A pharmaceutical composition is provided comprising microparticles encapsulating high weight percent active agent and providing sustained release over a prolonged period of time of active agent levels bioequivalent to direct administration of active agent. Polymeric microparticle compositions containing one or more active agents, and methods of making and using thereof, are described. The microparticles are optimized for the agent to be delivered, so that the hydrophobicity or hydrophilicity of the polymer and charge of the polymer maximizes loading of the agent, and the selection and molecular weight of the polymers maximize release of an effective amount of the active agent for the desired period of time.
