Abstract: The invention provides a formulation and method for the treatment of urinary system disorders, wherein the formulation comprises a controlled release drug delivery system for intravesicular administration to a patient. Controlled release microparticles in the formulation are comprised of a pharmacologically active agent and a controlled release carrier, where the microparticles are buoyant in urine. Microparticle buoyancy in urine ensures that the formulation continues to release the active agent into a patient's bladder throughout the duration of an extended drug delivery time period. Methods of treating urinary system disorders by intravesicular administration of the microparticle formulation to a subject are also provided, and include methods of treating urinary system infections, bladder cancer, incontinence, and other urinary system disorders.