Ruboxistaurin is an orally bioavailable, selective, potent inhibitor of protein kinase C β developed for treating diabetic retinopathy. In vitro and in vivo non-clinical models have demonstrated that Ruboxistaurin decreases PKC β activity and ameliorates many of the effects of PKC β on pathologic processes in the retina. Ruboxistaurin prevents the slowing of retinal blood flow that is observed by fluorescein video angiography in the eyes of diabetic rats. It is also reported to cause regression of retinal neovascularization produced by laser-induced major branch vein occlusions in a porcine model. Ruboxistaurin positively affected the diabetes-induced retinal blood flow abnormalities in a Phase Ib study in diabetic patients. Ruboxistaurin is in phase III clinical trials for the treatment of diabetic nephropathy and diabetic macular edema. Eli Lilly had submitted Ruboxistaurin for approval in the US and the EU; however, the company subsequently discontinued development as it was unable to demonstrate sufficient efficacy