The invention relates to a multistage process in order to produce, in a very effective and careful manner, particles having an average particle size of 50 nm to 1000 nm, during which the solid substance (active substance) is dissolved in a solvent, and this liquid containing the solid substance (active substance) in dissolved form is then rapidly frozen. The solvent(s) used are removed from the obtained frozen matrix optionally during a (freeze)-drying process (lyophilization) or the frozen matrix is subjected to a direct subsequent processing. The solid matrix is dispersed in an outer phase and the resulting dispersion is then immediately subjected to high shear and/or cavitation forces. The forces used lead to a stabilization or reduction in size of the resulting particles on the nanometric scale.

The invention describes a multistage process, for producing particles with an average particle size from 50 nm to 1000 nm in a very effective and gentle manner, wherein the solid substance (active substance) is dissolved in a solvent, this liquid containing the solid substance (active substance) in dissolved form is then frozen very rapidly, the solvent/solvents used are optionally removed from the frozen matrix obtained in a (freeze-)drying process (lyophilisation) or the frozen matrix is further processed directly, the solid matrix (frozen or lyophilised) is dispersed in an external phase, a liquid medium, which can be water, a mixture of water with water-miscible liquids or a non-aqueous liquid, and the resulting dispersion is then immediately exposed to high shear and/or cavitation forces, and the forces applied result in stabilisation or comminution of the resulting particles in the nanometre range. The method described is particularly suitable for the processing of thermolabile and sensitive substances, since it can be performed in a manner very gentle to the product, and the wear on the devices used can be markedly decreased by reduction of the necessary cycle number or by reduction of the power density to be applied. The nanoparticles obtained can be used in various fields, e.g. in the pharmaceutical field, in the cosmetic industry, the foodstuffs industry, the textile industry and other industrial fields.