Pexelizumab is a humanized single chain monoclonal antibody that targets complement component 5 (C5) thus blocking the conversion of C5 to C5a and C5b-9. Pexelizumab inhibits complement-mediated tissue damage associated with reperfusion injury and inflammation that occurs during open heart surgery. Pexelizumab has the potential for the treatment of coronary artery bypass graft surgery and acute myocardial infarction.