Trojan Microparticles Potential for Ophthalmic Drug Delivery

The administration of drugs to treat ocular disorders still remains a technological challenge in this XXI century. Although there is an important arsenal of active molecules useful to treat ocular diseases, ranging from classical compounds to biotechnological products, currenty, no ideal delivery system is able to profit all their therapeutic potential. Among the Intraocular Drug Delivery Systems (IODDS) proposed to overcome some of the most important limitations, microsystems and nanosystems have raised high attention. While microsystems are able to offer long-term release after intravitreal injection, nanosystems can protect the active compound from external environment (reducing their clearance) and direct it to its target tissues. In recent years, some researchers have explored the possibility of combining micro and nanosystems in “Nanoparticle-in-Microparticle (NiMs)” systems or “trojan systems”. This excellent idea is not exempt of technological problems, remains partially unsolved, especially in the case of IODDS. The objective of the present review is to show the state of art concerning the design, preparation and characterization of trojan microparticles for drug delivery and to remark their potential and limitations as IODDS, one of the most important challenges faced by pharmaceutical technology at the moment.