Anti-Coagulant Therapy Flashcards
Which clotting factors does warfarin therapy affect?
II, VII, IX, X
What is the action of anticoagulants?
Targets formation of the fibrin clot
Give indications for anticoagulant therapy
VT
AF
How soon does heparin show an effect?
Immediately
How does unfractionated heparin work?
Keeps anti-thrombin and thrombin bound together
How does LMWH heparin work?
Binds to thrombin to switch off factor Xa
How long does warfarin take to work?
7 days
How is heparin monitored?
APPT
Anti-Xa assay
How is LMWH monitored?
Not req’d
A prolonged PT in heparin used suggests what?
over-coagulation
How is warfarin therapy monitored?
INR
Where is heparin made in the body?
Mast cells
What does a sharp drop in platelets on heparin therapy indicate?
Autoimmune consumptive thrombocytopenia
How long does the effect of LMWH take to wear off?
12-24 hours
What can be given in severe bleeding in patients on unfractionated heparin?
Protamine sulphate
What does protamine sulphate do?
Reverse the antithrombin effect of heparin by “switching off” heparin
Give examples of coumarin anticoags?
Warfarin
Phenindone
What is the action of coumarin anti-coags?
Inhibit vitamin K synthesis
Where is vitamin K absorbed?
Upper intestine
Why is carboxylation important in factors II, VII, IX, X synthesis?
Adds COOH group which binds to calcium to attract platelets
Which enzyme metabolises warfarin?
Cytochrome P450
Which coag factor has the shortest half life?
Factor VII
What are the adverse effects of warfarin?
Bruising
Epistaxis
Haematuria
GI or cerebral bleeds
If there INR is too high on warfarin, but under 6, what action should be taken?
Miss a few doses of warfarin
If the INR is over 8 on Warfarin therapy what action should be taken?
Give vit K
How long does vit K take to work in reversal of warfarin therapy?
6 hours
What can be given in high INR and emergency/severe bleed to reverse warfarin therapy?
Factor concentrates
How long do factor concentrates take to reverse warfarin therapy?
Immediate action
Give examples of Xa inhibitors?
Rivaroxaban
Edoxaban
Apixaban
Give examples of direct thrombin inhibitors?
Dabigatran
How is dabigatran excreted?
Renally
What is the downside to new oral anticoags?
No reversal
