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What is Heparin?
An acidic unfractionized mucopolysaccharide that inhibits blood coagulation potentiating the action of Antithrombin
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How is heparin given to a patient?
Must be given by injection
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Where is heparin inactivated in the body, how is it excreted, and what is its half life?
Inactivated by the liver and excreted in the urineHalf life of one hour
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How does heparin work as an anticoagulant?
- Enhances complexes between Antithrombin and activated serine proteases:
- Thrombin IIa, IXa, Xa, and XIa
- These complexes inactivate these serine protease factors
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List 5 points of Standard heparin.
- 1. Continuous intravenous infusion
- 2. Best for surgical patients or pregnancy
- 3. High molecular weight 30,000-40,000 units
- 4. Maintains a therapeutic anticoagulationMeasured by APTT
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List 5 points about Low Molecular Weight heparin.
- 1. LMWH is given as a subcutaneous injection
- 2. Longer half life than HMWH
- 3. Usually given once a day as a prophylaxis
- 4. Given as outpatient therapy as treatment for DVT
- 5. Reduces the risk of heparin-induced thrombocytopenia
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Why should a heparin IV be stopped immediately after a bleeding episode occurs?
Heparin has an anti-platelet function.
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What should you do if bleeding occurs following a subcutaneous injection of heparin?
- Protamine sulfate is given to inactivate heparin.
- Give 1mg of protamine for every 100 units of heparin
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What is a side effect of heparin administration that occurs within the first 24 hrs. Why?
- Heparin-Induced Thrombocytopenia
- * Mild lowering of platelets occurs in the first 24 hours of heparin administration
- *Usually due to platelet clumping
- *Heparin binds to platelet factor 4 following the generation of an IgG antibody against heparin
- *Antibody of the heparin-Platelet 4 complex leads to platelet activation, thrombocytopenia, and thrombosis
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What is warfarin aka Coumarin or Coumadin?
- 1. oral anticoagulant
- 2. vit k antagonist so decreases activity of factors II, VII, IX, and X
- 3. VII levels fall considerably w/in 24 hrs
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How long does it take warfarin to reach its full anticoagulant effect? Why?
Takes three days for full anticoagulant effect due to plasma half life of Prothrombin
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Describe the administration of an oral anticoagulant.
- *10 mg on day one, 5 mg on day two, 5 mg on day three, followed by PT monitoring
- *Adjustments should be made according to the PT result.
- *Maintenance dose ranges from 3-9 mg per day.
- *Lower loading dose is recommended for elderly patients
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What control tests strongly evaluate the therapeutic response to oral anticoagulation? What are the ranges for the tests?
- *INR and PT
- *Patients in recovery from DVT, pulmonary embolism or inherited thrombophilia should have a INR range from 2.0 to 3.0
- *Patients with mechanical heart valves should have a therapeutic range from 2.5 – 3.5
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What is Antiphospholipid Syndrome (APS)?
- 1. Persistence of an antiphospholipid antibody
- 2. Usually directed against GP 1B and Prothrombin
- 3. Lupus anticoagulant – Detected in patients with SLE
- 4. Associated with venous and arterial thrombosis
- 5. Autoimmune disorder of connective tissue
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When is APS usually seen, what is it associated with, and how is it treated?
- 1. Usually seen after a lymphoproliferative disorder, post-viral infections
- 2. Associated with arterial thrombosis (stroke and myocardial infractions), Placental infarctions, and abortions
- 3. Treat with oral anticoagulants and maintain an INR greater than 2.0
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