Antithrombin III human
Also known as: Antithrombin III, Antithrombin-III, AT-III, ATIII, ATryn, Human antithrombin, SERPINC1 protein, Thrombate III
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Summary
Human antithrombin III (AT‑III) is a plasma‑derived serine protease inhibitor used as a prescription product to replace deficient AT‑III levels. It is administered intravenously or subcutaneously to patients with hereditary AT‑III deficiency or to reduce thrombotic risk during high‑risk situations such as surgery, childbirth, or severe trauma. The preparation is a purified protein derived from donor plasma and is listed among the most costly blood‑product drugs in intensive‑care settings.
Mechanism of Action
AT‑III belongs to the serpin (serine protease inhibitor) family. It binds and inactivates key serine proteases of the coagulation cascade, principally thrombin (factor IIa) and factor Xa, thereby limiting fibrin formation. By neutralising these enzymes, AT‑III reduces the propagation of clotting and helps maintain normal anticoagulant balance in the circulation.
What the Research Shows
Three peer‑reviewed sources provide the current evidence base. A 1995 cost‑analysis of two surgical intensive‑care units identified AT‑III as one of the ten leading drug‑related expenditures, reflecting frequent use in severe trauma and acute bleeding. A 1991 report described the purification process for plasma‑derived AT‑III, confirming its availability as a high‑purity concentrate. The most substantive clinical data come from a 1990 cooperative study involving 18 patients with hereditary AT‑III deficiency. Infusions raised plasma AT‑III levels by 1.5–2.7% per unit per kilogram, with a half‑life of 43–77 hours. In 13 patients the product prevented new thrombotic events after surgery or parturition and halted progression of acute thrombosis, with no adverse events reported.
Reported Benefits
Clinical observations indicate that AT‑III replacement can reliably raise plasma AT‑III concentrations, sustain activity for several days, and effectively prevent or halt thrombosis in patients with hereditary deficiency undergoing high‑risk procedures. The 1990 study reported no side‑effects, no hepatitis B seroconversion, and stable liver enzymes when AT‑III was used without concurrent blood‑product transfusions.
Limitations of the Evidence
Evidence is limited to a single, non‑randomised cohort of 18 patients, all with hereditary AT‑III deficiency; data for acquired deficiency or broader thrombotic indications are absent. The studies do not compare AT‑III with alternative anticoagulants, and cost analyses highlight its high expense without demonstrating cost‑effectiveness. Long‑term safety and efficacy beyond the acute setting remain uncharacterised.
Safety Considerations
In the reported cohort, AT‑III was well tolerated with no immediate adverse reactions. Follow‑up showed no hepatitis B seroconversion and no elevations in alanine aminotransferase among patients who did not receive other blood products. However, safety conclusions are drawn from a small sample, and rare immunologic or infectious risks associated with plasma‑derived products cannot be excluded.
How It Is Administered
Human AT‑III is supplied as a sterile concentrate for intravenous or subcutaneous injection. The formulation is derived from pooled human plasma and is stored refrigerated until use. Dosing regimens are individualized based on body weight and target plasma AT‑III activity, but specific protocols are not detailed in the available literature.
Routes of Administration
Goals & Uses
- Treatment of acute thrombotic eventsTreatmentModerate
- DIC (disseminated intravascular coagulation) managementOff Label / InvestigationalLow
- Perioperative thromboprophylaxis in AT-III-deficient patientsSurgical Risk ManagementHigh
- Prevention of thromboembolic events in hereditary AT-III deficiencyAnticoagulation / Thrombosis ProphylaxisHigh
- Pregnancy support in AT deficiencySupportiveHigh
- Prophylaxis of venous thromboembolismPreventionHigh
- Treatment of acute thromboembolism in hereditary AT-III deficiencyAnticoagulation / Thrombosis TreatmentHigh
- Obstetric thromboprophylaxis in AT-III-deficient patientsObstetric ManagementModerate
Contraindications
- Acquired AT-III deficiency without concurrent heparin resistanceClinical Indication MismatchModerate
- Hypersensitivity to human plasma-derived productsAllergy / ImmunologicHigh
- Severe uncontrolled hypertensionCardiovascularModerate
- Active bleedingHemostasisHigh
- Hypersensitivity to goat milk or goat milk proteins (ATryn only)Allergy / ImmunologicHigh
Adverse Effects
- Hypersensitivity reactionsImmunologicUncommon
- Hypersensitivity / anaphylaxisImmunologicalRare
- Injection site reactionsLocalCommon
- Dizziness / lightheadednessNeurologicUncommon
- Thromboembolic events (paradoxical)VascularRare
- Theoretical viral / prion transmission (plasma-derived only)InfectiousRare
- Chest tightness / dyspneaRespiratory / CardiovascularRare
- BleedingHematologicUncommonAbnormal bleeding or hemorrhage
- Infusion-site reactionsLocal / AdministrationUncommon
Drug Interactions
- HeparinModerate
- Direct oral anticoagulants (rivaroxaban, apixaban, dabigatran)Moderate
- Warfarin / vitamin K antagonistsModerate
- WarfarinLow
- Thrombolytics (alteplase, streptokinase)High
- Heparin (unfractionated or LMWH)High
Population Constraints
- PregnancyReproductive SafetyRelative
- Hepatic impairmentOrgan FunctionRelative
- Patients with known coagulopathy beyond AT-III deficiencyHematologic ComorbidityRelative
- Pediatric patientsAgeRelative
- Pregnant womenReproductiveRelative
Regulatory Status
- European UnionApprovedApproved: Hereditary antithrombin deficiencyEMA approval with similar labeling.
