Various embodiments of a method of preparing sustained release microparticles are described. In one embodiment, the method includes the steps of forming a dispersed phase of an active agent in a polymer and combining the dispersed phase with a continuous phase to form a microparticle dispersion. The method further includes the step of adding a measured amount of a dilution composition to the microparticle dispersion. It has been found herein that the various embodiments for preparing sustained release microparticles using various amounts of the dilution composition alters the release rate of the sustained microparticle for the specific active agent.
