Flashcards in Anticoagulants Deck (56)
What are the categories of antithrombotics?
What do anticoagulants do?
Stop clot formation and extension
What do fibrinolytics do (in general)?
Break up existing clots
What do antiplatelets do?
Decrease platelet activation and aggregation
What are the two types of thrombi and how do they differ?
-White thrombus (platelet rich, forms in arteries, MI)
-Red thrombus (fibrin/RBC rich, forms in veints, DVT/PE)
What does TXA2 do?
What does vWF do?
Binds to exposed collagen fibers at the injured vessel surface
What does fibrinogen do?
-Forms bridges between adjacent platelets
-This results in an aggregate of platelets at the vessel injury site
What does thrombin (factor IIa) do?
Converts fibrinogen to fibrin (which forms the stable clot)
What is the final result of the coagulation cascade?
Fibrin threads create a plug to make a stable clot
What are the overall steps of platelet activation?
-Collagen and vWF exposed
-Platelet adherence and activation
-Binding of fibrinogen
-Aggregation and plug formation
What are the mediators of platelet aggregation?
What are the pathways of the coagulation cascade and how are they activated?
-Intrinsic (activated by exposed endothelium)
-Extrinsic (activated by tissue damage)
-Common (intrinsic and extrinsic merge together)
What is the first step in the common pathway of coagulation?
Activation of Factor Xa
What is the last step in the intrinsic and extrinsic pathways of coagulation?
Activation of Factor Xa
What factors are necessary to form a clot?
Factor 2 (prothrombin)
What does Factor Xa do in the coagulation cascade?
Combines with Factor 2 (prothrombin) to form thrombin
What factors are targeted by Warfarin?
Seven, Nine, Ten (0), Two
What does prothrombin time (PT) measure?
Activity of Factors 2, 7, 9, 10
What is INR?
-International Normalized Ratio
-Same as PT but standardized worldwide
What does PTT measure?
Activity of Factors 2, 5, 7, 9, 10, 11, 12
What is activated clotting time (ACT)?
-Same as PTT but used in invasive/operating procedures
-Quicker result turnaround
What are the indirect thrombin inhibitors?
How do indirect thrombin inhibitors act as anticoagulants?
Help antithrombin deactivate clotting factors
Heparin inhibits which clotting factors?
X and II
What is HIT?
-Heparin Induced Thrombocytopenia
-Antibody mediated adverse effect of heparin
-Strong a/w thrombosis
What are signs of HIT?
-Platelets fall more than 50% from baseline with nadir 20,000+
-Platelets start to fall on day 5-10 of therapy
-Thrombosis occurs while on heparin
-R/o other causes of thrombocytopenia
What is the treatment of HIT?
-Stop heparin, treat with IV direct thrombin inhibitor
-Do NOT give platelets
-Do NOT give warfarin until platelets return to normal
LMWH (enoxaparin) inhibits which factors?
Factors Xa, IIa