Drug delivery strategies for combination ophthalmic treatments

The most significant obstacle to the combination of drug therapies in age-related macular degeneration (AMD) may be drug delivery. Although the posterior of the eye can be reached by intravitreal injections and implants, AMD is a chronic disease process that is likely to require prolonged or indefinite exposure to antiproliferative agents. In addition to the difficulty of repeat dosing in the vitreal space, ocular anatomy prohibits substantial drug volumes, a limitation further compounded when combining two or more agents. With low penetration to target areas of AMD, pathophysiology, and risk of significant systemic toxicity through systemic drug delivery, innovative strategies for introducing agents to their site of action may be the critical component of improved outcomes.