in accordance with the present invention , there are provided compositions and methods useful for the in vivo delivery of substantially water insoluble pharmacologically active agents in which the pharmacologically active agent is delivered in the form of suspended particles coated with protein . in particular , protein and pharmacologically active agent in a biocompatible dispersing medium are subjected to high shear , in the absence of any conventional surfactants , and also in the absence of any polymeric core material for the particles . the procedure yields particles with a diameter of less than about 1 micron . the use of specific composition and preparation conditions , and careful election of the proper organic phase and phase fraction , enables the reproducible production of unusually small nanoparticles of less than 200 nm diameter , which can be sterile - filtered . the particulate system produced according to the invention can be converted into a redispersible dry powder comprising nanoparticles of water - insoluble drug coated with a protein , and free protein to which molecules of the pharmacological agent are bound . this results in a unique delivery system , in which part of the pharmacologically active agent is readily bioavailable , and part of the agent is present within .