B-QuiCK: Oral anticoagulants

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B-QuiCK: Oral anticoagulant selection in primary care

Properties of oral anticoagulants used in primary care










(factor IIa)

Factor Xa

Vitamin K-dependent clotting (or coagulation) factors


12 – 14 hours

9 – 13 hours

8 – 11 hours

20 – 60 hours

Onset of action

2 hours

2.5 – 4 hours

3 hours


Key monitoring requirements

Renal function monitoring

(at least annually; more frequent if impaired at baseline)

INR monitoring

(regular and ongoing)

Funding status

Fully funded

Not funded

Fully funded

Tablet strengths available*

75 mg

110 mg

150 mg

10 mg

15 mg

20 mg

2.5 mg

5 mg

1 mg

2 mg

3 mg

5 mg

Usual dosing frequency

Twice day

(N.B. Once daily when used for VTE prophylaxis following surgery)

Once daily

Twice day

Once daily

Reversal agent



Unavailable in New Zealand

(options are available overseas)


(vitamin K, prothrombinex)

Key interactions

  • P-gp inhibitors (increases DOAC concentration)
  • P-gp inducers** (significantly decrease DOAC concentration)
  • Antacids
  • Strong CYP3A4 inhibitor + combined P-gp inhibitor, e.g. carbamazepine, rifampin, St John’s wort (significantly increase DOAC concentration)
  • Moderate CYP3A4 inhibitor + combined P-gp inhibitor, e.g. clarithromycin, diltiazem (moderately increase DOAC concentration)
  • Strong CYP3A4 inducer, e.g. phenytoin (significantly decrease DOAC concentration)
  • P-gp inducers** (significantly decrease DOAC concentration)
  • Numerous medicine interactions, e.g. erythromycin and other antibiotics, antifungals, amiodarone, NSAIDs; see NZF interaction checker for a comprehensive list
  • Food interactions; particularly vitamin K rich foods, e.g. avocados, broccoli, leafy green vegetables such as spinach


(see NZF for indication-specific dosing regimens)

All DOACs:

  • Prevention of stroke and systemic embolism in non-valvular atrial fibrillation
  • Treatment of deep-vein thrombosis and pulmonary embolism
  • Prevention of recurrent deep-vein thrombosis or pulmonary embolism
  • Prevention of venous thromboembolism following major joint surgery, e.g. hip, knee


  • Prevention and treatment of venous thrombosis and pulmonary embolism
  • Prevention of stroke following myocardial infarction in patients with increased embolic risk
  • Prevention of thromboembolism in patients with atrial fibrillation
  • Prevention of thromboembolism in patients with prosthetic heart valves

Additional indication for rivaroxaban only:

Prophylaxis of cardiovascular events in patients with coronary artery disease or peripheral artery disease (in combination with aspirin)

Contraindications or insufficient evidence to support use in primary care

(see NZF for cautions)

N.B. See Figure 1 in the full article for further information on use in patients with renal dysfunction

All oral anticoagulants:

  • Active serious bleeding
  • Certain bleeding-associated co-morbidities, e.g. severe thrombocytopenia or severe anaemia
  • History of recent high-risk bleeding event, e.g. intracranial haemorrhage (N.B. Patients with recent intracranial haemorrhage may still benefit from oral anticoagulant use, however, these decisions should be made in secondary care following neuroimaging)
  • Pregnancy (see: "Anticoagulation during pregnancy" section in the full article)

All DOACs:

  • Mechanical heart valves
  • Moderate-to-severe mitral stenosis
  • Severe liver disease


Usually avoided in primary care for patients with severe renal impairment but may be considered under secondary care guidance, if required


CrCl < 30 mL/min


CrCl < 15 mL/min


CrCl < 25 mL/min (N.B. Use may still be considered under secondary care guidance if CrCl 15 – 24 mL/min)

* As of November, 2023, two different warfarin brands are available in New Zealand. Coumadin is available in 1 mg, 2 mg and 5 mg strengths, and Marevan is available in 1 mg, 3 mg and 5 mg strengths. Avoid mixing brands to achieve appropriate dosing; they are not considered bioequivalent or interchangeable at any given tablet strength.

Examples of P-gp inhibitors include amiodarone, clarithromycin, cyclosporine, erythromycin, ivacaftor, ketoconazole, nifedipine, ticagrelor, tolvaptan, verapamil. Interaction increases DOAC concentration or effect.

** Examples of P-gp inducers include carbamazepine, phenytoin, rifampicin, St John’s wort. Interaction significantly decreases DOAC concentration or effect.

The distinction between relative and absolute contraindications for oral anticoagulant prescribing can be challenging as they are often context-specific and there are differing perspectives in the literature. The criteria listed here broadly encompass groups for whom oral anticoagulant initiation should be avoided in primary care; if there is any uncertainly, consult with secondary care.

CrCl = creatinine clearance; DOAC = direct oral anticoagulant; INR = international normalised ratio; P-gp = P-glycoprotein; VKA = vitamin K antagonist; VTE = venous thromboembolism

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