DOACs

Question 1

What are the common indications for direct oral anticoagulants?

Answer 1

1. Venous thromboembolism (VTE, collective term for DVT and PE): Treatment and prevention for the recurrence ( secondary prevention) of VTE.

or

Primary prevention of VTE in hip or knee surgery.

2. Atrial fibrillation
   Prevention of stroke and systemic embolism in non-valvular AF associated with at least one risk factor (including previous stroke, symptomatic heart failure, diabetes or hypertension.

Question 2

Give a brief mechanism of action

Answer 2

1. Works on the final part of coagulation cascade pathway
2. Directly inhibiting Factor Xa (10a)
3. Apixaban, edoxaban and rivaroxaban stops the conversion of prothrombin to thrombin
4. Dabigatran directly inhibits thrombin preventing the conversion of fibrogen to fibrin
5. All DOACs inhibit the formation of fibrin which:
   a. prevents clot formation
   or
   b. extentions within the vein and the heart

Question 3

State the important adverse effects for DOACs

Answer 3

BLEEDING
- Epistaxis: bleeding from the nose
- GI
- Genitourinary bleeding

Anaemia

GI upset

Dizziness

Elevated liver enzymes

Question 4

What is the benefit of a DOAC compared to warfarin?

Answer 4

The risk of:

Intercranial haemorrhage
and
Major bleeding

is less in DOACS

Question 5

Who should avoid DOACs?

Answer 5

People with:

Risk of major bleeding (peptic ulcers, cancers, recent surgeries)
Clinically significant bleeding

Question 6

True or FALSE? DOACs are excreted by multiple routes, including the CYP450 enzymes.

Answer 6

True

Question 7

What is the treatment dose of DVT and PE when using apixiban?

Answer 7

Treatment of deep-vein thrombosis,
Treatment of pulmonary embolism:

Initially 10 mg twice daily for 7 days, then maintenance 5 mg twice daily.

Question 8

What is the prophylaxis dose of DVT and PE when using apixiban?

Answer 8

Prophylaxis of recurrent deep-vein thrombosis,
Prophylaxis of recurrent pulmonary embolism

2.5 mg twice daily, following completion of 6 months anticoagulant treatment.

Question 9

What is the Prophylaxis of stroke and systemic embolism in non-valvular atrial fibrillation and at least one risk factor using apixiban?

Answer 9

Prophylaxis of stroke and systemic embolism in non-valvular atrial fibrillation and at least one risk factor (such as previous stroke or transient ischaemic attack, symptomatic heart failure, diabetes mellitus, hypertension, or age 75 years and over)

5 mg twice daily, alternatively 2.5 mg twice daily, reduced dose used in patients with at least two of the following characteristics: age 80 years and over, body-weight 60 kg or less, or serum creatinine 133 micromol/litre and over.