Abstract: This invention is directed to an apparatus and method for producing microparticles comprising pharmacologically active agents and biodegradable polymers. The apparatus includes a spinning disk containing a reservoir in the center thereof and a flat inclined surface. The apparatus optionally includes serrations and/or a flat surface beneath the periphery of the disk that is parallel to the rotational axis of the disk. The invention is also directed to a method for producing microparticles containing pharmacologically active agents, using the spinning disk apparatus. Formulations containing ophthalmically active agents are provided. Formulations exhibiting zero order release rates are also described.