Method for formulating large diameter synthetic membrane vesicles

A composition comprising a suspension of multivesicular liposomes in a suspending medium, said multivesicular liposomes having a structure including multiple non-concentric chambers and comprising at least one amphipathic lipid, at least one neutral lipid and a therapeutic agent:

• wherein said multivesicular liposomes are made by a process comprising removing an organic solvent from multivesicular liposome pre-droplets using an evaporation apparatus comprising:
• a solvent removal vessel having a top, a bottom and a circular wall;
• a rinse nozzle mounted to and extending through the top of the solvent removal vessel;
• a carrier gas entrance orifice;
• a solvent removal gas exit orifice centrally connected to the top and further comprising a gas outlet tube extending into the solvent removal vessel, wherein the gas outlet tube is fitted with a narrowing cone and the narrowing cone includes a tip through which gas residing in the solvent removal vessel enters the narrowing cone;
• a product exit orifice connected to the bottom of the vessel;
• and
• a product outlet pipe connected to the product exit orifice;
• at least one atomizing nozzle comprising:
• a first fluid conduit and a second fluid conduit each having at least one entrance orifice and at least one exit orifice;
• a fluid contacting chamber having a top comprising at least one entrance orifice and having a bottom comprising at least one exit orifice and said at least one entrance orifice connecting to the at least one exit orifice of the first fluid conduit and the at least one exit orifice of the second fluid conduit;
• a third fluid conduit, wherein the third fluid conduit annularly surrounds a portion of the fluid contacting chamber;
• wherein the organic solvent removal process comprises:
• introducing multivesicular liposome pre-droplets to the solvent removal vessel by the at least one atomizing nozzle, wherein the multivesicular liposome pre-droplets comprise a first component core and an aqueous phase shell, wherein the first component core comprises a suspension of first aqueous phase droplets suspended in a first organic phase;
• applying a carrier gas in a tangental direction to the circular wall through the carrier gas entrance orifice;
• removing a solvent removal gas through the solvent removal gas exit orifice to provide multivesicular liposomes in a first suspending medium and removing the formed multivesicular liposomes suspended in the first suspending medium through the product exit orifice through a product outlet pipe;
• and
• exchanging the first suspending medium by introducing the multivesicular liposomes in the first suspending medium into a continuous processing system to form a multivesicular liposomes suspension in the suspending medium, wherein the continuous processing system, comprises:
• a first concentrator unit comprising:
• a first retentate vessel;
• a first particle suspension inlet line, connected to the first retentate vessel and the product outlet pipe, wherein the process comprises applying the suspension of multivesicular liposomes in the first suspending medium from the product outlet pipe to the first particle suspension inlet line;
• a first particle suspension outlet line, connecting the first retentate vessel and a first hollow fiber tangential flow filter;
• a first solution inlet line supplying a second suspending medium;
• a first sterilizing hydrophilic filter, connecting the first retentate vessel and the first solution inlet line;
• a first pump located along the first particle suspension outlet line between the first retentate vessel and the first hollow fiber tangential flow filter;
• a first retentate line between the first hollow fiber tangential flow filter and the first retentate vessel;
• a second particle suspension outlet line, leading to a second concentrator unit,
• said second concentrator unit comprising:
• a second retentate vessel;
• a second particle suspension inlet line, connected to the second retentate vessel and the second particle suspension outlet line;
• a third particle suspension outlet line, connecting the second retentate vessel and a second hollow fiber tangential flow filter;
• a second solution inlet line supplying a third suspending medium;
• a second sterilizing hydrophilic filter, connecting the second retentate vessel and the second solution inlet line;
• and
• a second pump located along the third particle suspension outlet line between the second retentate vessel and the second hollow fiber tangential flow filter;
• a second retentate line between the second hollow fiber tangential flow filter and the second retentate vessel;
• and
• optionally a fourth particle suspension outlet line,
• wherein the at least one amphipathic lipid is selected from the group consisting of phosphatidylcholines, phosphatidylserines, phosphatidylethanolamines, phosphatidylinositols, sphingomyelin, soybean lecithin (soya lecithin), egg lecithin, lysophosphatidylcholines, lysophosphatidylethanolamines, phosphatidylglycerols, phosphatidic acids, cardiolipins, acyl trimethylammonium propane, diacyldimethylammonium propane, stearylamine, and ethyl phosphatidylcholine, and
• wherein the at least one neutral lipid is selected from the group consisting of glycerol esters, glycol esters, tocopherol esters, sterol esters, hydrocarbons and squalenes.