Composition composed of an aqueous dispersion of stabilized vesicles of nonionic amphiphilic lipids

Claim 1

A process for imparting hydrolysis stability to vesicles dispersed in an aqueous phase, said vesicles comprising a membrane of a lipid phase encapsulating an aqueous phase, said vesicles being prepared from a lipid phase, said process comprising combining a nonionic amphiphilic lipid mixture with at least one ionic amphiphilic lipid in an amount sufficient to impart to said aqueous phase a pH ranging from 5.5 to 7.5 said nonionic amphiphilic lipid mixture being a mixture of esters of at least one polyol and a fatty acid, said at least one polyol being selected from the group consisting of polyethylene glycol containing 1 to 60 ethylene oxide units, sorbitan, sorbitan containing 2 to 60 ethylene oxide units, glycerol containing 2 to 30 ethylene oxide units, a polyglycerol containing 2 to 15 glycerol units, sucrose, and glucose containing 2 to 30 ethylene oxide units, and said fatty acid being a fatty acid containing a saturated or unsaturated, linear or branched C 5 -C 17 alkyl chain, the number of alkyl chains per polyol group ranging from 1 to 10; and said ionic amphiphilic lipid being selected from the group consisting of an alkali metal salt of dicetyl phosphate, an alkali metal salt of dimyristyl phosphate, and alkali metal salt of cholesterol sulphate, an alkali metal salt of cholesterol phosphate, monosodium acyl glutamate, disodium acyglutamate, a phospholipid and an alkyl sulphonic compound having the formula: ##STR7## wherein R represents C 16 H 33 or C 18 H 37 and M represents an alkali metal, or a mixture thereof; the weight ratio of said nonionic amphiphilic lipid to said ionic amphiphilic lipid in said lipid phase being between 50:1 and 50:25.