title: Drug delivery to the posterior segment of the eye.
abstract: Delivery of drugs to the posterior eye is challenging, owing to anatomical and physiological constrains of the eye. There is an increasing need for managing rapidly progressing posterior eye diseases, such as age-related macular degeneration, diabetic retinopathy and retinitis pigmentosa. Drug delivery to the posterior segment of the eye is therefore compounded by the increasing number of new therapeutic entities (e.g. oligonucleotides, aptamers and antibodies) and the need for chronic therapy. Currently, the intravitreal route is widely used to deliver therapeutic entities to the retina. However, frequent administration of drugs via this route can lead to retinal detachment, endophthalmitis and increased intraocular pressure. Various controlled delivery systems, such as biodegradable and non-biodegradable implants, liposomes and nanoparticles, have been developed to overcome such adverse effects, with some success. The periocular route is a promising alternative, owing to the large surface area and the relatively high permeability of the sclera. Yet, the blood-retinal barrier 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. In this review, we discuss the barriers of the posterior eye drug delivery and the various drug-delivery strategies used to overcome these barriers.
authors.affiliation: Drug Delivery Research Unit (DDRU), School of Pharmacy, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1010, New Zealand. t.thrimawithana@auckland.ac.nz
authors.forename: Thilini Rasika
authors.initials: TR
authors.lastname: Thrimawithana
authors.forename: Simon
authors.initials: S
authors.lastname: Young
authors.forename: Craig Robert
authors.initials: CR
authors.lastname: Bunt
authors.forename: Colin
authors.initials: C
authors.lastname: Green
authors.forename: Raid Ghassan
authors.initials: RG
authors.lastname: Alany
mesh_terms: D000818:Animals; D001692:Biological Transport; D001813:Blood-Retinal Barrier / Q000378:metabolism; D016503:Drug Delivery Systems; D064420:Drug-Related Side Effects and Adverse Reactions; D005123:Eye / Q000378:metabolism / Q000503:physiopathology; D005128:Eye Diseases / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000378:metabolism; D012590:Sclera / Q000378:metabolism
chemical_list: D004364:Pharmaceutical Preparations