Sustained-Release Drug Delivery in Uveitis

Intraocular Sustained-Release Drug Delivery in Uveitis 

Duke University Eye Center, Durham, North Carolina, U.S.A. 

Uveitis treatments can be delivered topically, periocularly, intraocularly or systemically, and there are problems common to all delivery techniques and specific to each delivery method. Compliance with any form of regular medication can be a problem particularly if its administration is associated with discomfort or if its side effects are unpleasant. Some medications, particularly hydrophobic compounds, may cross the blood-retinal barrier poorly, which is an important consideration for all delivery systems except intraocular injections. Topical medications, which have the least side effects, do not penetrate into the posterior segment and are unsuitable for posterior uveitis, which is often sight-threatening. 

Intraocular injections are associated with significant complications and often must be repeated at regular intervals in patients with a chronic disease such as uveitis. Similar difficulties are associated with periocular injections although the complication rate is lower and those that do occur are usually less severe. The main 

Sustained intraocular corticosteroid delivery can overcome systemic side effects associated with oral topical and periocular therapy while at the same time provide effective suppression of intraocular inflammation (5-9). However, sustained intraocular therapeutic corticosteroid levels are required to adequately treat uveitis that typically has a chronic and recurrent course. Some corticosteroids such as dexa-methasone phosphate are less suitable for treatment of chronic intraocular inflammation as they have half-lives of 4 hours when administered intravitreally and are rapidly removed from the eye (5,9). 

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