Flashcards in Anticoagulants Deck (23)
What do protein C and S do?
Cleave factor 5a and 8a to stop coagulation cascade
What is the structural features of heparin? route of administration, half life, cross placenta?
Large and water soluble
IV/short half life 2hrs
Do not cross placenta (too big)
What is the structural features of warfarin? route of administration, half life, cross placenta?
Small and lipid soluble
oral/long half life 30+hrs
Which is teratogenic, heparin or warfarin?
What is the MOA of warfarin?
Inhibit Vitamin K epoxide reductase--->prevent recycling of Vitamin K--->no effect on active Vitamin K--->thus slow onset
What is the MOA of heparin?
Bind to antithrombin III and activate it--->ATIII inactivate thrombin (factor 2)/9/10/11/12
What do we use to monitor heparin and warfarin?
Warfarin--->PT and INR
How to do rapidly counter warfarin?
Give fresh frozen plasma
How does protamine antagonize heparin?
Protamine bind to heparin and inactivate it--->chemical antagonism
What are the toxicities for heparin and warfarin?
Heparin--->heparin induced thrombocytopenia (HIT)/hypersensitivity
Warfarin---->skin necrosis/drug interaction/teratogen
Why do we use low molecular weight heparin and what are they?
Smaller--->longer half life/no need to monitor PTT
What drug would displace warfarin from protein binding and increase PT and INR?
What clotting factors do warfarin inhibit and why do we use heparin with warfarin in the beginning?
Factor 7 and C have short half life--->go away first--->transient hyper-coagulate state (skin necrosis)
How to treat HIT?
Stop heparin--->switch to direct thrombin inhibitors (argatroban/dabigatran/bivalirudin)
What else can bivalirudin used for?
What are direct factor 10 inhibitors and what are they used for?
Alternative to warfarin/prevent DVTs after surgery/prevent stroke and embolism from a fib
What are thrombolytics and what do they do?
tPA (tissue plasminogen activator)--->alteplae/reteplase/tenecteplase (teplase)
Convert plasminogen into plasmin to cleave fibrin and break the clot--->use acutely for MI/DVT/PE/stroke
What's the difference between tPA and streptokinase?
Streptokinase--->act on both bound and free plasminogen (not clot specific)/cause allergy
tPA--->act on only fibrin bound plasminogen/cause NO allergy
What are the antidotes for excessive bleeding from tPA or streptokinase? and how do they worK?
Antifibrinolysin--->aminocaproic and tranexamic acids
Stop the conversion from plasminogen to plasmin
What are the 3 classes of antiplatelet drugs?
Inhibit TXA2 (aspirin)
Inhibit ADP receptor (clopidogrel/ticagrelor/ticlopidine)
Inhibit GP2a3b receptor (abciximab/eptifibatide/tirofiban)
Which ADP receptor blocker has the side effect of thrombocytopenic purpura?
Ticlopidine--->thus not really used
How are ADP receptor block used?
Alternative to aspirin (post MI and unstable angina)