Ranibizumab (RG-6321) is a humanized anti-VEGF monoclonal antibody fragment and can recognize all VEGF-A isoforms?(VEGF110, VEGF121, and VEGF165). Ranibizumab slows vision loss in vivo and is used for wet age-related macular degeneration (AMD) research.In Vitro: Ranibizumab (RG-6321) is a humanized anti-VEGF monoclonal antibody fragment (IgG antigen-binding fragment (Fab-Y0317)[2]. Ranibizumab (0.0625-0.25 mg/ml; 72 hours) results in increased necrosis and apoptosis at in rat retinal cell cultures.In Vivo: Studies in monkeys demonstrates that after a single intravitreal administration, Ranibizumab can distribute rapidly to the retina (6–24?h). Ranibizumab can rapidly penetrate through the retina to reach the choroid, just 1?h after intravitreal administration in rabbits.In a study comparing the pharmacokinetics of 0.5?mg of intravitreal Ranibizumab with 1.25?mg of intravitreal Bevacizumab in the rabbit, the vitreous half-life of Ranibizumab is 2.88 days, shorter than the Bevacizumab half-life of 4.32 days. Peak concentrations in the aqueous humor of the treated eye at 3 days following treatment are 37.7?μg/ml for Bevacizumab?and 17.9?μg/ml for Ranibizumab, respectively.