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34 Cards in this Set
- Front
- Back
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What conditions are associated with arterial vs venous thromboses?
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arterial - hypertension, turbulent blood flow, atherosclorosis
venous - venous stasis |
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How do thromboses cause disease?
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arterial thromboses usually cause ischemia or infarction via obstruction
venous thromboses are more likely to cause formation of an 1. embolus because they easily detach, and also causes 2. congestion of flow leading to edema and/or inflammation (DVT and thrombophlebitis) |
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What are pharmacological treatments or preventions for thromboses?
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anticoagulants - stop formation of new clots - interrupts clotting cascade
antiplatelets - prevents platelets from adhering to vessel thrombolytic - dissolves thrombi |
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Explain physiological process of clotting.
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Hemostasis Stage 1 - formation of platelet plug
- platelets adhere to damaged vessel and creates a plug to stop bleeding - factors like ADP, thrombin, PAF, and TXA2 (thromboxane) are released from platelets, resulting in opening of receptors for fibrinogen Hemostasis Stage 2 - fibrin binds and reinforces platelet plug - fibrin is activated by intrinsic or extrinsic pathway (coagulation cascade) |
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How is coagulation regulated by the body?
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antithrombin - inactivates clotting factors, preventing excess of clots
plasminogen --> plasmin -- enzyme digests fibrin |
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Basically, what is Heparin?
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fast acting anticoagulant
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Is heparin safe for pregnancy?
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yes. large size cannot cross barriers. also safe for breastfeeding.
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What is the mechanism for heparin?
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1. inhibit activity of Factor X in platelet cascade (interrupts conversion of proth to thromb)
2. inhibit activity of fibrin |
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indications for heparin?
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those requiring fast acting anticoagulant:
- DVT - PE - pulm embol - DIC - stroke - acute MI - open heart surgery, renal dialysis |
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What is DIC?
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Disseminated intravascular coagulation - clots throughout body, using up clotting factors resulting in possible bleeding out
treat with heparin |
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What are adverse effects of heparin? drug interactions?
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hemorrhage, as with all coagulation modifiers
heparin induced thrombocytopenia hypersensitivity should not be used with antiplatelets because pt. will no longer have any defense against hemorrhage |
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Contrainidications for heparin?
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- thrombocytopenia, bleeding disorders (with the exception of DIC)
- eye, spinal cord, brain surgeries - patients that are likely to bleed |
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What is aPTT?
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activation partial thromboplastin time = amt of time it takes for thrombin to be activated
used as a measure for effect of heparin normal = 40 sec heparin normal = 60-80 above 80 - contact physician |
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What is important to do before administering heparin?
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check aPTT one hour before administration (only if intermittent administration, obvi)
nrmal - 40 sec heparin normal - 60-80 above 80- contact dr. also check hematrocrit, and platelet count also very impt to check dosage because of deadly consequences |
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What is the antidote for heparin? how much should be used?
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protamine sulfate
1 mg for 1000 units of heparin |
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important points to know about Warfarin
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LP - KIX
L - leafy vegetables contain vit K P - PT/INR tests necessary for therapeutic dosage K - inhibits vit K synth. Vit K is antidote for OD. I - drug with most drug interactions X - Category X for pregnancy (very teratogenous, and also through milk ducts) |
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basically, what is warfarin?
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anticoagulant used for long term prophylaxis
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What is PT and INR? what are normal values?
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PT or prothrombin time is amount it takes for blood to clot
- used to gauge therapeutic dose for warfarin, whereas aPTT is used for heparin INR or intern'l normalized ratio is the ratio of the pt's PT to a stnadardized value for PT. normal is 1. when on warfarin, it is 2-3.5. |
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What is the antidote for coumadin?
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vit K
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coumadin aka
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warfarin
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What is coumadin's mechanism of action?
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inhibits bacterial synthesis of Vit K, which then inhibits synthesis of Vit K dependent clotting factors
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T or F. Patients should eat less leafy green vegetables when taking warfarin.
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F. leafy green vegetables containing vit K do reverse effects of warfarin, however, pt's should maintain same diet of these veggies while warfarin is adjusted to compensate.
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Which anticoagulant(s) are safe for pregnant women?
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heparin or Lovenox (LMWH)
warfarin (coumadin) is category X |
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What drug is used for anticoagulation in patients with HIT?
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HIT = heparin induced thrombocytopenia
Direct thrombin inhibitors, such as Bivalirudin (Angiomax), don't affect platelet levels, so applicable for HIT. |
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Name the kinds of antiplatelet drugs, and basic mechanisms.
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Aspirin (ASA) - inhibits cyclogenase, an enzyme requ for synth of Thromboxane A2 (platelet aggreg and vasoconstrction)
ADP receptor antagonist - inhibits ADP mediated binding of fibrinogen and GP IIb/IIIa (platelet aggregation) GIIb/IIIa receptor antagonist - same as above |
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What is thromboxane A2 role iin clotting?
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platelet aggregation, and vasoconstriction
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role of ADP in clotting?
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mediates binding between fibrinogen and GPIIb/IIIa
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What is GPIIb/IIIa?
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glycoprotein receptor IIb/IIIa - receptor on platelets that bind to fibrinogen to form fibrin meshwork, creating last step in hemostasis
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These are the most effective antiplatelets
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super aspirins aka GP IIb/IIIa receptor antagonists
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What is Plavix? similar drugs?
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cloPIDogrel (plavix) - ADP rececptor antagonist (anticoagulant)
similar - ticloPIDine (ticlid) |
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this enzyme digests fibrin matrix of clots
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plasmin
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What is mechanism of thrombolytics?
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promotes conversion of plasminogen to plasmin
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Name the kinds of thrombolytics
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places and kinases
alteplase, reteplase, tenecteplase streptokinase, urokinase (no longer used) |
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This is only drug approved for ischemic stroke
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alteplase - a tissue plasminogen activator (thrombolytic)
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