New prodrugs of therapeutically active compounds, including oligomeric prodrugs of ethacrynic acid, and compositions to treat medical disorders, for example glaucoma, a disorder or abnormality related to an increase in intraocular pressure (IOP), a disorder requiring neuroprotection, age-related macular degeneration, or diabetic retinopathy. Also a method for the controlled administration of timolol to a patient in need thereof, such as a human, comprising administering a prodrug of timolol in a microparticle in vivo, wherein the timolol prodrug containing microparticle exhibits in vitro drug release kinetics in an aqueous solution at a pH between 6-8 at body temperature of a substantially consistent release of at least 60% timolol itself by molar ratio to the prodrug of timolol or an intermediate metabolite thereof over at least 100 days.
