one filter and a needle;

whereby said filter is a means for sizing said liposomes upon extruding said liposomes from said barrel;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel;

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel; and

e) means for extracting said foam from said vessel.

27. The apparatus of claim 26 having a first filter and a second filter, said first filter and said second filter having pores, said second filter having a pore size of about 10 μ

m and said first filter having a pore size of about 8 μ

m.

28. The apparatus of claim 26, wherein said filter has pores, said pores having a size in the range of about 30 nm to about 20 microns.

29. The apparatus of claim 26, wherein said filter has pores, said pores having a size of about 8 μ

m.

30. An apparatus for making gas-filled liposomes, comprising:

a) a vessel;

b) means for introducing an aqueous solution comprising a lipid into said vessel;

c) means for introducing a gas into said vessel; and

d) means for instilling said gas into said aqueous solution in said vessel, thereby producing a foam containing gas-filled liposomes within said vessel;

e) means for extracting said foam from said vessel, said means for extracting comprises means for drawing said gas-filled liposome-containing foam into a syringe, said syringe comprising a barrel, at least one filter, and a needle;

thereby sizing said liposomes.

31. The apparatus of claim 30 having a first filter and a second filter, said first filter and said second filter having pores, said second filter having a pore size of about 10 μ

m and said first filter having a pore size of about 8 μ

m.

32. The apparatus of claim 30, wherein said filter has pores, said pores having a size in the range of about 30 nm to about 20 microns.

33. The apparatus of claim 30, wherein said filter has pores, said pores having a size of about 8 μ

m.

34. A gas-filled liposome apparatus comprising a syringe having a barrel, a filter assembly, and a needle, said filter assembly fitted between said barrel and said needle and comprising at least one filter, said barrel containing a gas-filled liposomes prepared by a gel state shaking gas instillation method.

35. The apparatus of claim 34 wherein said filter assembly is a cascade filter assembly comprising a first filter, having a needle-facing side and a barrel-facing side, a second filter, first and second metallic mesh discs on said needle-facing and said barrel-facing sides of said first filter respectively, an O-ring between said second metallic mesh disc and said second filter, and wherein said second filter is spaced about 150 μ

m from the barrel-facing side of said first filter.

36. The apparatus of claim 35, said first filter and said second filter having pores, said second filter having a pore size of about 10 μ

m and said first filter having a pore size of about 8 μ

m.

37. The apparatus of claim 34, wherein said filter has pores, said pores having a size in the range of about 30 nm to about 20 microns.

38. The apparatus of claim 34, wherein said filter has pores, said pores having a size of about 8 μ

m.