Process for the preparation of liposomes

Claim 1

A process for the preparation of synthetic liposomes, including the steps of dispersing a first aqueous liquid with the aid of ultrasonic vibration in a carrier liquid which is insoluble in water or only slightly soluble in water and has a density less than that of water, in the presence of at least one compound of the general formula XY, where X represents a hydrophilic polar group and Y represents a hydrophobic non-polar group, selected from the group consisting of phospholipids and lipid-like substances in which the hydrophilic polar group X is selected from phosphato, carboxylic, sulphato, amino, hydroxyl and choline; and in which the non-polar hydrophobic group Y is selected from saturated or unsaturated hydrophobic aliphatic hydrocarbon groups and such aliphatic hydrocarbon groups which are substituted by at least one aromatic or cycloaliphatic group and mixtures of such phospholipids and lipid-like substances, so as to form a colloidal dispersion of the first aqueous liquid in the carrier liquid, the dispersed phase globules, each being bounded by a monomolecular film of the compound of the general formula XY; combining this dispersion with a second aqueous liquid to form a heterogeneous two-layer system comprising an upper liquid layer formed by the dispersion and a lower liquid layer formed by the second aqueous liquid, the two layers being separated by the monomolecular film of the compound of formula XY; and then centrifuging the two-layer system at an angular velocity sufficient for the dispersed globules of the first aqueous liquid to be forced by gravity through the monomolecular separating film of the compound XY and into the lower layer of the second aqueous liquid.