Claims for Patent: 5,976,501

Summary for Patent: 5,976,501

Title:	Use of pressure resistant protein microspheres encapsulating gases as ultrasonic imaging agents for vascular perfusion
Abstract:	Conventional ultrasonic imaging methods are described which involve the use of aqueous suspension of microspheres. These microspheres are further characterized as consisting of gas cores encapsulated by a protein shell which are formed in the presence of perfluoroalkane vapors. The presence of the vapor during formation changes the shell characteristics and thus protects the gas from being solubilized in the surrounding aqueous environment. In addition, the presence of the perfluoroalkane vapor during formation may also provide improved echogenic properties for vascular imaging applications.
Inventor(s):	Jablonski; Edward G. (Escondido, CA)
Assignee:	Molecular Biosystems, Inc. (San Diego, CA)
Application Number:	08/665,028
Patent Claims:	1. A method of imaging a tissue or organ of a subject comprising the steps of: (a) administering to said subject a suspension of microspheres comprising a gas core encapsulated by a shell of heat-insolubilized protein, wherein said microspheres are formed by contacting a heat-insolubilizable protein with a gas phase comprising a gas and a heated perfluoroalkane vapor; (b) waiting for a sufficient length of time for said microspheres to reach said tissue or organ and perfuse therein; (c) applying ultrasonic energy to said subject; and (d) generating an ultrasonic image from said ultrasonic energy reflected from said tissue or organ. 2. The method of claim 1 wherein said tissue or organ is a heart having a myocardium and a left and right ventricular cavity, and step (b) further comprises waiting for a sufficient length of time for said microspheres to reach said heart, fill said left ventricular cavity, perfuse said myocardium, exit said left ventricular cavity, and exit said myocardium. 3. The method of claim 1 wherein said gas has a solubility greater than or equal to 0.01 mL of gas per mL of water at 25.degree. C. at 1 atmosphere pressure. 4. The method of claim 3 wherein said gas is air. 5. The method of claim 1 wherein said perfluoroalkane vapor is perfluoropentane vapor. 6. The method of claim 5 wherein said protein is albumin. 7. The method of claim 5 wherein said perfluoropentane vapor is between about 20% to 50% (v/v) of said gas phase. 8. The method of claim 7 wherein said perfluoropentane vapor is 50% of said gas phase and said protein is albumin. 9. The method of claim 8 wherein said gas is air. 10. The method of claim 1 wherein said perfluoroalkane vapor is perfluorohexane vapor. 11. The method of claim 10 wherein said protein is albumin. 12. The method of claim 10 wherein said perfluorohexane vapor is between about 10% to 20% (v/v) of said gas phase. 13. The method of claim 1 wherein said perfluoroalkane vapor is perfluoroheptane vapor. 14. The method of claim 13 wherein said protein is albumin. 15. The method of claim 13 wherein said perfluoroheptane vapor is between about 7% to 15% of said gas phase. 16. The method of claim 1 wherein said microspheres are present in said suspension in a concentration of between 1.times.10.sup.7 to 1.times.10.sup.10 microspheres per mL of suspension. 17. The method of claim 1 wherein said microsphere suspension is administered intravenously as a bolus injection. 18. The method of claim 1 wherein said microsphere suspension is administered intravenously over a period of at least 1 minute. 19. The method of claim 1 wherein step (d) further comprises generating a two-dimensional ultrasonic image. 20. The method of claim 1 wherein step (d) further comprises generating a three-dimensional ultrasonic image. 21. The method of claim 1 wherein step (c) further comprises applying continuous ultrasonic energy. 22. The method of claim 1 wherein step (c) further comprises applying pulsed ultrasonic energy. 23. The method of claim 1 wherein step (a) further comprises administering said microsphere suspension from a pre-filled syringe. 24. The method of claim 1 wherein said gas has a solubility less than 0.01 mL per mL of water at 25.degree. C. and 1 atmosphere pressure. 25. The method of claim 24 wherein said gas is perfluoropropane. 26. A process for making microspheres useful as ultrasonic imaging agents having a gas core encapsulated by a shell of a heat-insolubilized protein comprising the steps of: (a) mixing a gas phase comprising a gas and perfluoroalkane vapor which has been heated to a temperature above its boiling point and close to the denaturation temperature of the protein with a solution of a heat-insolubilizable protein; (b) cavitating said mixture under conditions which form microspheres by heat-insolubilizing said protein; and (c) cooling said microspheres to condense at least a portion of said perfluoroalkane into said shell. 