Antithrombin III
Antithrombin III is a plasma-derived protein replacement therapy that provides the natural anticoagulant missing in patients with hereditary or acquired antithrombin deficiency. It is used to prevent and treat potentially life-threatening blood clots in high-risk situations such as surgery, pregnancy, or childbirth. This medication is administered intravenously in healthcare settings under medical supervision.
Antithrombin III replacement therapy treats and prevents blood clots in patients who lack sufficient natural anticoagulant protein.
Key facts at a glance
- ATC
- B01AB02
- RxNorm
- 1009
- Generic
- Antithrombin Iii
- Class
- atc-b01
- Brands
- Thrombate III, ATryn
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- injection
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Dosage and administration
- Usual dose
- 25-50 IU/kg initial dose
- Maximum
- consult physician
- Frequency
- as needed based on ATIII levels
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 25-50 IU/kg
- Maximum
- consult physician
- Frequency
- as needed based on ATIII levels
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
- Usual dose
- 25-40 IU/kg
- Maximum
- consult physician
- Frequency
- as needed with careful monitoring
- Instructions
- Follow physician instructions
- Duration limits
- as prescribed
- Monitoring
- standard
Overdose information
Special Populations
7 groupspregnancy
first trimesterindividualize dose based on AT activity levels
use only when benefits clearly outweigh risks
regular fetal monitoring and maternal AT activity levels
Use with caution and monitor for adverse effects.
pregnancy
third trimesterindividualize dose based on AT activity levels
commonly used during delivery in AT-deficient mothers
close maternal and fetal monitoring during labor
Use with caution and monitor for adverse effects.
lactation
breastfeedingno adjustment needed
generally considered compatible with breastfeeding
no specific monitoring required
pediatric_age
neonates infantsdose based on weight and AT activity level
use in congenital AT deficiency with careful monitoring
frequent AT activity monitoring and bleed assessment
Use with caution and monitor for adverse effects.
geriatric
elderly over 65consider reduced dose and extended infusion time
use with caution due to increased bleeding risk
close monitoring for bleeding and AT activity levels
Use with caution and monitor for adverse effects.
renal_impairment
moderate severemonitor renal function and adjust dose if needed
use with caution in patients with creatinine clearance <30 ml/min
monitor renal function and for signs of bleeding
Use with caution and monitor for adverse effects.
hepatic_impairment
moderate severeuse with caution may require dose adjustment
use cautiously in hepatic impairment due to altered protein synthesis
monitor liver function and AT activity levels
Use with caution and monitor for adverse effects.
Statistics and clinical data
Commonly prescribed since
General prescribing information
Drug class
Drug class information
Common uses
Common therapeutic uses
Treatment and prevention of thromboembolic events in patients with hereditary antithrombin deficiency, particularly during high-risk situations such as surgery, pregnancy, labor, and delivery. May also be used for acquired antithrombin deficiency associated with conditions such as disseminated intravascular coagulation (DIC), liver disease, or nephrotic syndrome.
Antithrombin III is a naturally occurring inhibitor of thrombin and other coagulation factors (IXa, Xa, XIa, XIIa). Replacement therapy increases plasma antithrombin levels, restoring the body's ability to regulate blood clot formation. The medication's anticoagulant effect is enhanced by heparin.
Administered by intravenous infusion under medical supervision. Regular monitoring of antithrombin levels, coagulation parameters, and for signs of bleeding or thrombosis is essential. Hypersensitivity reactions may occur. Must be stored properly and used as prescribed by a healthcare provider.
Contraindications
Conditions and patient states where this medication should be avoided or used with caution.
Do not use (1)
Known allergy to this medication or its components
Use caution (1)
Consult healthcare provider for benefits vs risks assessment
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 24, 2026. · Read our editorial policy