Biodegradable microspheres for vitreoretinal drug delivery

Vitreoretinal disorders are one of the major causes of blindness in the dev eloped world. Treatments of these pathologies often include repeated intrav itreous injections to achieve intraocular drug levels within the therapeuti cal range. However, the risks of complications increase with the frequency of intravitreous injections. Controlled drug delivery formulations, offer a n excellent alternative td multiple administrations. These systems are capa ble of delivering drugs over longer time periods than conventional formulat ions. Currently, several kinds of polymer devices for drug delivery to the posterior segment of the eye are under clinical use, or under investigation . Among these devices, microparticulates, such as microspheres, provide an alternative to multiple injections to obtain sustained release of the drug with a single administration. Among the polymers used to make the injectabl e microparticles, the most commonly used are poly(lactic acid), poly(glycol ic acid) and copolymers of lactic and glycolic acids because they are bioco mpatible and degrade to metabolic products that are easily eliminated from the body. This article reviews the literature of biodegradable polymeric mi crospheres loaded with drugs, that have been investigated for delivery by i ntravitreous injection to treat diverse vitreoretinal diseases. (C) 2001 El sevier Science B.V All rights resented.