- Mechanism of Action
- Binds to and activates antithrombin III, which as a heparin-ATIII complex inactivates factor Xa
- Pharmacology
- More potent (2-4x) than unfractionated heparin due to higher activation of antithrombin III
- Smaller molecules are able to bind primarily to factor Xa, with little effect on IIa
- Better bioavailability and more predictable response than heparin
- Effective half-life is 4 hours.
- Reversed with protamine sulfate, though less effectively than with unfractionated heparin)
Clinical Use
- Indications
- Prevention of venous thromboembolism (DVT / PE)
- Treatment of venous thromboembolism (DVT / PE)
- ST elevation myocardial infarction (STEMI)
- Bridging anticoagulation for initiation / withholding of warfarin
- Prevention of thrombosis during haemodialysis
- Acute limb ischaemia (unfractionated heparin)
- Adverse Effects
- Haemorrhage
- Hypersensitivity
- Elevated LFTs
- Thrombocytopaenia (less commonly than heparin)
- Monitoring
- Not monitored in most cases, though anti-factor Xa levels may be taken.
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