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Novel delivery systems of active substances for intraocular administration

Neurodegenerative pathologies affecting the posterior segment of the eye such as diabetic retinopathy, age related macular degeneration and glaucoma are among the main causes of blindness in the world. They have in common that are cronic, multifactorial and in some cases related with the elderly. The treatment of these pathologies require to maintain therapeutic concentrations in the posterior segment thanks to the use of successive intraocular injections which are associated to secondary effects being poor tolerated by patients.
Intraocular drug delivery systems emerged as an alternative to frequent injections as they are able to deliver the therapeutic agent in a controlled fashion into the eye after a single administration. Depending on the biomaterial these delivery systems are biodegradable or non biodegradable. Attending to their sizes, drug delivery systems are classified in implants (>1mm), microsystems (1-1000μm) y nanosystems (1-1000nm).
Biodegradable microspheres emerge as therapeutic tools of great interest for the treatment of neurodegenerative pathologies as they can encapsulate active substances of distinct nature and provide release profiles tailoring with clinical needs. Furthermore, it is possible to administer different amounts of microspheres which correspond to the most adequated doses of the medicine in a personalized therapy. The simultaneous encapsulation of several active substances in the microspheres are of great interest in the treatment of multifactorial diseases covering different therapeutic targets.