GlobalRph

This calculator should be used for informational purposes
  only and not for direct  patient care.
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Coumadin Dosing 
This program works best when used on the first day of therapy
Based on a modified version of the Fennerty nomogram.  Nomogram targets INR of 2-3. 
Limit initial dose to 5 mg for patient's over 65 or patients who
 are receiving potentially interacting drugs.

Note: This program no longer reflects the standard of practice concerning warfarin therapy. Lower initial starting doses are recommended in most patients regardless of age. For additional information please review the latest anticoagulation guidelines available in the journal "Chest."   ["SIXTH ACCP CONSENSUS CONFERENCE ON ANTITHROMBOTIC THERAPY."]
Select age group
Enter day of therapy:
Enter patients INR:
Useful Links:
1)  Fennerty nomogram
2)  U of M guidelines   also here
3)  Initial dosing?
4)  Management of anticoagulation
5)  Warfarin therapy
6)  AAFP
7)  Warfarin Info by Al Lodwick 

INDICATION1

 INR RANGE

Prophylaxis of venous thrombosis (high-risk surgery)
Treatment of venous thrombosis
Treatment of PE
Prevention of systemic embolism
Tissue heart valves
AMI (to prevent systemic embolism)*
Valvular heart disease
Atrial fibrillation

 2.0 to 3.0
Mechanical prosthetic valves (high risk) 2.5 to 3.5
Bileaflet mechanical valve in aortic position 2.0 to 3.0
Certain patients with thrombosis and the antiphospholipid syndrome > 2.0 to 3.0
*If oral anticoagulant therapy is elected to prevent recurrent MI, an INR of 2.5 to 3.5 is recommended, consistent with Food and Drug Administration recommendations.
Managing oral anticoagulant therapy --ACCP recommendations

1.  Jack Ansell, Jack Hirsh, James Dalen, Henry Bussey, David Anderson, Leon Poller, Alan Jacobson, Daniel Deykin, and David Matchar. Managing Oral Anticoagulant Therapy.  Chest 2001 119: 22S-38S.
 "SIXTH ACCP CONSENSUS CONFERENCE ON ANTITHROMBOTIC THERAPY."

 

Fennerty nomogram: designed to rapidly achieve a target  INR of 2 to 3 while reducing the risk of overanticoagulation which is more likely to occur in patients who exhibit greater sensitivity to warfarin (elderly patients, patients with liver disease, inadequate nutrition, or CHF).
Day INR Warfarin dose (mg) given at 5 pm
     
1st < 1.4 10
     
2nd < 1.8 10
  1.8 1.0
  > 1.8 0.5
     
3rd <2.0 10
  2.0-2.1 5
  2.2-2.3 4.5
  2.4-2.5 4
  2.6-2.7 3.5
  2.8-2.9 3
  3.0-3.1 2.5
  3.2-3.3 2
  3.4 1.5
  3.5 1.0
  3.6-4.0 0.5
  >4.0 0
     
    Predicted maintenance dose:
4th <1.4 >8
  1.4 8
  1.5 7.5
  1.6-1.7 7
  1.8 6.5
  1.9 6
  2.0-2.1 5.5
  2.2-2.3 5
  2.4-2.6 4.5
  2.7-3.0 4
  3.1-3.5 3.5
  3.6-4.0 3
  4.1-4.5 Miss out next day's dose,  then give 2 mg
  >4.5 Miss out 2 days' doses then give 1 mg
Fennerty A, Thomas P, Backhouse G, Bentley DP, Campbell IA, Routledge PA.  Flexible induction dose regimen for warfarin and prediction of maintenance dose.  Br Med J 1984; 288:1268-70.