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Warfarin Maintenance Dosing Adjustment Nomogram for INR Goal of 2-3
Adjustment Guidelines

  • A: Baseline CBC, PT/INR required prior to continuation of warfarin therapy.
  • B: Assess patient compliance and determine if any changes have been made that may impact therapy: 1) addition of interacting drugs or herbal products; 2) changes in diet (eating/not eating) 3) changes in health status.
  • C: Based on the INR results make adjustments to the current therapy based on the ranges below:
Adjustment Guidelines   Printable version
INR < 1.5
1. ] Verify compliance (if non-compliant: resume therapy at previous dose).
2. ] If dosage adjustment needed: increase maintenance dose by 5%- 20%*.

[* Some clinicians recommend a ‘booster dose’ 1.5 to 2x the daily maintenance dose x 1 ]

3. ] Return: 3 – 7 days
INR 1.5 – 1.9
1. ] Verify compliance (if non-compliant: resume therapy at previous dose).
2. ] [* Some clinicians recommend a ‘booster dose’ 1.5 to 2x the daily maintenance dose x 1 ]
3. ] If dosage adjustment needed: increase maintenance dose by 5 – 15% (use lower end of this range for INR values close to the therapeutic range).
4. ] Return: 3 – 7 days
INR 2.0 – 3.0
1. ] No Changes Needed
2. ] Return: 4 weeks
INR 3.1 – 3.4
1. ] Dose adjustment usually not necessary if level is at the low end of this range ( 3.1 – 3.2) and at least two previous levels were therapeutic. Recheck in 3 to 7 days.
2. ] Consider decreasing dose by 5 – 10% and/or holding one dose.
3. ] Recheck in 3- 7 days.
INR 3.5 – 3.9
1. ] consider holding one dose.
2. ] evaluate any clinical changes that may have occurred with the patient (eating regularly, no new medications, etc.)
3. ] consider decreasing the maintenance dose by 5 -15% depending on magnitude of the INR elevation.
4. ] Return: 1- 3 days.
INR 4.0 – 4.9 with no significant bleeding
1. ] Hold warfarin until INR is within the therapeutic range.
2. ] Recommend lowering maintenance dose by 5%- 20%
3. ] Increase frequency of monitoring until problem resolved (daily initially).
4. ]  (8th ACCP)1:  If only minimally above therapeutic range or associated with a transient causative factor, no dose reduction may be required.
INR > 5.0
1. ] See 8th ACCP guidelines.1
2. ] Return: daily

Warfarin related Links

References:

1. Ansell J, Hirsh J, Hylek E, Jacobson A, et al. Pharmacology and Management of the Vitamin K Antagonists: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest. 2008 (suppl 6);133:160s-198s.
Warfarin Maintenance Dosing Adjustment Nomogram