Recent patents on ocular drug delivery systems.

There are three main routes for delivery of drugs to the eye: topical, systemic and intra-ocular injection. Controlled delivery systems, such as ocular inserts, minitablets and disposable lenses, can be applied to the exterior surface of the eye for treatment of conditions affecting the anterior segment of the eye. Extended residence times following topical application have the potential to improve bioavailability of the administered drug and additionally a range of strategies has been tested to improve penetration including cyclodextrins, liposomes and nanoparticles. The first part of this review will focus on recent patent filings in this area. The second part of the review reports on drug delivery strategies for treatment of diseases of the posterior segment of the eye. The development of therapeutic agents that require repeated, long-term administration is a driver for the development of sustained-release drug delivery systems to result in less frequent dosing and less invasive techniques. This review article focuses on recently patented applications (from March 2004 to present) of drug delivery systems for ocular delivery.