Antiplatelets And Anticoagulants Flashcards
In absence of vascular injury, these keep platelets from aggregating released by endothelium
NO - dilates blood vessel
Prostacyclin - binds to platelet receptors to prevent aggregation
Platelets adhere to exposed collagen via
von Willebrand Factor
Activated irregularly shaped platelets secrete granules that attract and activate even more platelets to site of injury
Platelet activating factor ADP Thrombin TXA2 Serotonin
Platelet receptor that binds to circulating fibrinogen
Fibrinogen binds to two separate platelets that form aggregates
GPIIb/IIIa
Platelet activation leads to formation of TXA2 from activation of arachidonic acid by COX -> PGH2 -> TXA2
Irreversibly inactivates COX1 enzyme thus effectively disruptiong clot formation
Aspirin
Blocks action of the ADP receptor P2Y12 subtype on PLATELET
Prevents binding of ADP to P2Y12 receptor leading to inactivation of GPIIb/IIIa receptors that bind to fibrinogen to promote cross-linking
ADP P2Y12 inhibitors
Clopidogrel
Prasugrel
Ticagrelor
Ticlodipine
Blocks GPIIb/IIIa receptors on PLATELET so it will not bind to fibrinogen and will not cross link
Administered only IV
Abciximab
Eptifibatide
Tirofiban
Phosphodiesterase inhibitors responsible for breaking down cyclic AMP to AMP
Blocking phosphodiesterase
INC intracellular levels of cAMP
DEC intracellular Calcium
Inhibition of platelet activation
PDE inhibitors
Dipyridamole
Cilostazol
Also inhibits PDE in the vascular wall and
Inhibits uptake of adenosine leading to VASODILATION
Hence used for PAD (narrowing of vessel)
Cilostazol
SE: headache
Antiplatelets
Aspirin
ADP P2Y12 inhibitors (Clopid, Prasu, Ticlodipine, Ticagrelor)
GPIIb/IIIa inhibitors (Abciximab, Eptifibatide, Tirofiban)
PDE inhibitors (Cilostazol, Dipyridamole)
SE: bleeding, headache
Binds to Anti thrombin III to inactivate Factor Xa and Thrombin
Accelerates Anti thrombin III
Heparin
Selectively accelerate inactivation of Factor Xa
Low molecular weight heparin
Enoxaparin
Dalterparin
No direct effect on thrombin
Selectively binds to Anti thrombin III thereby inhibiting factor Xa ONLY
Related to LMWH
Fondaparinux
Binding to heparin or LMWH to form stable inactive complex
Reverses excessive bleeding caused by heparin drugs
Protamine sulfate
Heparin SE
Antibodies made against heparin when it is bound to platelet derived protein called Platelet Factor-4
Platelets clump together form unwanted clots
Heparin-induced thrombocytopenia
Direct inhibitors of Factor Xa
Bind directly to active site of Factor Xa preventing it from converting
Prothrombin -> Thrombin
Oral
Apixaban
Rivaroxaban
Direct thrombin inhibitors
Univalent direct thrombin inhibitors (bind only to active site)
Bivalent Direct thrombin inhibitors (both active site and exosite-1 fibrinogen binding site)
Univalent Direct Antithrombin drugs
Argatobran
Dabigatran
Bivalent direct antithrombin
Bivalirudin
Desirudin
Direct antithrombin inhibitors are useful in treatment of heparin induced thrombocytopenia because they do not bind to
PA F4
Decreases Vitamin K that carboxylases Factors 1972
Inhibits Vitamin K epoxide reductase disrupting Vitamin K dependent synthesis of coagulating factors
Narrow therapeutic windows
Many drug-drug interactions
Monitor with PT and INR
Warfarin
Overcomes Warfarin induced bleeding but takes 24 hours
Vitamin K
If emergency transfuse FFP
Act on existing clot causing it to dissolve by activating Plasminogen turning them into plasmin
Plasmin is the enzyme that breaks fibrin molecules dissolving clot
SELECTIVE to FIBRIN BOUND PLASMINOGEN, CLOT SELECTIVE DISSOLVES FIBRIN IN THROMBUS
Developed by DNA recombinant technology to mimic TPA
Alteplase
Reteplase
Tenecteplase
Thrombolytic produced from culture human kidney cell
Less clot selective and are more likely to cause internal bleeding into any organ system
Urokinase
Thrombolytic from streptococcal bacteria
Less clot selective and are more likely to cause internal bleeding into any organ system
Streptokinase
Antidote to thrombolytic bleeding
Inhibits plasminogen so plasmin will inactivate fibrinolysis
Aminocaproic acid
Tranexamic acid
