Warfarin Maintenance Dose Adjustments

ProfJameson Pharmacology Leave a comment  

Simple guidelines

Note: these are for maintenance doses only at steady state. Do NOT use these guidelines for starting someone on warfarin.

INR Dosage Adjustment
Less Than 1.3 Give them an extra dose and increase by 10% (always ask them if they “might” have missed a dose)
1.3 to 1.8 Increase weekly dose by 7 – 8% (always ask them if they “might” have missed a dose
1.8 – 2.0 Repeat the INR in one week, if still <2.0 than increase by 7%
2.0 t0 3.0 Smile
3.0 to 3.5 Check for patient errors in the dose first, then repeat the INR in 2 or 3 days. IF still elevated, decrease by 7% – 8%
3.5 to 4.5 Decrease by 7% – 8% (check for patient errors in the dose first)
Over 4.5 Hold the dose for one or two days and restart at a 10 – 20% lower weekly dose

Vitamin K

Often it is NOT necessary to give vitamin K. If you want to keep the patient anticoagulated, and you cannot stop yourself from giving vitamin K :-) … then give only 2.5 mg of phytonadione orally.

Do not give 10mg of vitamin K unless it is OK for the patient to NOT be anticoagulated for one or two weeks.

Obviously, you will usually give Vitamin K if the patient is bleeding.

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