An antioxidant eye drop (OT-551, Othera) is being investigated to treat geographic atrophy in dry age-related macular degeneration (AMD), said Paul Sternberg, MD, from the Vanderbilt Eye Institute, Vanderbilt University School of Medicine, Nashville, TN.

The small lipophilic molecule has been shown to penetrate the cornea easily and in animal models, therapeutic levels were achieved.

"Esterases within the eye convert OT-551 to TEMPOL-H, an agent developed to treat cataracts," Dr. Sternberg said. "While TEMPOL-H does not penetrate the cornea, OT-551 does. When [either] eye drop is administered, both get into the vitreous cavity and both have activity inside the eye. The eye drop is rapidly distributed within the eye and the levels in the retina have been measured for up to 16 hours beginning within 15 minutes after topical administration."

In the Multicenter Evaluation of Geographic Atrophy phase II, 2-year study (a randomized, double-masked, dose-ranging, multicenter trial), the efficacy of the eye drop is being compared with placebo at doses of 0.45% and 0.3% to determine the effect of the eye drops in reducing the area of progression of geographic atrophy following treatment. Patients administer the drug four times daily for 2 years in one eye. Investigators will evaluate the changes in best-corrected visual acuity and safety.

The first patients were randomly selected in June 2007 and the final patients were randomly selected in March 2008. Twelve-month data are expected in spring 2009.

"Dry AMD remains a major cause of visual loss and probably will increase in its importance," Dr. Sternberg said. "As a result, there is increased interest in developing pharmacologic treatments. In studying those new agents, we believe that morphologic end points may be preferable to functional end points. [The eye drop] is one of several drugs that we think is promising, under study, and applied topically."