The use of heparin is prophylactic. It is used either to prevent thromboembolism (a condition in which a blood clot forms inside a vessel and becomes dislodged), or used to limit a previous thromboembolism. Other key points about heparin include:
- Heparin inhibits thrombin. The degree of inhibition is dosage dependent.
- Low doses of heparin inhibit initial thrombin formation in the coagulation cascade, and act to slow down overall thrombin generation.
- At higher doses, heparin can inhibit thrombin entirely, making blood coagulation impossible.
- Heparin is a potent anticoagulant. Accurate monitoring is essential.
The activated partial thromboplastin time (APTT) and/or activated clotting time is used to monitor unfractionated heparin therapy.