Name: Antithrombin III (Human)

Thrombate III - Bayer Corp., Elkhart, IN

Description/Contents: Antithrombin III (AT III) is a sterile lyophilized preparation of human antithrombin isolated from pooled plasma by a modification of the Cohn fractionation technique. Viral attenuation is achieved by heat treatment at 60oC for at least 10 hours. It has not been shown to transmit viral infections. AT III is thought to serve as a control mechanism on low-level coagulation activation in the circulation: it inhibits thrombin, Factor Xa and other serine proteases much more efficiently in plasma than when those factors are bound to platelets or fibrin. Heparin markedly potentiates the inhibitory activity of AT III.

• AT III is FDA approved for use in the treatment of patients with hereditary AT III deficiency as prophylaxis against thrombosis following surgery or obstetric procedures and for therapeutic use when such patients have thrombosis. Without adequate levels of AT III, heparin is much less effective.

• Debate continues about the use of AT III concentrates in patients with “acquired” AT III deficiency, such as in cases of sepsis and DIC, or those with relative heparin resistance during surgery and extracorporeal circulation. It is not approved for pediatric use.

Dosage and Administration: Replacement therapy is designed to achieve levels of 120% following infusion, with subsequent doses (60% of the loading dose) administered empirically to keep levels between 70 to 120%. In stable, AT III deficient patients, the normal half-life of infused AT III is between 60 and 90 hours after an initial half-disappearance time of 22 hours. In acute DIC, the half-life is usually half that of stable patients, and may be a short as 4 hours.

Dosage should be determined on an individual basis based on the pre-therapy plasma antithrombin III level, in order to increase the plasma AT III level to that normally found in human plasma (100%). Incremental in vivo recovery of 1.4% per IU/kg administered is expected. Hematologic consultation is recommended.

Alternative Therapy: None available.

Bucur SC, Levy JH, Despotis GJ et al. Uses of antithrombin III concentrates in congenital and acquired deficiency states. Transfusion 38: 481, 1998.

Menache D, Grossman BJ, Jackson CM. Antithrombin III: physiology, deficiency and replacement therapy. Transfusion 32:580, 1992.

Transfusion Guidelines

Plasma Guidelines	Antithrombin III Guidelines
Platelet Guidelines	Activated Protein Guidelines
Red Cell Guidelines	Factor IX Guidelines
Cryoprecipitate Guidelines	Factor VIII Guidelines
AICC/Porcine Factor VIII Guidelines	IVIG Guidelines Coagulation Factor VII Guidelines

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