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Anticoagulation - oral - Management
What maintenance regimen of warfarin is recommended?

  • The maintenance dose of warfarin depends on the international normalized ratio (INR) during monitoring.
  • A target INR of 2.5 is recommended for:
    • Deep vein thrombosis.
    • Pulmonary embolism (including those associated with antiphospholipid syndrome or for recurrence in people no longer receiving warfarin).
    • Atrial fibrillation.
    • Cardioversion (higher target values, such as an INR of 3, can be used for up to 4 weeks before the procedure to avoid cancellations due to low INR).
    • Dilated cardiomyopathy.
    • Mural thrombus.
    • Symptomatic inherited thrombophilia.
    • Coronary artery thrombosis (if anticoagulated).
    • Paroxysmal nocturnal haemoglobinuria.
  • A target INR of 3.5 is recommended for:
    • Recurrent deep-vein thrombosis.
    • Pulmonary embolism in people currently receiving warfarin with INR above 2.
  • Mechanical prosthetic heart valves:
    • The recommended target INR depends on the type and location of the valve. A target INR of 3 is usually recommended for mechanical aortic valves, and 3.5 for mechanical mitral valves.
  • Some people may be confused and have difficulty complying with treatment (for example, those with impaired cognition). If there are concerns about this, consider the use of support services (such as district nurse or health visitor), dosette compliance aids (for example, Medidose®, or Manerex®), or both. In the absence of such facilities, the risk of using warfarin may outweigh the benefits.
  • The healthcare professional who monitors the INR and warfarin dosing for people who use compliance aids should inform the dispensing pharmacist of the warfarin dosage directions after each patient consultation. In general it is recommended that the prescription should:
    • Use the fewest number of tablets each day.
    • Use constant daily dosing (not alternate-day dosing).
    • Avoid the use of half tablets — people find it difficult to break tablets in half and would rather use 0.5 mg tablets.

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