Abstract
Ruboxistaurin (Eli Lilly, Indianapolis, IN), an orally active inhibitor of the β isoform of protein kinase C (PKC), has been studied as a systemic treatment for diabetic retinopathy. PKC-β appears to be overactivated in response to hyperglycemia. This overactivation associates with various pathological effects within the retinal vascular system, including ischemia, vascular leakage, and angiogenesis. Several randomized clinical trials of ruboxistaurin have been performed. In most trials, the primary outcomes were not achieved. Analysis of secondary outcomes data from these trials has demonstrated some evidence of safety and efficacy in the treatment of diabetic retinopathy. At this time, ruboxistaurin has not received approval from the US Food and Drug Administration.