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Anticoagulants
drugs that prolong the bodys ability to form a thrombus (clot) at different points in the coagulation cycle.
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Intrinsic pathway and coagulation
Caused from peripheral vascular damage
coagulation inhibited by components entirely contained within the vasculature.
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Goal of anticoagulant therapy
promote anticoagulation while minimizing hemorrhagic complications through careful monitoring.
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Heparin MOA
TEST ????
no effect on existing clots- prevents formation of new thrombi
Binds with antithrombin III at two sites, first site has effect on factor x, and second site binding occurs at conversion of prothrombin to thrombin. TEST ???
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Clotting factors have different half lives.
Which has shortest?
Longest?
Factor VII - 6-9 hours
Factor II and X- up to 72 hours
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What is gold standard for monitoring anticoagulant treatment
INR
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Dosage of warfarin
- long half life but narrow therapeutic window
- begin at 2.5- 5 mg daily
Range is 1-15 have to individualize dose
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Acceptable INR in DVT
2.0-3.0
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INR prevention of recurrent thrombosis
2.0-3.0
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INR with cardiac valve replacement
tissue
mechanical
- tissue valve 2.0-3.0
- Mechanical valve 2.5-3.5
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INR recurrent systemic embolism
2.5-3.5
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MOA of aspirin (platelet aggregator)
- inhibits cyclooxygenase in platelets and endothelial cells, preventing synthesis of thromboxane and prostacyclin.
- -both are potent platelet aggregators and vasoconstrictors.
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Hold warfarin if INR is greater than
5
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ASA is used prophylactically to
TEST???
decrease incidence of MI/deaths in men > 50 years old. Treat unstable angina, non Q-wave infarction, and acute MI or CV
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Monitoring of Warfarin
- Recommended dose 5-10 mg
- Decrease dose in elderly, usually in half
- Monitor INR every 2-3 days until goal is reached, then weekly, then every 2 weeks, then finally monthly when stable dose and stable INR
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Warfarin pregnancy category
x
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Most common problem in patients on aspirin taking NSAIDs is
GI Bleed
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