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Protocol for warfarin administration and adjustment to maintain INR between 2 and 3 for pediatric patients

Protocol for warfarin administration and adjustment to maintain INR between 2 and 3 for pediatric patients
  1. Day 1 – If the baseline INR is 1.0 to 1.3, initial dose of warfarin is 0.2 mg/kg orally in a single dose*
  1. Days 2 to 4 – Adjust warfarin dose according to INR:
INR 1.1 to 1.3 Give same dose as on day 1
INR 1.4 to 3.0 Give 50% of day 1 dose
INR 3.1 to 3.5 Give 25% of day 1 dose
INR >3.5 Hold warfarin until INR <3.5, then restart at 50% reduced dose
  1. Maintenance dose – Adjust warfarin dose according to INR:
INR 1.1 to 1.4 Increase dose by 20%
INR 1.5 to 1.9 Increase dose by 10%
INR 2.0 to 3.0 No change
INR 3.1 to 3.5 Decrease dose by 10%
INR >3.5 Hold warfarin until INR <3.5, then restart at 20% reduced dose
INR: international normalized ratio.
* In patients with mild liver dysfunction and/or elevated baseline prothrombin time, a lower initial dose should be used (eg, 0.1 mg/kg). Warfarin should be avoided in patients with severe liver failure.
References:
  1. Monagle P, Chan AK, Goldenberg NA, et al. Antithrombotic therapy in neonates and children: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest 2012; 141:e737S.
  2. Trucco M, Lehmann CU, Mollenkopf N, et al. Retrospective cohort study comparing activated partial thromboplastin time versus anti-factor Xa activity nomograms for therapeutic unfractionated heparin monitoring in pediatrics. J Thromb Haemost 2015; 13:788.
Original table modified for this publication. From: Michelson AD, Bovill E, Andrew M. Antithrombotic therapy in Children. Chest 1995; 108:506S. Table used with the permission of Elsevier, Inc. All rights reserved.
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