Cardio: Anti-platelets + Anti-coagulants Flashcards
What is the aim of anti-platelets + anti-coagulants?
To prevent new thrombosis
Give examples of anti-platelet drugs
Aspirin
Clopidogrel
Tirofiban
What is the mode of action of aspirin?
Irreversibly inhibits COX enzyme which stops formation of thromboxane A2 (TXA2) - a mediator for platelet aggregation + clot formation
What is the mode of action of clopidogrel?
Blocks P2Y12 receptors to prevent ADP (a mediator for platelet aggregation) binding
What is the mode of action of tirofiban?
Prevents conversion of fibrinogen to fibrin
What is the main side effect of aspirin?
Peptic ulcers
What is the clinical use of tirofiban?
Prevention of MI in patients with unstable angina
What is the main clinical use of aspirin?
Prophylaxis of MI in high risk patients
Give examples of anti-coagulants
Warfarin
Heparin
Riveroxiban
What is the role of vitamin K reductase in coagulation?
Converts vitamin K from its oxidised to reduced form
What is reduced vitamin K required for?
Gamma carboxylation of precursors 2,7,9,10 into serine proteases
What is the mode of action of warfarin?
Inhibits vitamin K reductase enzyme
How can a high dose of warfarin be counteracted?
Vitamin K
What are the clinical uses of warfarin?
DVT
Prevention of thrombosis in AF
Prevention of thrombosis in patients with prosthetic heart valves
What drug can be added to the dose of warfarin to rapidly produce anti-coagulant effect?
Heparin
What are the potential side effects of warfarin?
Haemorrhage
Dizziness
What is the mode of action of heparin?
Binds to antithrombin III to increase rate of inactivation of clotting factors IIa and Xa
To which molecules must heparin bind in order to inactivate factor IIa (thrombin)?
Antithrombin III + thrombin
To which molecules must heparin bind in order to inactivate factor Xa?
Antithrombin III only
What do low molecular weight heparins inhibit?
Factor Xa
How are low molecular weight heparins excreted?
Via kidneys - NOT used in renal failure
What does riveroxiban directly inhibit?
Factor Xa
What are the clinical uses of riveroxiban?
Used after hip/knee surgeries to prevent venous clot
What are some of the side effects of anti-coagulants?
Haemorrhage
Osteoporosis
Hypoaldosteronism
What is the mode of action of thrombolytic drugs?
Activate plasminogen to plasmin (opposes coagulation cascade)
Give examples of thrombolytic drugs
Streptokinase
Duteplase
When are thrombolytic drugs used?
In an acute MI not treated with PCI within 90 mins
In massive PE’s
How can haemorrhage caused by thrombolytic drugs be countered?
Tranexamic acid
