Enfiera 500 Injection Enfiera 500 is an intravenous medicine containing rituximab, a laboratory-produced monoclonal antibody. It targets the CD20 protein found on B lymphocytes (B cells) and helps the immune system remove these cells. This makes it useful in several B-cell cancers and certain autoimmune disorders where abnormal B-cell activity plays a role. The medicine is supplied as a 50 mL single-use vial and must be diluted before intravenous administration.