A method and an apparatus is provided for forming fine particles of a substance, comprising: (a) mixing a first nongaseous supercritical fluid, a solution or suspension of said substance in a second nongaseous fluid, and a third nongaseous fluid to form a composition; and (b) reducing the pressure on said composition whereby a dispersion of said fine particles of said substance is formed; wherein the first and second nongaseous fluids are immiscible and wherein the substance comprises a physiologically active composition.