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- 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)
- 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
- 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.
Two types of Heparin
Unfractionated and Fractionated (low molecular weight heparin)
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
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.
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)).
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)
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
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.
- 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.
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.