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.