There is an increasing need for successfully managing the rapidly progressing posterior eye diseases such as age-related macular degeneration, diabetic retinopathy and glaucoma. Therefore the challenges of drug delivery to the posterior eye are compounded by growing number of new therapeutic entities and the need for chronic therapy. Currently, the intravitreal route is widely used to deliver drugs, but frequent administration of drugs via this route can lead to retinal detachment, endophthalmitis and increased intraocular pressure. Controlled delivery systems, such as implants and nanoparticles have been developed to overcome these issues, but they are not devoid of adverse effects. Periocular route is a promising alternative owing to the large surface area and the relatively high permeability of the sclera. Yet, the blood retinal barriers and efflux transporters hamper the transport of therapeutic entities to the retina. As such the efficient delivery of drugs to the posterior eye remains a major challenge facing the pharmaceutical scientist. This review discusses the barriers to posterior eye drug delivery and current strategies used to overcome these barriers.
Keywords: Implants, Intravitreal route, Iontophoresis, Microneedles, Posterior eye drug delivery, Transscleral route, Drug Delivery Systems, transscleral routes, transdermal delivery