Methods and apparatus for making liposomes

DETAILED DESCRIPTION The present invention features methods and apparatus for producing liposomes.
The methods and apparatus are suitable for large scale production of pharmaceutical grade liposomes which are sterile, of a predetermined size, and are substantially free of organic solvents.
The present invention features several different methods of making liposomes using critical, supercritical or near critical fluids.
As used herein, the term "phospholipid" refers to compositions which are esters of fatty acids in which the alcohol component of the molecule contains a phosphate group as an integral part.
Phospholipids comprise the glycerophosphatides, containing glycerol, and the sphingomyelins containing sphingosine.
In the field of physical chemistry, the term "critical fluid" refers to a gas at its critical temperatures and at its critical pressures.
The term "supercritical fluid" refers to a gas above its critical temperature and above its critical pressure.
Supercritical fluids are sometimes designated in this application by the abbreviation "SCF".
The term "near critical" is used in the sense of approaching or close to being critical.
One example, without limitation, of a near critical fluid is a gas having a temperature below its critical temperature and a pressure at or above the critical pressure.
Such gas has properties which, may approach those of a supercritical or critical fluid, particularly in solvating properties.
In industrial settings where critical, supercritical and near critical fluids are used, it is common, particularly where the solvent properties are being applied, to use the term "critical" to refer to supercritical, critical and near critical fluids.
This application will use the term "SCoCoNC fluid" to represent supercritical, critical or near critical fluids.
The use of the term "critical" with respect to liposomes and liposome formation refers to liposomes formed with supercritical fluid and near critical fluids as well as critical fluid.
Fluids are sometimes referred to in the examples as "critical" as a convenience, even though such fluids may be supercritical, critical or near critical