Antithrombin alfa

Name: Antithrombin alfa



Hypersensitivity to goat protein or goat milk components


May increase risk of bleeding

Not for treatment of thromboembolic activity in hereditary antithrombin deficient patients

Monitor patients for possible immunological reactions, including antibody status

Provide appropriate clinical testing when antithrombin is used with heparin or other anticoagulants

Half-life and clearance differs significantly (7-9 times) between plasma derived and recombinant derived product

Perform anticoagulation studies (APTT, anti-Factor Xa) at close intervals when starting antithrombin treatment

Measure antithrombin levels daily, in order to adjust individual dose

Risk of diminishing antithrombin levels with prolonged treatment with non-fractionated heparin


Mechanism of Action

Serine protease inhibitor; important natural inhibitor of blood coagulation; inactivation of thrombin, plasmin, and other active serine proteases of coagulation including factors IXa, Xa, XIa, and XIIa.


Half-life: 12-18 hr; childbirth hemorrhage, surgery, and/or concomitant heparin may shorten half-life

Vd: 14.3 L (pregnant women); 7.7L (nonpregnant patients)


Biosynthetic (recombinant DNA origin) preparation of human antithrombin III, a naturally occurring anticoagulant.1 3 4 5 9

Uses for Antithrombin alfa

Congenital Antithrombin III Deficiency

Prevention of perioperative and peripartum thromboembolism in patients with congenital antithrombin III deficiency; designated an orphan drug by FDA for use in these conditions.1 2 5

Short-term thromboprophylaxis with an appropriate anticoagulant recommended in patients with congenital antithrombin III deficiency during high-risk situations (e.g., surgery, pregnancy, postpartum period);4 7 8 11 13 antithrombin III concentrates may be used when anticoagulant therapy is neither feasible (e.g., due to a bleeding risk) nor sufficient.1 3 4 5 7 11 12

Not indicated for treatment of thromboembolic events.1

Heparin Resistance

Has been used for management of heparin resistance during cardiopulmonary bypass (CPB)†.14 15 16

May reduce requirements for fresh frozen plasma and additional heparin during CPB.15 16

Interactions for Antithrombin alfa

Specific Drugs




Anticoagulants (e.g., unfractionated heparin, low molecular weight heparin, other drugs that use antithrombin III to exert their anticoagulant effects)

Possible increased anticoagulant effect1

Half-life of antithrombin alfa may be altered due to change in antithrombin turnover1

Closely monitor patients1 (see Concomitant Anticoagulant Therapy under Cautions)


  • Biosynthetic (recombinant DNA origin) preparation of human antithrombin III produced in milk of transgenic goats.1 3 4 5 9 Involves insertion of DNA coding sequence for human antithrombin III into specific promotor gene that directs expression in goat mammary glands.1 3 4 9 Isolated and purified using a series of filtration and chromatography steps; includes additional viral inactivation procedures.1 3 4 6

  • Regulates several key serine proteases in the blood coagulation pathway.1 3 4 7 9 11 Principally inhibits thrombin and factor Xa, and to a lesser extent, factors IXa, XIa, XIIa, trypsin, plasmin, tissue plasminogen activator (tPA), urokinase (no longer commercially available in the US), and kallikrein.1 3 4 7 9 11 Activity enhanced by more than 300- to 1000-fold when antithrombin III is bound to heparin.1 3 4 7 9 10 11

  • Functionally and structurally similar to endogenous antithrombin III.1 3 4 5 9

  • Also exhibits anti-inflammatory and antiproliferative effects in endothelium.4 11

For Healthcare Professionals

Applies to antithrombin (recombinant): intravenous powder for injection


Cardiovascular side effects have included hemorrhage and hematoma.[Ref]


General side effects have included hot feelings and noncardiac chest pain.[Ref]


Gastrointestinal side effects have included intraabdominal hemorrhage.[Ref]


Genitourinary side effects have included hematuria.[Ref]


Hepatic side effects have included hepatic enzyme abnormalities.[Ref]


Local side effects have included infusion site reaction and application site pruritus.[Ref]


Musculoskeletal side effects have included hemarthrosis.[Ref]

Some side effects of antithrombin (recombinant) may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Antithrombin (recombinant) Pregnancy Warnings

Antithrombin recombinant has been assigned to pregnancy category C by the FDA. Animal studies have failed to reveal evidence of embryofetotoxicity. There are no controlled data in human pregnancy. Antithrombin recombinant is only recommended for use during pregnancy when benefit outweighs risk.