A process for making particles for delivery of drug nanoparticles is disclosed herein. The process comprises the steps of (a) forming a suspension of drug nanoparticles by mixing a precipitant solution with an anti-solvent solution under micro-mixing environment, where the formed nanoparticles have a narrow particle size distribution； (b) providing an excipient to at least one of the precipitant solution, the anti-solvent solution and the suspension of drug nanoparticles, the excipient being selected to maintain said drug nanoparticles in a dispersed state when in liquid form； and (c) drying the suspension of drug nanoparticles containing the excipient therein to remove solvent therefrom, wherein removal of the solvent causes the excipient to solidify and thereby form micro-sized matrix particles, each micro-sized particle being comprised of drug nanoparticles dispersed in a solid matrix of the excipient.
