Drug delivery systems intravitreal administration

Various colloidal systems have been studied for use as potential ophthalmic delivery systems, including liposomes and nanoparticles. Liposomes are bioerodible and biocompatible systems consisting of microscopic vesicles composed of lipid bilayers surrounding aqueous compartments. Liposomes have demonstrated prolonged drug effect at the site of action but with reduced toxicity. Ophthalmic studies have included topical, subconjunctival, and intravitreal administration, but no commercial preparations are currently available for ophthalmic use. 

Sustained delivery of ophthalmic medications is a novel approach in treating chronic intraocular infections in conditions where systemic administration is accompanied by undesirable side-effects and repeated intravitreal injections carry the risk of infection. The administration of medications by implants or depot devices is a very rapidly developing technology in ocular therapeutics. The various types of implant and mechanisms of drug release have been discussed in general in Chapter 4. 

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