Antithrombotics (DOACs, Heparins, Antiplatelets etc.)

Question 1

What is the MOA of DOACs?

Answer 1

Rivaroxaban, Apixaban, Edoxaban Directly inhibiting Factor X (Xa) and therefore inhibit

Dabigatran inhibits thrombin

E.g. Apixaban, Rivaroxaban

Question 2

What are the most common indiciations for DOACs?

Answer 2

1. AF to prevent stroke
2. Treatment and prevention for VTE

Question 3

What are the main contraindications to DOACs?

Answer 3

1. Active clinically significant bleeding
2. Risk factor for major bleeding (e.g. peptic ulcers, recent surger, stroke)
3. Pregnancy

Question 4

What are common drug intteractions with DOACs?

Answer 4

Other antithrombotic medication: bleeding

Enzyme inducers/inhibitors or way of excretion

• Anticoagulation is decreased by refampacin and phenytoin (absoloute contraindication)
• anticoagulation is increased by macrolides)

Question 5

What is important to communicate when prescribign DOACS?

Answer 5

1. Risk of bleeding
2. Important to take at same time due to short half life
3. Must be taken with food otherwise reduced absorption and not effective

Question 6

INR between 5-8 and no bleeding

Answer 6

withhold 1 or 2 doses of warfarin and reduce subsequent maintenance dose.

Question 7

INR 5-8 with minor bleeding

Answer 7

Stop warfarin, give phytomenadione by slow intravenous injection; restart warfarin when INR <5

Question 8

Major bleeding on warfarin

Answer 8

Stop warfarin, give phytomenadione by slow intravenous injection; give dried prothrombin complex

Question 9

INR > 8 and there is minor bleeding.

Answer 9

Stop warfarin, give phytomenadione by mouth; restart warfarin when INR <5

Question 10

What is the threshold for blood transfusion (in anaemia)?

Answer 10

A threshold of 70 g/L is used when using a restrictive transfusion threshold.

Higher thresholds (usually 80 g/L) are used in acute coronary syndrome and restrictive transfusion is not used in cases of major haemorrhage.