lecture 9 - antiplatelets, anticoagulants & fibrinolytics Flashcards
What are the 3 key classes of anti-haemostatic agents?
Anti-platelets, Anti-coagulants, Fibrinolytics
What are the 2 most commonly used anti-platelet agents?
low dose aspirin, clopidogrel
What is the mechanism of action of oral low dose aspirin?
Is a non-selective COX inhibitor which irreversibly binds to COX, reducing thromboxane production which is required for platelet aggregation
What is the functional drug class of Clopidogrel?
Anti-platelet agent
What is the mechanism of action of clopidogrel?
Irreversibly inhibits ADP receptors, preventing ADP from activating platelets
What is the mechanism of heparin (unfractioned and low molecular weight)?
Reduce the formation of a fibrin clot by increasing the action of anti-thrombin III binding with Factor Xa and thrombin. This prevents the activation of fibrinogen to fibrin.
What is the drug target of heparins?
Anti-thombin III
What part of the coagulation cascade does heparin target?
Common pathway
What are the adverse reactions with heparin?
Thrombocytopenia, haemorrhage
What is the advantage of low molecular weight heparins over unfractioned heparins?
Fewer adverse effects, longer duration of action
What is a commonly used low molecular weight heparin?
Enoxaparin
What are the indications for low molecular weight heparin?
unstable angina, DVT prophylaxis/treatment, acute STEMI
What is the mechanism of action of warfarin?
Vitamin K antagonist: Irreversibly binds Vitamin-K-reductase which is required for the gamma-carboxylation of Factors X, IX, VII and II (prothrombin)
What are the adverse affects of warfarin?
haemorrhage, stroke, skin necrosis - all arise because warfarin has a very narrow therapeutic range
What INR range indicates that warfarin dosing should be ceased/adjusted/reversed?
INR > 4
