Emulsions for use in precipitating water-insoluble drug nanoparticles. The continuous phase of the emulsions include water and an external surfactant. The discontinuous phase of the emulsions include butyl lactate, a co-solvent, an internal surfactant and a water-insoluble drug that is solubilized in the discontinuous phase. The emulsions allow for the precipitation of nanoparticles of water-insoluble drugs that are otherwise difficult or impossible to precipitate using conventional emulsion techniques.