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.