Methods for making ultrasound contrast agents
Provided herein are improved methods for preparing phospholipid formulations including phospholipid UCA formulations.
1. A method for preparing a phospholipid suspension useful for preparing lipid-encapsulated gas microspheres comprising
forming a phospholipid solution that comprises (a) a DPPA, DPPC, and MPEG5000-DPPE phospholipid blend and propylene glycol, and (b) calcium and/or magnesium at a combined concentration of less than 0.7 ppm, wherein the phospholipid blend is formed in the presence of one or two but not all three of methanol, toluene and methyl t-butyl ether (MTBE), and
combining the phospholipid solution with an aqueous solution to form a phospholipid suspension.
2. The method of claim 1 , wherein the MPEG5000-DPPE comprises calcium and/or magnesium at a combined concentration of less than 115 ppm.
3. The method of claim 2 , wherein the phospholipid blend is formed in the presence of methanol.
4. The method of claim 2 , wherein the phospholipid blend is formed in the presence of toluene.
5. The method of claim 2 , wherein the phospholipid blend is formed in the presence of methanol and toluene.
6. The method of claim 2 , wherein the phospholipid blend is formed in the presence of MTBE.
7. The method of claim 1 , wherein the phospholipid blend is formed in the presence of methanol.
8. The method of claim 1 , wherein the phospholipid blend is formed in the presence of toluene.
9. The method of claim 1 , wherein the phospholipid blend is formed in the presence of methanol and toluene.
10. The method of claim 1 , wherein the phospholipid blend is formed in the presence of MTBE.
11. The method of claim 1 , wherein DPPA, DPPC and MPEG5000-DPPE are present in the phospholipid solution in a mole % ratio of 10 to 82 to 8 (10:82:8).
12. The method of claim 1 , wherein DPPA comprises calcium and/or magnesium at a combined concentration of less than 780 ppm, DPPC comprises calcium and/or magnesium at a combined concentration of less than 90 ppm, and propylene glycol comprises calcium and/or magnesium at a combined concentration of less than 0.7 ppm.
13. A method of ultrasound contrast imaging a subject comprising
preparing a phospholipid suspension according to claim 1 ,
activating the phospholipid suspension with a perfluorocarbon gas to form lipid-encapsulated gas microspheres,
administering the lipid-encapsulated gas microspheres to a subject, and
obtaining an ultrasound image of the subject.
14. The method of claim 13 , wherein the perfluorocarbon gas is perfluoropropane gas.
15. The method of claim 13 , wherein DPPA, DPPC and MPEG5000-DPPE are present in the phospholipid suspension in molar percentages of 5-15%, 77-90% and 5-15%, respectively.
16. The method of claim 13 , wherein the phospholipid suspension further comprises water, propylene glycol, one or more salts, and one or more buffers.
17. A method for preparing a phospholipid suspension useful for preparing lipid-encapsulated gas microspheres comprising
forming a phospholipid solution by individually combining DPPA, DPPC, and MPEG5000-DPPE with propylene glycol, wherein the phospholipid solution comprises calcium and/or magnesium at a combined concentration of less than 0.7 ppm, and
combining the phospholipid solution with an aqueous solution to form a phospholipid suspension.
18. A method of ultrasound contrast imaging a subject comprising
preparing a phospholipid suspension according to claim 17 ,
activating the phospholipid suspension with a perfluorocarbon gas to form lipid-encapsulated gas microspheres,
administering the lipid-encapsulated gas microspheres to a subject, and
obtaining an ultrasound image of the subject.
19. The method of claim 18 , wherein the perfluorocarbon gas is perfluoropropane gas.
20. The method of claim 18 , wherein DPPA, DPPC and MPEG5000-DPPE are present in the phospholipid suspension in molar percentages of 5-15%, 77-90% and 5-15%, respectively.
21. The method of claim 18 , wherein the phospholipid suspension further comprises water, propylene glycol, one or more salts, and one or more buffers.