- United StatesApprovedApproved: Congenital antithrombin deficiency prophylaxisFDA approval for ATryn (recombinant ATIII).
- United KingdomApprovedApproved: Treatment and prophylaxis of thromboembolic events in hereditary antithrombin deficiencyRecognized post-Brexit; plasma-derived and recombinant formulations available under MHRA authorization.
Recombinant ATIII (ATryn) received FDA approval in 2005 for congenital AT deficiency; EMA approval for similar indications. Used under prescription and monitored for anticoagulant effect.
Evidence & Sources
- Journal ArticleLowTepper J, Schäfer R, Hoffmann A1995-01-01T00:00:00.000000Z
- Journal ArticleLowNunez H, Drohan WN1991-01-01T00:00:00.000000Z
- Journal ArticleLowMenache D, et al.1990-01-01T00:00:00.000000Z
Frequently Asked Questions
What clinical situations justify the use of antithrombin III?
AT‑III is primarily indicated for patients with hereditary AT‑III deficiency, especially when they face high‑risk events such as surgery, childbirth, or severe trauma that could trigger thrombosis. It may also be considered when conventional anticoagulants are insufficient or contraindicated.
How long does a single dose of antithrombin III remain active in the body?
In the studied patients, the half‑life ranged from about 43 to 77 hours, meaning therapeutic levels can persist for two to three days after a single infusion, though recovery may be lower in critically ill individuals.
Are there any known side effects or safety concerns?
The 1990 clinical evaluation reported no immediate adverse events, no hepatitis B seroconversion, and stable liver enzymes when AT‑III was given without other blood products. Nonetheless, rare allergic reactions or transmission of plasma‑borne pathogens remain theoretical risks with any plasma‑derived therapy.
Why is antithrombin III considered an expensive therapy?
Cost analyses of intensive‑care units identified AT‑III among the top ten cost‑driving blood products, reflecting its plasma‑derived nature, purification process, and frequent use in high‑risk bleeding or trauma cases.
What is Antithrombin III human?
Human antithrombin III (AT‑III) is a plasma‑derived serine protease inhibitor used as a prescription product to replace deficient AT‑III levels. It is administered intravenously or subcutaneously to patients with hereditary AT‑III deficiency or to reduce thrombotic risk during high‑risk situations such as surgery, childbirth, or severe trauma. The preparation is a purified protein derived from donor plasma and is listed among the most costly blood‑product drugs in intensive‑care settings.
What is Antithrombin III human used for?
Antithrombin III human is educationally associated with: Treatment of acute thrombotic events, DIC (disseminated intravascular coagulation) management, Perioperative thromboprophylaxis in AT-III-deficient patients, Prevention of thromboembolic events in hereditary AT-III deficiency, Pregnancy support in AT deficiency, Prophylaxis of venous thromboembolism, Treatment of acute thromboembolism in hereditary AT-III deficiency, Obstetric thromboprophylaxis in AT-III-deficient patients. Educational only — not medical advice.
How is Antithrombin III human administered?
Recorded routes of administration: Intravenous, Subcutaneous.
What are the potential side effects of Antithrombin III human?
Reported adverse effects include: Hypersensitivity reactions, Hypersensitivity / anaphylaxis, Injection site reactions, Dizziness / lightheadedness, Thromboembolic events (paradoxical), Theoretical viral / prion transmission (plasma-derived only), Chest tightness / dyspnea, Bleeding, Infusion-site reactions. This list is not exhaustive — consult a qualified clinician.
Who should avoid Antithrombin III human?
Recorded contraindications: Acquired AT-III deficiency without concurrent heparin resistance, Hypersensitivity to human plasma-derived products, Severe uncontrolled hypertension, Active bleeding, Hypersensitivity to goat milk or goat milk proteins (ATryn only). Consult a qualified clinician before use.