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Anticoagulants
- Don't dissolve clots
- Reduce the ability of the blood to clot
- Prevent the formation of blood clots or the extention of an exsiting clot (which allows the endogenous thrombolytic system to work)
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Contraindications
- Ulcerative disease (Upper and lower GI, skin, arterial)
- Underlying coagulation disorders (hemophelia)
- Hemorrhagic stroke or hx of
- Liver impairment (synthesis center for clotting factors)
- Recent trauma/surgery
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Heparins
- Heparin is found normally in the body
- Is synthesized by mast cells
- Rx is extracted from bovine and porcine (must keep religious prohibitions in mind)
- Is given parenterally
- Acts rapidly once in the blood (SQ 20-30min)
- Is anticoagulant of choice fo pregnant women as it does not cross the placenta due to the long chain molecule.
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Two types of Heparin
Unfractionated and Fractionated (low molecular weight heparin)
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Unfractionated Heparin indications and uses
- Primarily inpatient
- Prophylacticly given pre-op, with dialysis,
- Also used with DVT's, PE's, A. Fib, MI, and Angioplasty
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Unfractionated Heparin general info
- Is a mixture of various molecular weights (multiple sizes of molecule)
- Route: Given parenterally
- Indications: Prevention of clot formation/extention by reducing the ability of the blood to clot
- Onset: IV = immediate; SQ = 20-30min
- Duration: IV = 2-6hr; SQ = 8-12hr
- Monitoring: Adjusted based on the aPTT (activated partial thromboplastin time). Normal aPTT is 25-35 sec. Therapeutic is 45-70 sec (1.5-2.5 x the baseline or control)
- Teaching: Report s/s of unusual bleeding; do not take NSAID's or Aspirin while on heparin therapy; use soft bristle toothbrush and electric razor; carry Medical Alert ID.
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Adverse effects of Heparin
- Bleeding: From gums, after shaving, from bumps and scrapes
- Heparin-induced thrombocytopenia (HIT): Antibody formation against the heparin causes a depressed paltelet count. Simultaneous bleeding and clotting (monitor platelet count (expect it to be low) and aPTT (it will be prolonged)).
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Unfractionated Heparin Mechanism of Action
- Inactivates several clotting factors (10A)
- Inhibits the conversion of prothrombin to thrombin (in the common pathway)
- Inactivates thrombin (in the common pathway)
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Low Molecular Weight Heparin (fractionated)
- Less varied mixture of molecular weights (Has been sorted to find low weight molecules)
- No routine lab monitoring of coagulation parameters (no routine aPTT)
- Do monitor stool occult blood, plateple counts, and s/s of bleeding
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Enoxaparin (Lovenox), Dalteparin (Fragmin)
- Advantages: Can take at home; no routine coag labs needed.
- Indications: Prevention of DVT, VTE (venous thromboemolis), and PE
- Route: SQ
- Onset: Dalteparin--Rapid; Enoxaparin--unkwn
- Duration: Dalteparin--up to 24hr; Enoxaparin--12hr
- Teaching: SQ injection technique; Report s/s of unusual bleeding; do not take NSAID's or
- Aspirin while on heparin therapy.
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Warfarin (Coumadin)
- Most commonly used oral anticoagulant.
- Indications: Prophylaxis tx of venous thrombosis, PE, A. Fib with embolization
- Route: Oral
- Onset: 36-72 hr
- Duration: 2-5 days
- Monitoring: Dosage is adjusted based on PT or INR; normal PT=12 sec, therapeutic=18 sec; normal INR=1, therapeutic=2-3. Notes changes in vit. K dependant clotting factors.
- Teaching: Report s/s of unusual bleeding; do
- not take NSAID's or Aspirin while on heparin therapy; use soft bristle
- toothbrush and electric razor; carry Medical Alert ID.
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Warfarin Mechanism of Action
- Acts on the liver to prevent synthesis of Vit. K dependant clotting factors (2,7,9,10)
- Takes 3-5 days to achieve anticoagulation as it does not act on clotting factors that have already been synthesized and are circulating.
- Metabolized by CYP450 enzymes.
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