Preparation of a lipid blend and a phospholipid suspension containing the lipid blend

Abstract

The present invention describes processes for the preparation of a lipid blend and a uniform filterable phospholipid suspension containing the lipid blend, such suspension being useful as an ultrasound contrast agent.

1 - 44 . (canceled) 
     
     
         45 . A lipid suspension prepared according to a process comprising:
 (a) contacting phospholipids with a first non-aqueous solvent which causes the phospholipids to dissolve and form a lipid solution, wherein contacting comprises (a) sequential addition of the individual phospholipids to the first non-aqueous solvent or (b) combining the phospholipids with each other prior to their addition to the first non-aqueous solvent;   (b) contacting the non-aqueous lipid solution of (a) with a second non-aqueous solvent which causes the phospholipids to precipitate out as a solid lipid blend;   (c) collecting the solid lipid blend;   (d) contacting the solid lipid blend with a third non-aqueous solvent which causes the lipid blend to dissolve to form a lipid blend solution;   (e) contacting the lipid blend solution with an aqueous solution to yield a lipid suspension comprising the third non-aqueous solvent,   wherein the phospholipids are 1,2-dipalmitoyl-sn-glycero-3-phosphotidic acid, mono sodium salt (DPPA), 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), and N-(methoxypolyethylene glycol 5000 carbamoyl)-1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine, mono sodium salt (MPEG5000-DPPE).   
     
     
         46 . The lipid suspension of  claim 45 , wherein the first non-aqueous solvent is a mixture of methanol and toluene. 
     
     
         47 . The lipid suspension of  claim 45 , wherein the second non-aqueous solvent is methyl t-butyl ether. 
     
     
         48 . The lipid suspension of  claim 45 , wherein the third non-aqueous solvent is propylene glycol. 
     
     
         49 . The lipid suspension of  claim 45 , wherein the aqueous solution contains water, saline, a saline and glycerin mixture, or a saline and glycerin and non-aqueous solvent mixture. 
     
     
         50 . The lipid suspension of  claim 45 , wherein the aqueous solution contains a saline, glycerin, and propylene glycol mixture. 
     
     
         51 . The lipid suspension of  claim 45 , wherein the first non-aqueous solvent contains a mixture of methanol and toluene and wherein the second non-aqueous solvent is methyl t-butyl ether. 
     
     
         52 . The lipid suspension of  claim 45 , wherein the third non-aqueous solvent is propylene glycol and wherein the aqueous solution contains a saline, glycerin, and propylene glycol mixture. 
     
     
         53 . The lipid suspension of  claim 50 , wherein sodium chloride, glycerin, propylene glycol, and about 0.75 to 1.0 mg/mL of the lipid blend are present in the lipid suspension. 
     
     
         54 . The lipid suspension of  claim 45 , wherein the third non-aqueous solvent is heated to a temperature of about 30 to 70° C. prior to contacting with the solid lipid blend. 
     
     
         55 . The lipid suspension of  claim 45 , wherein the third non-aqueous solvent is heated to a temperature of about 50 to 55° C. prior to contacting with the solid lipid blend. 
     
     
         56 . The lipid suspension of  claim 45 , wherein in step (d) the ratio of solid lipid blend to third non-aqueous solvent is from about 5 mg of solid lipid blend per mL of non-aqueous solvent to about 15 mg of solid lipid blend per mL of non-aqueous solvent. 
     
     
         57 . The lipid suspension of  claim 45 , wherein in step (e), the aqueous solution is heated to a temperature of about 45 to 60° C. prior to contacting with the lipid blend solution. 
     
     
         58 . The lipid suspension of  claim 57 , wherein the aqueous solution is heated to a temperature of about 50 to 55° C. prior to contacting with the lipid blend solution. 
     
     
         59 . The lipid suspension of  claim 45 , wherein the lipid suspension is filtered through at least one sterilizing filter. 
     
     
         60 . The lipid suspension of  claim 59 , wherein the lipid suspension is filtered through two sterilizing filters. 
     
     
         61 . The lipid suspension of  claim 59 , wherein the lipid suspension is dispensed into a vial. 
     
     
         62 . The lipid suspension of  claim 61 , wherein the headspace gas of the vial is exchanged with a perfluorocarbon gas. 
     
     
         63 . The lipid suspension of  claim 62 , wherein the perfluorocarbon gas is perfluoropropane. 
     
     
         64 . The lipid suspension of  claim 62 , wherein the vial is sterilized. 
     
     
         65 . The lipid suspension of  claim 64 , wherein the vial is sterilized at about 126-130° C. for 1 to 10 minutes. 
     
     
         66 . The lipid suspension of  claim 45 , wherein
 (i) the first non-aqueous solvent is a mixture of methanol and toluene;   (ii) the second non-aqueous solvent is methyl t-butyl ether;   (iii) the third non-aqueous solvent is propylene glycol;   (iv) the aqueous solution contains a saline and glycerin and non-aqueous solvent mixture;   (v) the third non-aqueous solvent is heated to a temperature of about 50-60° C. prior to contacting with the solid lipid blend;   (vi) in step (d) the ratio of solid lipid blend to third non-aqueous solvent is from about 5 mg of solid lipid blend per mL of non-aqueous solvent to about 15 mg of solid lipid blend per mL of non-aqueous solvent.   
     
     
         67 . The lipid suspension of  claim 45 , wherein the lipid suspension further comprises:
 sodium chloride;   glycerin;   propylene glycol; and   water.   
     
     
         68 . The lipid suspension of  claim 67 , wherein sodium chloride, glycerin, propylene glycol, and about 0.75 to 1.0 mg/mL of the lipid blend are present in the lipid suspension. 
     
     
         69 . The lipid suspension of  claim 68 , wherein 1,2-dipalmitoyl-sn-glycero-3-phosphotidic acid, mono sodium salt (DPPA), 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), and N-(methoxypolyethylene glycol 5000 carbamoyl)-1,2-dipalmitoyl-sn-glycero-3-phosphatidylethanolamine, mono sodium salt (MPEG5000-DPPE) are present in a mole ratio of 10% to 82% to 8%. 
     
     
         70 . The lipid suspension of  claim 67 , wherein sodium chloride is present in an amount of about 6.8 mg/mL. 
     
     
         71 . The lipid suspension of  claim 67 , wherein glycerin is present in an amount of about 0.1 mL/mL. 
     
     
         72 . The lipid suspension of  claim 67 , wherein propylene glycol is present in an amount of about 0.1 mL/mL. 
     
     
         73 . A method comprising
 using the lipid suspension of  claim 45 , together with a perfluorocarbon gas, as an ultrasound contrast agent.