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To which class of drugs does heparin belong?
What are the indications associated with heparin?
Prophylaxis and treatment of thromboembolic disorders.
What is unique about the chemical structure of heparin?
It is an extremely large (6,000 - 20,000 D), highly sulfated, negatively charged sugar.
Must be administered IV.
What is heparin's target MOA?
Heparin potentiates the action of antithrombin by acting as a catalyst for antithrombin-dependent deactivation of thrombin and other clotting factors.
As per heparin's MOA, what effects does it have on the body's tissues?
- Inactivation of thrombin (IIa), IXa, Xa, XIIa, and plasmin.
- Ultimately, the conversion of fibrinogen to fibrin is prevented.
- LPL is stimulated, resulting in increased FFA.
Heparin increases the activity of antithrombin by _______ x.
Heparin increases the natural activity of antithrombin (a hepatic enzyme) by about 1,000 x.
What are some adverse effects associated with heparin?
- HIT (1-2% incidence): heparin binds to platelet factor 4, and an immune response ensues against platelets. Antibody-platelet complexes aggregate and can cause, thrombosis and/or tissue death.
- Thrombosis (if body-stores of antithrombin run out).
What drug may be used as an antidote to heparin overdose (which would actually cause thrombosis)?
What lab parameter should be monitored to check for heparin efficacy/toxicity? What is its normal value? Is it desirable to be within this normal value?
- Normal value: 26-33 seconds
- Technically, you would want the aPTT to be above this value.
What lab parameters would indicate that a patient is experiencing bleeding and should not receive heparin?
Hgb, Hct, fecal occult blood test.