Types of Anticoagulants
An anticoagulant is a substance or agent that interferes, suppresses and/or prevents blood from clotting. The parenteral anticoagulants commonly prescribed and administered in a hospital setting include heparin and the most frequently prescribed oral anticoagulant is coumadin.
Anticoagulation medications don't dissolve any blood clots present. But they do stop the enlargement of existing clots and prevent the development of new ones. These agents exert their effects by interfering with some of the steps involved in the clotting cascade.
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Heparin and Its Indications
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Unfractionated heparin is a parenteral anticoagulant that prevents a stable fibrin blood clot from forming, by inactivating thrombin. It is used for treatment of venous thrombosis and its extension, pulmonary embolism, thromboembolic complications associated with atrial fibrillation and cardiac valve replacement and arterial thrombosis.
It is also used post MI, to reduce risk of death, recurrent MI and thromboembolic (clotting) events, such as stroke or systemic embolization (moving clot).
Furthermore, it is use for prevention of clotting during cardiac surgery and in dialysis procedures too.
Heparin Counterindications
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Contraindications to heparin therapy include bleeding/hemorrhage, heparin allergy, thrombocytopenia, allergy to beef or pork, purpura (bruising), intracranial hemorrhage, gastrointestinal bleeding and shock. Also, assessment for adverse reactions should include bleeding, thrombocytopenia (low platelet count), chills, fever and hives that could be due to a hypersensitivity reaction. In addition, shock may occur.
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Reversal of Heparin (Antidote)
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Protamine sulfate, a heparin antidote, will neutralize the effects of heparin if a heparin overdose is suspected. Approximately 1 mg of protamine will neutralize approximately 100 units of heparin. This medication must be administered via IV very slowly, and the dose should not exceed 50 mg in a 10-minute period.
Coumadin and Its Indications
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Coumadin is the approved oral anticoagulant and the mechanism of action includes direct inhibition of viatmin K dependent synthesis. It is used for the prophylaxis and or treatment of venous thrombosis, pulmonary embolism and atrial fibrillation. It is also used post MI to reduce death risk and further clotting events. It also helps reduce the risks associated with peripheral vascular disease.
Counterindications of Coumadin
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Coumadin is contraindicated in women who are or may become pregnant because the drug passes through the placental barrier and may cause fatal hemorrhage to the fetus in utero.
Coumadin Antidote
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Vitamin K laden foods (generally leafy green vegetables) and diuretics (increase clotting factor concentration) reduce the anticoagulant effect and hypothyroidism decreases anticoagulation effect.
FFP or fresh frozen plasma is indicated for the bleeding patient who cannot wait for the vitamin K to take effect. It should only be used in emergencies as there are risks associated with its transfusion.
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