27. The process of claim 26 wherein said gas has a solubility greater than or equal to 0.01 mL per mL of water at 25.degree. C. at 1 atmosphere pressure. 28. The process of claim 27 wherein said gas is air. 29. The process of claim 26 wherein said protein is albumin. 30. The process of claim 26 wherein said perfluoroalkane vapor is perfluoropentane vapor. 31. The process of claim 30 wherein said perfluoropentane vapor is between about 20% to 50% (v/v) of said gas phase. 32. The process of claim 30 wherein said perfluoropentane vapor is 50% of said gas phase and said protein is albumin. 33. The process of claim 32 wherein said gas is air. 34. The process of claim 26 wherein said perfluoroalkane vapor is perfluorohexane vapor. 35. The process of claim 34 wherein said perfluorohexane vapor is between about 10% to 20% (v/v) of said gas phase. 36. The process of claim 26 wherein said perfluoroalkane vapor is perfluoroheptane vapor. 37. The process of claim 36 wherein said perfluoroheptane vapor is between about 7% to 15% of said gas phase. 38. The process of claim 29 wherein said albumin is present in said solution of said protein at a concentration of 1% to 5% by weight, inclusive. 39. The process of claim 26 wherein said cavitation occurs by applying ultrasonic energy. 40. The process of claim 26 wherein said cavitation occurs by applying mechanical energy. 41. A composition for use as an ultrasound imaging agent comprising a suspension of microspheres, said microspheres comprising a gas core encapsulated by a protein shell, wherein said microspheres are formed in the presence of a gas phase comprising a gas and a heated perfluoroalkane vapor. 42. The composition of claim 41 wherein said gas has a solubility greater than or equal to 0.01 mL of gas per mL of water at 25.degree. C. at 1 atmosphere pressure. 43. The composition of claim 41 wherein said gas is air. 44. The composition of claim 41 wherein said protein is albumin. 45. The composition of claim 41 wherein said perfluoroalkane vapor is perfluoropentane vapor. 46. The composition of claim 45 wherein said perfluoropentane vapor is between 20% to 50% (v/v) of said gas phase. 47. The composition of claim 46 wherein said perfluoropentane vapor is 50% of said gas phase and said protein is albumin. 48. The composition of claim 47 wherein said gas is air. 49. The composition of claim 41 wherein said perfluoroalkane vapor is perfluorohexane vapor. 50. The composition of claim 49 wherein said perfluorohexane vapor is between about 10% to 20% (v/v) of said gas phase. 51. The composition of claim 41 wherein said perfluoroalkane vapor is perfluoroheptane vapor. 52. The composition of claim 51 wherein said perfluoroheptane vapor is between about 7% to 15% of said gas phase. 53. The composition of claim 41 wherein said microspheres exhibit pressure resistance at 10 psi. 54. The composition of claim 44 wherein said albumin is human serum albumin. 55. The composition of claim 41 wherein said microspheres have a mean diameter in the range of 0.1 and 10 microns. 56. The composition of claim 41 wherein said microspheres are present in said suspension at a concentration of from 1.times.10.sup.7 to 1.times.10.sup.10 microspheres per mL of suspension. 57. The composition of claim 41 wherein said microspheres have a mean diameter in the range of 1 to 5 microns. 58. The composition of claim 41 wherein said shell is modified to include moieties that target a specific tissue or organ. 59. A composition for use as an ultrasound imaging agent comprising a suspension of microspheres, said microspheres comprising a gas phase of 50% gas and 50% perfluoropentane (v/v) encapsulated by a shell of heat-insolubilized protein. 60. The composition of claim 59 wherein said gas is air.

Details for Patent 5,976,501

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Grifols Therapeutics Llc	ALBUKED, PLASBUMIN-20, PLASBUMIN-25, PLASBUMIN-5	albumin (human)	For Injection	101138	10/21/1942		2040-01-28
Baxalta Us Inc.	BUMINATE, FLEXBUMIN	albumin (human)	Injection	101452	03/03/1954		2040-01-28
Csl Behring Ag	ALBURX	albumin (human)	Injection	102366	07/23/1976		2040-01-28
Grifols Biologicals Llc	ALBUTEIN	albumin (human)	Injection	102478	08/15/1978		2040-01-28
Instituto Grifols, S.a.	HUMAN ALBUMIN GRIFOLS	albumin (human)	Injection	103352	02/17/1995		2040-01-28