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24 Cards in this Set
- Front
- Back
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What is the difference between:
1. Anticoagulants 2. Fibrinolytic Agents 3. Antiplatelet Agents |
Anticoagulants - drugs that inhibit thrombin or Xa, or decrease level of competent prothrombin/other zymogens
Fibrinolytic Agents - accelerate degradation of existing fibrin clots Antiplatelet - inhibit platelet plug formation |
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What factors does unfractionated heparin inactivate?
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Serine proteases:
IIa (thrombin), VIIa, Xa, IXa, XIa, XIIa |
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To what molecule does Unfractionated Heparin bind to inactivate both Thrombin (IIa) and Xa?
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Anti-thrombin III
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How is unfractionated heparin administered / how often?
LMWH? |
unfractionated heparin: IV or SQ - short half life so given frequently
LMWH: SQ, longer half life thus can be given only 1/2x daily |
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What is an toxic conditions associated with Heparin?
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Heparin Induced Thrombocytopenia (HIT) / Heparin-Associated Thrombocytopenia with Thrombosis (HATT)
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What is the mechanism of HIT/HATT?
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HATT: Antibodies that recoginize the heparin/PF4 (platelet protein) complex bind to platelet Fc receptors, triggering platelet activation
GET PLATELET ACTIVATION AND CLUMPING |
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How is HATT treated?
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1. Stop Heparin (duh)
2. Anticoagulate with thrombin inhibitor that doesn't look like heparin (lepirudan/argtroban) |
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What does Low Molecular Weight Heparin (LMWH) inhibit?
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Inhibits factor Xa
- Does not inhibit thrombin like unfractionated heparin does |
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What are 2 new direct thrombin inhibitors?
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1. Lepirudin
2. Argatroban BOTH CAN BE USED IN THE CASE OF HATT/HIT |
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What are 3 factor Xa inhibitors?
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1. Rivaroxiban (direct) - orally active
2. Apixaban (direct) - orally active 3. Fondaparinux (indirect) Note: All have X in their name |
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What is the mechanism of Warfarin (coumadin)?
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Inhibits recycling of Vitamin K
- Thus inhbits Vit. K dependent factors: II (thrombin), VII, X, IX Protein C/S |
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What are 2 possible drug interactions with Warfarin (coumadin)?
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1. Warfarin binds to albumin. Thus, other drugs that bind to albumin increase amount of free Warfarin
2. Drugs that increase P450 (system that deactivates drugs in liver) decrease effects of warfarin |
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What is the main advantage of Warfarin over Heparin?
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Orally active and can therefore be easily used in an outpatient setting
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When factor sythesis stops because of Warfarin (inhibit Vit. K), which factor will fall first?
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VII because shortest half life (4-5 hours)
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What is an INR?
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International Normalized Ratio
- Normalized measure of PT (2-3 is normal) |
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What complication can Warfarin sometimes cause?
Why? |
Can cause skin necrosis
Caused by transient pro-coagulant state because protein C levels fall first THIS IS WHY HEPARIN IS USUALLY STARTED FIRST |
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What is the main fibrinolytic enzyme in the body?
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Plasmin (comes from plasminogen)
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What are 3 examples of plasminogen activators?
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1. Urokinase
2. Recombinant t-PA (tissue - Plasminogen activator) 3. Streptokinase |
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What are the steps in normal treatment of a venous thrombosis?
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1. Start with a plasminogen activator if life threatening
2. Start with unfractionated heparin with loading dose, followed by continuous infusion (or use LMWH) 3. Start coumadin shortly after heparin 4. Maintain on coumadin for outpatient Tx |
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What are the 3 sites of action for platelet blockers?
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1. Receptor Antagonists
2. Signaling Blockers (within the platelet) 3. Integrin αIIbβ3 blockers |
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In platelet inhibition, what receptor/ligand do clopodogrel and prasugrel inhibit?
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Inhibit ADP (ligand) and P2Y12 (receptor for ADP)
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What are the Thrombin receptors on platelets?
What drug inhibits this receptor? |
PAR-1 and PAR-4
Vorapaxar inhibits |
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What are the 2 signaling blocking (within platelet) platelet inhibitors?
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1. Aspirin (inhibits TxA2 formation which recruits platelets to the plug)
2. Dipyridamole (inhibit cAMP PDE causing cAMP to accumulate and inhibiting platelet activation) |
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What are the 3 αIIbβ3 antagonists?
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1. Abciximab
2. Epifibatide 3. Aggrastat |
