Anticoagulants Flashcards
What is haemostasis and what are the three stages of it? (4 marks)
haemostasis is the stopping of bleeding
1. vascular spasm
2. platelet aggregation and plug formation
3. coagulation
At what stage of haemostasis do antiplatelets treat? (1 mark)
platelet aggregation and plug formation
At what stage of haemostasis do anticoagulants treat? (1 mark)
coagulation
What does thromboxane do? (1 mark)
Promotes platelet aggregation and causes vasoconstriction
what does prostacyclin do? (1 mark)
inhibits platelet aggregation and causes vasodilation
What is the MOA of low dose aspirin? (3 marks)
inhibits COX 1 and the production of thromboxane thus reducing platelet aggregation
Which COX cannot regenerate due to platelets not having a nucleus? (1 mark)
COX1
What can vascular tissue regenerate?
COX 1 and 2
Name 3 conditions which anticoagulants treat (3 marks)
DVT, PE, AF, prevent venous thromboembolic events after procedures or immobility
What can a thrombi or emboli lead to? (4 marks)
MI, ischaemic stroke, DVT and PE
What is the MOA of heparin? (3 marks)
combines antithrombin III and enhances rate that it inhibits thrombin IIa and activated factor X
What clotting factors does Warfarin indirectly inhibit and what does this cause? (5 marks)
Vitamin K clotting factors (2, 7, 9 and 10)
This causes delayed anticoagulant activity
What enzyme does warfarin inhibit?
Vitamin K epoxide reductase
What in the target INR for someone with Warfarin? (1 mark)
2-3
What does the INR do? (1 mark)
evaluates the extrinsic pathway of coagulation
What are some practice points for someone on warfarin?
consume at least 200mcg od Vitamin K a day
Continue to monitor
look out for warning signs of bleeding
Drug interactions with Ibuprofen, St Johns Wort and Ginko biloba
What are two antidotes for warfarin? (2 marks)
Vitamin K and fresh frozen plasma
What is dabigatran? (3 marks)
competitive, reversible and direct inhibitor of thrombin
what is apixaban and rivaroxaban? (3 marks)
direct, reversible inhibitor of factor X
What are 3 practice points for warfarin? (3 marks)
it is fast acting (within 30 minutes)
no ongoing monitoring needed
watch for warning signs of bleeding
contraindicated in prosthetic heart valves
must be dispensed and stored in original packaging
What is the antidote for dabigatran and what makes it so effective? (2 marks)
Idarucizumab, it has a 300 times greater affinity for dabigatran than thrombin
What is the antidote for rivaroxaban and apixaban? (1 mark)
there are no antidotes
