Drug delivery methods for posterior segment disease

New pharmacotherapies for posterior segment diseases of the eye have been recently introduced which use novel drug delivery methods. The various current and potential future methods will be discussed.

Drug delivery systems have been developed which can provide controlled release of drug for potentially long periods of time. Ideal candidates for these devices are chronic conditions that require repeated local administration of drug, such as noninfectious intermediate or posterior uveitis, neovascular age-related macular degeneration, and persistent macular edema due to diabetic retinopathy or venous occlusive disease. Recently, Retisert (Bausch & Lomb, Rochester, New York, USA), a nonbiodegradable fluocinolone acetonide implant, was approved for use in noninfectious uveitis affecting the posterior segment and is currently in clinical trials for the treatment of macular edema. A biodegradable dexamethasone implant is currently in clinical trials for the treatment of uveitis and diabetic macular edema.

With the development of therapeutic agents that require repeated administration comes a need for new strategies to improve safety and maximize efficacy. Novel drug delivery systems involving nonbiodegradable or biodegradable implants, microparticulates or nanoparticulates, liposomes, or transscleral iontophoresis may provide the solution.