One of the microsphere topics that seems to be growing these days is biodegradability.? For those of you who are unfamiliar with the topic an excellent introductory article can be found in: Advance Drug Delivery Reviews 52 (2001) 5-16, called “Biodegradable microspheres for vitreoretinal drug delivery.”? The article does a good job describing the advantages of the various polymers available, such as poly(lactic acid) [PLA], poly(glycolic acid) [PGA], and its copolymer poly(lactic-coglycolic) acid [PLGA].
The article also recommends the prefered sterlization method for drug delivery (the authors recommend irradiation).
Vitreoretinal disorders are one of the major causes of blindness in the developed world. Treatments of these pathologies often include repeated intravitreous injections to achieve intraocular drug levels within the therapeutical range. However, the risks of complications increase with the frequency of intravitreous injections. Controlled drug delivery formulations, offer an excellent alternative to multiple administrations. These systems are capable of delivering drugs over longer time periods than conventional formulations. 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 injectable microparticles, the most commonly used are poly(lactic acid), poly(glycolic acid) and copolymers of lactic and glycolic acids because they are biocompatible and degrade to metabolic products that are easily eliminated from the body. This article reviews the literature of biodegradable polymeric microspheres loaded with drugs, that have been investigated for delivery by intravitreous injection to treat diverse vitreoretinal diseases.