1. Dosing Nomograms for Initiation of Warfarin
2. Dosing Adjustment Nomogram for Maintenance Therapy
3. Patient Assessment Nomogram (pdf file)
4. Frequency of Monitoring

I. Dosing Nomograms for Initiation of Warfarin

• Flexible Initiation Method
  • This nomogram is useful in hospitalized patients in whom INR can be checked on a daily basis.
  • Several studies have confirmed that 5mg initiation achieves therapeutic anticoagulation as rapidly as 10mg initiation but with a lower frequency of supra-therapeutic INRs.
  • The 10mg initiation nomogram should only be used in relatively young and healthy patients who are likely to be insensitive to warfarin, or in patients taking concurrent medications known to induce warfarin metabolism .
  • Please note that loading doses of warfarin are NOT RECOMMENDED.

		5mg INITIATION	10mg INITIATION
Day	INR	DOSE	DOSE
1	–	5mg	10mg
2	< 1.5	5mg	7.5mg - 10mg
	1.5-1.9	2.5mg	2.5mg
	2.0-2.5	1.0 - 2.5mg	1.0 - 2.5mg
	> 2.5	0	0
3	< 1.5	5-10mg	5 - 10mg
	1.5-1.9	2.5 - 5mg	2.5 - 5mg
	2.0-2.5	0 - 2.5mg	0 - 2.5mg
	2.5-3.0	0 - 2.5mg	0 - 2.5mg
	> 3.0	0	0
4	< 1.5	10mg	10mg
	1.5-1.9	5 - 7.5mg	5 - 7.5mg
	2.0-3.0	0 - 5mg	0 - 5mg
	> 3.0	0	0
5	< 1.5	10mg	10mg
	1.5-1.9	7.5 - 10mg	7.5 - 10mg
	2.0-3.0	0 - 5mg	0 - 5mg
	> 3.0	0	0
6	< 1.5	7.5 - 12.5mg	7.5 - 12.5mg
	1.5-1.9	5 - 10mg	5 - 10mg
	2.0-3.0	0 - 7.5mg	0 - 7.5mg
	> 3.0	0	0

• Average Daily Dosing Method
  • This method for initiation of warfarin is particularly useful in ambulatory patients, and is specifically for patients with a goal INR of 2.0 – 3.0.

	Non-Sensitive Patients	Sensitive Patients*
Initial Dose	5mg qd	2.5mg qd
First INR	3 days	3 days
< 1.5	7.5mg qd	5mg qd
1.5 - 1.9	5mg qd	2.5mg qd
2-3	2.5mg qd	1.25mg qd
3.1-4	1.25mg qd	0.5mg qd
>4	hold	hold
Next INR	2 - 3 days	2 - 3 days
Subsequent dosing and monitoring	Continue dose escalation and frequent monitoring until lower limit of therapeutic range is reached.

* See factors that influence sensitivity to warfarin (below)

*Factors that influence sensitivity to warfarin include:

• age > 75
• clinical congestive heart failure
• diarrhea
• drug interactions (e.g. concurrent drugs that inhibit warfarin metabolism)
• elevated baseline INR
• fever
• hyperthyroidism
• malignancy
• malnutrition or NPO > 3 days

II. Dosing Adjustment Nomogram for Maintenance Therapy

GOAL INR 2.0 - 3.0		GOAL INR 2.5 - 3.5
< 2.0	• reload x 0-1 • increase by 5-15%	< 2.5
2.0 - 3.0	• no change	2.5 - 3.5
3.1 - 3.5	• decrease by 0-15%	3.6 - 4.0
3.6 - 4.0	• hold 0-1 dose • decrease by 5-15%	4.1 - 4.5
> 4.0	• hold until therapeutic • +/- minidose vitamin K • decrease by 10-20%	> 4.5

III. Patient Assessment Nomogram (pdf file)

IV. Frequency of Monitoring

• Initiation Therapy
  • Flexible initiation method: Daily through day 4, then within 3-5 days.
  • Average daily dosing method: Within 3-5 days until INR > lower limit of therapeutic range, then within 1 week .
  • After hospital discharge:
    • If stable: Within 3-5 days.
    • If unstable: Within 1-3 days.
  • First month of therapy: At least weekly.
• Maintenance Therapy
  • Dose held today in patient with significant over anticoagulation:
    In 1 - 2 days.
  • Dosage change today: Within 1 - 2 weeks.
  • Dosage change < 2 weeks ago: Within 2 - 4 weeks.
  • Routine follow-up of medically stable & reliable patients: Every 4 - 6 weeks.
  • Routine follow-up of medically unstable or unreliable patients: Every 1 - 2 weeks.