Suggested protocol for initiating warfarin therapy

Days of warfarin treatment	INR <1.5	INR 1.5 to 1.9	INR 2.0 to 3.0	INR >3.0
Suggested initial dose for days 1 and 2
Normal adult	5 mg*	n/a	n/a	n/a
Frail adult, malnourished, elderly, liver disease	2.5 mg*	n/a	n/a	n/a
Dosing for day 3 and beyond
Day 3	5 to 10 mg	2.5 to 5 mg	0 to 2.5 mg	No dose
Day 4	10 mg	5 to 7.5 mg	0 to 5 mg	No dose
Day 5	10 mg	7.5 to 10 mg	0 to 5 mg	No dose
Day 6	7.5 to 12.5 mg	5 to 10 mg	0 to 7.5 mg	No dose

In this protocol, which is provided for guidance only, suggested doses of warfarin after day 2 are given as ranges. The clinician must judge the rapidity and magnitude of INR changes for the individual patient and make dosage adjustments accordingly. An algorithm for monitoring and adjustment of maintenance warfarin is presented separately. Refer to UpToDate topics on use of warfarin and table on suggested protocol for adjustment of maintenance warfarin.

n/a: not applicable.
* This table assumes that the patient has started with an INR in the normal range.

Refer to text for details concerning the source for this protocol and relevant references.

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