Anticoagulation

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 rifampacin and phenytoin(enzyme inducers) (absoloute contraindication)
• anticoagulation is increased by macrolides (enzyme inhibitors)

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

What is the definition of a Major haemorrhage on anticoagulation?

Answer 6

1) fatal
2) a fall in hemoglobin level of 2 g/dL or more or documented transfusion of at least 2 units of packed red blood cells
3) (b) involvement of a critical anatomical site (intracranial, spinal, ocular, pericardial, articular, intramuscular with compartment syndrome, retroperitoneal)

Question 7

What is the management of major bleeding in a patient on Warfarin?

Answer 7

1) stop warfarin sodium
2) give phytomenadione (vitamin K1) by slow intravenous injection
3) give dried prothrombin complex (factors II, VII, IX, and X); if dried prothrombin complex unavailable, fresh frozen plasma can be given but is less effective)

Question 8

What is the management of an INR of 5-8 but without bleeding?

Answer 8

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

Question 9

What is the managment of a minor bleed in a patient on warfarin if the INR is 5-8?

Answer 9

INR 5.0–8.0, minor bleeding
1. stop warfarin sodium
2. give phytomenadione (vitamin K1) by slow intravenous injection
3. restart warfarin sodium when INR < 5.0

Question 10

What is the management of an INR >8 withouth bleeding on warfarin?

Answer 10

1) stop warfarin sodium
2) give phytomenadione (vitamin K1) by mouth using the intravenous preparation orally [unlicensed use]
3) repeat dose of phytomenadione if INR still too high after 24 hours
4) restart warfarin when INR <5.0

Question 11

What is the guideline for an INR>8 on warfarin with a minor bleed?

Answer 11

INR >8.0, minor bleeding

1. stop warfarin sodium
2. give phytomenadione (vitamin K1) by slow intravenous injection
3. repeat dose of phytomenadione if INR still too high after 24 hours
4. restart warfarin sodium when INR <5.0