Liposome-forming composition

Claim 2

A pro-liposome composition comprising a uniform mixture of:- a) at least one membrane lipid, b) at least one water-miscible organic solvent selected from ethanol, isopropyl alcohol, methanol and butanol, and optionally c) an amount of water, such that, on addition of excess water, the composition spontaneously forms vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 3

A pro-liposome composition comprising a uniform mixture of:- a) at least one membrane lipid, b) at least one water-miscible organic solvent, and c) water in an amount less than that which results in formation of liposomes, such that, on addition of excess water, the composition reorganises into vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 4

A pro-liposome composition comprising a uniform mixture of:- a) at least one membrane lipid, b) at least one water-miscible organic solvent, and c) water in an amount less than that which results in formation of liposomes, such that, on addition of excess water, the composition reorganises into vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 5

A composition according to claim 1 or 2, containing a small amount of water resulting in the formation of a network or stack of expanded bilayers, the composition reorganising into liposomes on addition of excess water.

Claim 6

A composition according to claim 1, containing water resulting in the formation of bilayers with water inclusions entrapped within said bilayers, the composition reorganising into liposomes on addition of excess water.

Claim 7

A pro-liposome composition comprising a uniform mixture of:- a) at least one membrane lipid and b) at least one water-miscible organic solvent selected from ethanol, isopropyl alcohol, methanol and butanol, the proportion by weight of a) to b) being from 40:1 to 1:20, which upon the addition of a small amount of water forms a network or stack of expanded bilayers, addition of further water leading to the entrapment of water inclusions within the said bilayers and addition of excess water and optionally agitation leading to the breakdown of this structure to form vesicles or liposomes.

Claim 8

A pro-liposome composition comprising a uniform mixture of:- a) at least one membrane lipid and b) at least one water-miscible organic solvent selected from ethanol, isopropyl alcohol, methanol and butanol, the proportion by weight of a) to b) being from 40:1 to 1:20, which upon the addition of a small amount of water forms a network or stack of expanded bilayers, addition of further water leading to the entrapment of water inclusions within the said bilayers and addition of excess water and optionally agitation leading to the breakdown of this structure to form vesicles or liposomes.

Claim 9

A pro-liposome composition in anhydrous form comprising a uniform mixture of:- a) at least one membrane lipid, and b) a mixture of at least one water-miscible organic solvent selected from ethanol, isopropyl alcohol, methanol and butanol, with at least one other water-miscible organic solvent, such that, on addition of excess water, the composition spontaneously forms vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 10

A pro-liposome composition in anhydrous form comprising a uniform mixture of:- a) at least one membrane lipid, and b) a mixture of at least one water-miscible organic solvent selected from ethanol, isopropyl alcohol, methanol and butanol, with at least one other water-miscible organic solvent, such that, on addition of excess water, the composition spontaneously forms vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 11

An aerosol composition comprising in a volatile liquid propellant:- a) at least one membrane lipid, b) at least one water-miscible organic solvent, and optionally c) up to 40%, by weight on the combined weights of a), b) and c), of water, such that, on coming into contact with excess water, the composition spontaneously forms vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 12

An aerosol composition comprising in a volatile liquid propellant:- a) at least one membrane lipid, b) at least one water-miscible organic solvent, and optionally c) up to 40%, by weight on the combined weights of a), b) and c), of water, such that, on coming into contact with excess water, the composition spontaneously forms vesicles or liposomes, the proportion by weight of a) to b) being from 40:1 to 1:20.

Claim 13

A pro-liposome composition as claimed in any of claims 1 to 4, wherein from 5% to 40% by weight of water is present as component c).

Claim 14

A composition as claimed in any one of claims 1 to 8, wherein there is also present up to 25% of a fatty acid ester.

Claim 15

A composition as claimed in any one of claims 1 to 9, wherein the volatile water-miscible organic solvent is ethanol.

Claim 16

A composition as claimed in any one of claims 1 to 10, wherein cholesterol is also present together with one or both of stearylamine and cetyl phosphate.

Claim 17

A composition as claimed in any one of claims 1 to 11, wherein there is also present a biologically active compound.

Claim 18

A pro-liposome composition as claimed in claim 1 or claim 2, wherein the proportion of component a) is from 35% to 55% by weight, the proportion of component b) is from 30% to 55% by weight and the proportion of water as component c) is from 5% to 20% by weight.

Claim 19

An aerosol composition as claimed in any one of claims 7 and claims 9 to 12 when dependent thereon, wherein the proportion by weight of component a) to component b) is from 1:2 to 1:10.

Claim 21

A method as claimed in claim 15, wherein the excess water is added at elevated temperature and the liposomes are formed upon subsequent cooling to ambient temperature.

Claim 22

A method as claimed in claim 15 or 16, wherein the water is mixed in two stages.

Claim 23

A method as claimed in claim 15, 16 or 17, wherein the water contains a biologically active compound that becomes entrapped in the membrane lipid, the biologically active compound optionally comprising a medicament, protein, enzyme, hormone, vitamin or marker compound.

Claim 24

A method as claimed in claim 15 and claims 17 and 18 when dependent thereon, wherein the mixing step is performed in vitro.

Claim 26

A method as claimed in claim 15, wherein the mixing step is performed in vivo.

Claim 27

A method of making an aqueous dispersion of liposomes which comprises spraying an aerosol composition as claimed in claim 7, or any one of claims 9 to 12 and 14 when dependent thereon, so that it comes into contact with excess water.

Claim 30

A composition as claimed in any one of claims 1 to 14, in the form of an aerosol of droplets having a weight average diameter below 8 /1.m (microns).