Synagis 50 mg Injection Synagis contains Palivizumab, a humanized IgG1 monoclonal antibody directed against an epitope in the A antigenic site of the fusion (F) protein of Respiratory Syncytial Virus (RSV). By binding to the F protein, palivizumab inhibits viral attachment and membrane fusion with host cell membranes, thereby neutralizing the virus and suppressing cell-to-cell fusion. It is indicated for the prevention of serious lower respiratory tract disease caused by RSV in high-risk pediatric patients, including infants born prematurely or those with bronchopulmonary dysplasia (BPD) or hemodynamically significant congenital heart disease (CHD).