anticoagulation

Question 1

what is the mechanism of action of warfarin?

Answer 1

warfarin competitively inhibits the enzyme vitamin K reductase complex which activates the vitamin K available in the body to synthesise clotting factors

Question 2

give 3 side effects of warfarin?

Answer 2

dizziness, excess bleeding, bruising

Question 3

explain warfarin counselling?

Answer 3

taken at the same time every day, if a dose is missed can take within 12 hours but never double up on doses, it is normal to bleed more when taking an anticoagulant, but if a bleed lasts more than 10 minutes call an ambulance, avoid foods very high in vitamin K such as kale and broccoli, never binge drink (can effect INR), always inform the dentist before an operation, carry anticoagulant alert card and carry warfarin booklet

Question 4

explain the monitoring requirements for warfarin?

Answer 4

INR monitoring daily until target INR (2-3) is reached, then twice weekly for a few weeks, then once every few weeks

Question 5

what is used for the reversal of warfarin?

Answer 5

vitamin K

Question 6

how does aspirin work as an antiplatelet agent?

Answer 6

inhabits COX-1 so that thromboxane cannot be made to form platelets

Question 7

how does pulmonary embolism occur?

Answer 7

thrombus breaks off from a plaque travels in the pulmonary circulation causing vascular occlusion and a block of blood flow to the brain

Question 8

how can atrial fibrillation lead to a stroke?

Answer 8

atrial fibrillation can cause a build up of blood in the heart, this can form a thrombus and parts are able to break off and enter the ventricles and enter circulation, these can travel to the brain and block blood flow

Question 9

how do low molecular weight heparins work as anticoagulants?

Answer 9

activate antithrombin 3 which inactivates factor IIA, XA, IXA in the clotting cascade

Question 10

what does the chadsvas score determine?

Answer 10

weather to anticoagulate (clotting risk)

Question 11

what does the orbit score determine?

Answer 11

bleeding risk

Question 12

which 3 DOACS inhibit factor Xa and what does this cause?

Answer 12

apixaban, edoxaban, rivaroxaban, the inhibition of factor Xa prevents thrombin formation

Question 13

what is the mechanism of action of dabigatran?

Answer 13

reversible inhibitor of free thrombin, fibrin bound thrombin and thrombin induced platelet aggregation

Question 14

which anticoagulants have reversal agents?

Answer 14

warfarin, apixaban, rivaroxaban, dabigatran

Question 15

what is the ideal INR range for cardiac conditions?

Answer 15

2-3

Question 16

what is the ideal INR range for recurring AF or DVT?

Answer 16

3-4

Question 17

what to do if there is a major bleed when on warfarin?

Answer 17

stop warfarin, give vitamin K and dried prothrombin complex

Question 18

what are the monitoring requirements for DOACS?

Answer 18

U&E’s, LFT’s, FBC one month after treatment then once every few months after