Oral anticoagulants

Developed in collaboration with CASA Medical.

This clinical practice guideline is focussed on warfarin and the Direct-acting Oral Anti Coagulants (DOACs). This CPG does not apply to injected anticoagulants such as heparin products.  

Warfarin (Coumardin, Marevan) is a medication that acts on the Vitamin K pathways for clotting. DOACs are a newer class of oral medications that act on other blood clotting pathways. They are used as an anticoagulant for the treatment and prevention of venous thromboembolic (VTE) disease. 

DOACs are commonly used in DVT, PE, non-valvular atrial fibrillation (AF) and other conditions associated with increased risk of blood clots. Warfarin is still used in valvular AF, patients with impaired renal function, and in situations where DOACs are ineffective or otherwise can’t be used.  

Due to significant interactions with both diet and other drugs, warfarin requires frequent monitoring using the international normalised ratio (INR) to ensure that it remains within its therapeutic range. There is no routinely available testing for DOAC effectiveness, so if compliance is measured it is by monitoring dispensing or GP records. 

As warfarin and DOACs have increased risk of bleeding and the conditions being treated are of aeromedical significance, all pilots requiring anticoagulation needed to be assessed by the regulator. 

Warfarin and Novel Oral Anticoagulants (NOACs) may be approved for use by pilots and controllers, subject to assessment of the underlying medical condition. Holders of Class 1 and Class 3 medical certificates using anticoagulation medication will be subject to multi-crew and/or proximity restrictions. The issue of a Class 2 medical certificate without safety pilot restriction may be approved subject to assessment of underlying medical condition.   

Pilots or controllers considering point of care INR testing for warfarin treatment must:

• receive training and education in operating the monitor and managing warfarin dosing.
• Use a device approved by the appropriate medical regulatory authority, and
• Verify the accuracy of readings with the standard laboratory testing every 3 months.

Pilot and controller information

Stop flying or operating and inform your ME if:

• On commencement of anticoagulant treatment
• Any bleeding complications of treatment (significant bruising, nosebleeds, blood in any body fluids)
• Symptomatic recurrence of the condition being treated
• If on warfarin INR is outside the safe range (≥ 1.8 and ≤ 3.5)
• If a point of care device records a reading outside the safety range, this needs to be verified with formal laboratory INR
• Commencement of other medications that may interfere with anticoagulant activity.

For more information, see Medical Manual: Oral anticoagulants.