Warfarin Maintenance Dosing Adjustment Nomogram

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.