Process for the preparation of dispersible colloidal systems of a substance in the form of nanoparticles

A process for the preparation of dispersible colloidal systems of a substance in the form of spherical particles of the matrix type and of a size less than 500 nm (nanoparticles), comprising:

• combining (1) a first liquid phase consisting essentially of a solution of a film-forming material and a biologically active substance in a solvent or in a mixture of solvents to which may be added one or more surfactants, and (2) a greater volume of a second liquid phase consisting essentially of a non-solvent or a mixture of non-solvents for the film-forming material and biologically active substance and to which may be added one or more surfactants, the non-solvent or the mixture of non-solvents for the film-forming material and biologically active substance being miscible in all proportions with the solvent or mixture of solvents for the film-forming material and biologically active substance;
• thereby substantially instantaneously to precipitate from said solvent and said non-solvent composite particles of said film-forming material and biologically active substance to produce a colloidal suspension of composite nanoparticles.