Abstract: Dispersible colloidal systems of amphiphilic lipids in the form of oligolamellar liposomes of submicron dimensions are prepared by combining a first liquid phase consisting essentially of a solution of the lipids with a greater amount of a second liquid phase consisting essentially of water. The solvent for the first liquid phase is miscible in all proportions with water. If desired, the first liquid phase may also contain a substance A in solution therewith, such as cholesterol. An additional substance B, which is a biologically active substance, may be present in the first phase if it is lipophilic, and in the second phase if it is hydrophilic.

Abstract: The Process according to the invention comprises:(1) the preparation of a liquid phase consisting essentially of a solution of the substance in a solvent or in a mixture of solvents to which may be added one or more surfactants,(2) the preparation of a second liquid phase consisting essentially of a non-solvent of a mixture of non-solvents for the substance and to which may be added one or more surfactants, the non-solvent or the mixture of non-solvents for the substance being miscible in all proportions with the solvent or the mixture of solvents for the substance,(3) the addition of one of the liquid phases prepared in (1) or (2) to the other with moderate stirring so as to produce a colloidal suspension of nanoparticles of the substance and,(4) if desired, the removal of all or part of the solvent or the mixture of solvents for the substance and of the non-solvent or the mixture of non-solvents for the substance so as to produce a colloidal suspension of nanoparticles of the desired concentration or to pro