Changing practice of anticoagulation: will target-specific anticoagulants replace warfarin?

The target-specific oral anticoagulants are a class of agents that inhibit factor Xa or thrombin. They are effective and safe compared to warfarin for the prevention of stroke and systemic embolism in patients with atrial fibrillation and for the treatment of venous thromboembolism, and they are comparable to low-molecular-weight heparin for thromboprophylaxis after hip or knee arthroplasty. For other indications, however, such as the prevention of stroke in patients with mechanical heart valves, initial studies have been unfavorable for the newer agents, leaving warfarin the anticoagulant of choice. Further studies are needed before the target-specific anticoagulants can be recommended for patients with cancer-associated thrombosis or heparin-induced thrombocytopenia. Concerns also persist about difficulties with the laboratory assessment of anticoagulant effect and the lack of a specific reversal agent. For these reasons, we anticipate that the vitamin K antagonists will continue to be important anticoagulants for years to come.

Anticoagulation techniques in apheresis: from heparin to citrate and beyond.

Anticoagulation is essential for maintaining the fluidity of extravascular blood on the apheresis circuit. Although both citrate and heparin are used as an anticoagulant during apheresis, citrate is preferred for the majority of exchange procedures because of its safety and effectiveness. Complications of citrate are primarily due to physiologic effects of hypocalcemia. Symptoms of hypocalcemia and other citrate-induced metabolic abnormalities affect neuromuscular and cardiac function and range in severity from mild dysesthesias (most common) to tetany, seizures, and cardiac arrhythmias. Oral or intravenous calcium supplementation is advised for decreased ionized calcium levels and/or symptomatic management of hypocalcemia. Heparin-based anticoagulation is limited to certain apheresis procedures (membrane-based plasma exchange, LDL apheresis, or photopheresis) or is used in combination with citrate to reduce citrate load. While effective, heparin anticoagulation is associated with an increased frequency of bleeding complications and heparin-induced thrombocytopenia. J. Clin. Apheresis 2012. © 2012 Wiley Periodicals, Inc.