Coagulation Disorders Caused by Circulating Anticoagulants By Joel L Moake, MD, Baylor College of Medicine Reviewed / Revised Sep 2021 | Modified Sep 2022 View Patient Education Factor VIII and Factor IX Anticoagulants Treatment Circulating anticoagulants are usually autoantibodies that neutralize specific clotting factors in vivo (eg, an autoantibody against factor VIII or factor V) or inhibit phospholipid-bound proteins in vitro (antiphospholipid antibodies).