Antithrombin III
Class: Anticoagulants, Miscellaneous
VA Class: BL500
CAS Number: 52014-67-2
Brands: Thrombate III
Introduction
Anticoagulant; naturally occurring plasma thrombin inhibitor.
Uses for Antithrombin III
Congenital Antithrombin III Deficiency
Short-term replacement therapy for prevention or treatment of thromboembolism in selected patients with congenital antithrombin III deficiency at high risk for thromboembolism (i.e., those undergoing surgical or obstetrical procedures) or those with thromboembolism. Has been designated an orphan drug by FDA for this use.
Confirm congenital antithrombin III deficiency based on clear family history of venous thrombosis and decreased endogenous plasma antithrombin III concentrations; exclude acquired antithrombin III deficiency.
Thromboprophylaxis (e.g., with unfractionated heparin, low molecular weight heparin) throughout pregnancy recommended by the American College of Chest Physicians (ACCP) and other clinicians in women with congenital antithrombin III deficiency. ACCP and other clinicians recommend discontinuance of heparin or low molecular weight heparin thromboprophylaxis prior to labor followed by postpartum anticoagulation with warfarin. Follow-up replacement therapy with antithrombin III in women with congenital deficiency suggested by some clinicians, initiated prior to or on day of delivery and continued postpartum. Has been used in combination with unfractionated heparin after delivery in such patients.
Management of venous thromboembolism in patients with congenital antithrombin III deficiency generally similar to that in other patients (i.e., conventional anticoagulation with unfractionated heparin, low molecular weight heparin, or fondaparinux followed by warfarin). Short-term therapy with antithrombin III suggested by some clinicians when unacceptable risks of bleeding exist with conventional anticoagulation.
Role of antithrombin III as adjunctive therapy to unfractionated heparin in patients with congenital antithrombin III deficiency and thromboembolism not clearly defined. (See Interactions.) Used to overcome unfractionated heparin resistance (e.g., IV heparin dosage >35,000–40,000 units daily required to achieve aPTT ≥1.5 times control value) in such patients. Use of antithrombin III also suggested by some clinicians in patients with severe thrombosis or breakthrough thrombosis despite anticoagulation.
Has been used in a limited number of neonates† with congenital antithrombin III deficiency. (See Pediatric Use under Cautions.)
Antithrombin III Dosage and Administration
General
Monitor antithrombin III concentrations periodically to individualize dosage and assess response to therapy. (See Laboratory Monitoring under Cautions.)
Suggested dosage recommendations are general guidelines.
Individualize dosage and duration of therapy based on clinical situation (e.g., indication for treatment, patient’s clinical condition and past history, type and extent of surgery or...
