Biodegradable microspheres for the intravitreal administration of acyclovir: in vitro in vivo evaluation

The purpose of this work is the preparation of microparticulate systems containing acycloguanosine, their characterization, and the description of in vitro release profiles and humoral drug concentration after intravitreal administration. Polylactides and polylactide-co-glycolide biopolymers with different molecular weights ranging between 3000 and 109 000 were employed. Microparticle preparation has been performed by spray-drying. Good results in terms of encapsulation efficiency have always been obtained. Results show that morphological characteristics of the microparticulate systems obtained and their in vitro dissolution behaviour, depend on polymer molecular weight. In vivo evaluation has been performed by intravitreal administration of microspheres in rabbits. The results show that in vivo sustained release of drug is achieved. (C) 1997 Elsevier Science B.V.