Warfarin Dosing Calculator

FAQs

What is warfarin?

Warfarin is one of the most common blood-thinning medications and is sold under the brand name Coumadin. It is taken orally. Warfarin prevents the formation of blood clots, lowering the chances of strokes. It is also used in the treatment of pulmonary thromboembolism or deep vein thrombosis. The most serious side effect of warfarin is bleeding. That's why it's crucial to know how to calculate warfarin dosing.

What are the warfarin monitoring rules?

Warfarin monitoring includes frequent INR checks — they are performed by a blood test, which requires a blood draw. A patient must undergo this procedure depending on their previous INR; this period usually ranges from 1 day to 4 weeks. 📅💡 There are other types of blood-thinning drugs called anticoagulants that do not require INR testing. These include: Injections with low-molecular-weight heparin (LMWH); Dabigatran (Pradaxa) taken orally; and Rivaroxaban (Xarelto) and apixaban (Eliquis), taken orally.

How do I read the INR warfarin chart?

In the table below, we gathered all the data used in our Coumadin dosing calculator in one place — let's make the process as easy as possible! Determine your patient's target INR and find the corresponding column in the table. In that column, find the patient's actual INR. Find the recommended dosage adjustments on the far right. Target INR 2-3Target INR 2.5-3.5Adjustments< 1.5< 2.0Consider increasing maintenance dose by 5–20%.Consider a single booster of 1.5–2× the daily maintenance dose.Schedule the next appointment in 3–7 days.1.5-1.72.0-2.3Consider increasing maintenance dose by 5–15%.Consider a single booster of 1.5–2× the daily maintenance dose.Schedule the next appointment in 3–7 days.1.8-1.92.3-2.4If the two previous INRs were in range, you might consider not making any adjustments to the dose.Consider increasing maintenance dose by 5–10%.Consider a single booster of 1.5–2× the daily maintenance dose.Schedule the next appointment in 3–7 days. 2.0-3.02.5-3.5Desired range.3.1-3.23.6-3.7If the two previous INRs were in range, you might consider not making any adjustments to the dose.Consider omitting one dose or decreasing maintenance dose by 5–10%.Schedule the next appointment in 3–7 days. 3.5-3.94.0-4.4Consider omitting one dose or decreasing maintenance dose by 5–15%.Schedule the next appointment in 1–3 days.>4.0>4.5Hold warfarin or decrease maintenance dose by 5–20%.Schedule the next appointment in 1 day.Always check your patient's compliance and look for any temporary changes that could affect their INR levels. Always consult ACCP & ASH guidelines when in doubt.

What to do in case of an increased INR?

The procedure in increased INR varies depending on the desired INR level, presence of bleeding, and the magnitude of the increase. According to INR adjustment charts, possible plans of action in a patient without serious bleeding may include: Omitting one dose; and Decreasing maintenance dose, by either 5–10%, 5–15% or 5–20%. We must always keep in mind the circumstances that may influence the INR levels, such as changes in diet, medications, or a patient's wellbeing (diarrhea, vomiting). Warfarin has multiple interactions with food and other drugs; the patient must be educated when initializing the treatment.

What to do in a case of a decreased INR?

The procedure in decreased INR varies depending on the desired INR level, presence of bleeding, and the magnitude of the decrease. According to INR adjustment charts, possible plans of action in a patient without serious bleeding may include: Administering single booster of 1.5–2× the daily maintenance dose; and Increasing maintenance dose, by either 5–10%, 5–15% or 5–20%. Always check for any changes in diet, drugs, general health of the patient. Check their compliance and inquire about any missed doses.