Methods for preparation of lipid-encapsulated therapeutic agents

Abstract

Fully lipid-encapsulated therapeutic agent particles of a charged therapeutic agent are prepared by combining a lipid composition containing preformed lipid vesicles, a charged therapeutic agent, and a destabilizing agent to form a mixture of preformed vesicles and therapeutic agent in a destabilizing solvent. The destabilizing solvent is effective to destabilize the membrane of the preformed lipid vesicles without disrupting the vesicles. The resulting mixture is incubated for a period of time sufficient to allow the encapsulation of the therapeutic agent within the preformed lipid vesicles. The destabilizing agent is then removed to yield fully lipid-encapsulated therapeutic agent particles. The preformed lipid vesicles comprise a charged lipid which has a charge which is opposite to the charge of the charged therapeutic agent and a modified lipid having a steric barrier moiety for control of aggregation.

1 .- 12 . (canceled)  
     
     
         13 . A therapeutic agent particle comprising a charged therapeutic agent, a charged lipid having a charge which is opposite to that of the charged therapeutic agent, and a modified lipid having a steric barrier moiety, wherein the therapeutic agent is fully encapsulated and wherein the therapeutic agent particle comprises two or more lipid bilayers.  
     
     
         14 . The therapeutic agent particle of claim  1 , wherein the therapeutic agent is anionic and the charged lipid is cationic.  
     
     
         15 . The therapeutic agent particle of claim  2 , wherein the therapeutic agent is a polynucleotide.  
     
     
         16 . The therapeutic agent particle of  claim 14 , wherein the cationic charged lipid is selected from the group consisting of: DODAC, DOTMA, DDAB, DOTAP, DC-Chol, DMRIE, DOSPA, DOGS, DODMA, and DODAP.  
     
     
         17 . The therapeutic agent particle of claim  1 , wherein the therapeutic agent is cationic and the charged lipid is anionic.  
     
     
         18 . The therapeutic agent particle of claim  1 , wherein the modified lipid having a steric barrier moiety is a PEG-lipid or a polyamide oligomer lipid.  
     
     
         19 . The therapeutic agent particle of claim  1 , wherein the lipid composition of the particle comprises 10-40 mol % charged lipid and 0.5 to 15 mol % modified lipid.  
     
     
         20 . The therapeutic agent particle of claim  1 , further comprising a neutral lipid and a sterol.  
     
     
         21 . The therapeutic agent particle of  claim 20 , wherein the lipid composition of the particle comprises 10-40 mol % charged lipid, 25-45 mol % neutral lipid, 35-55 mol % sterol, and 0.5-15 mol % modified lipid.  
     
     
         22 . The therapeutic agent particle of claim  1 , wherein the particle size is 25-250 nm diameter.  
     
     
         23 . A pharmaceutical composition comprising therapeutic agent particles of any of claims  13 - 22 .  
     
     
         24 . The composition of  claim 23 , wherein at least 50% of the therapeutic agent particles in the composition comprise two or more lipid bilayers.