 Emixustat hydrochloride is a non-retinoid small molecule inhibitor of RPE65 (retinal pigment epithelium-specific 65 kDa protein, also known as retinoid isomerohydrolase).It is thought to reduce visual chromophore biosynthesis and prevent the accumulation of toxic retinal byproducts.A significant factor in the pathogenesis of age-related macular degeneration (AMD) is thought to be the toxic byproduct, N-retinylidene-N-retinylethanolamine (A2E).