Ranibizumab is a recombinant humanized IgG1 kappa isotype monoclonal antibody fragment designed for intraocular use. Ranibizumab binds to and inhibits the biologic activity of human vascular endothelial growth factor A (VEGF-A). Ranibizumab has a molecular weight of approximately 48 kilodaltons and is produced by an E. coli expression system in a nutrient medium containing the antibiotic tetracycline (tetracycline is not detectable in the final product). Ranibizumab is marketed under the name Lucentis. It is indicated for the treatment of macular edema after retinal vein occlusion, age-related macular degeneration (wet), and diabetic macular edema.