Enter the initial dosage and target INR, then divide by the current INR into the calculator to determine the adjusted dosage of Coumadin.

Coumadin Adjustment Formula

The following formula is used to calculate the adjusted dosage of Coumadin (Warfarin).

AD = (ID * INRt / INRc)

Variables:

  • AD is the adjusted dosage of Coumadin (mg)
  • ID is the initial dosage of Coumadin (mg)
  • INRt is the target INR (International Normalized Ratio)
  • INRc is the current INR

To calculate the adjusted dosage of Coumadin, multiply the initial dosage by the target INR, then divide the result by the current INR. The result is the adjusted dosage of Coumadin. Please note that this is a simplified formula and may not be suitable for all patients. Always consult with a healthcare professional before making any changes to medication dosages.

What is a Coumadin Adjustment?

A Coumadin adjustment refers to the process of altering the dosage of the medication Coumadin (also known as warfarin), which is an anticoagulant used to prevent blood clots. This adjustment is typically made based on the results of a patient's blood test, specifically the International Normalized Ratio (INR), which measures the time it takes for blood to clot. If the INR is too high, the patient is at risk of bleeding, and if it's too low, they are at risk of developing blood clots. Therefore, the dosage of Coumadin may need to be increased or decreased to maintain a safe and effective INR range.

How to Calculate Coumadin Adjustment?

The following steps outline how to calculate the Coumadin Adjustment.


  1. First, determine the initial dosage of Coumadin (ID) in milligrams (mg).
  2. Next, determine the target INR (INRt).
  3. Next, determine the current INR (INRc).
  4. Next, use the formula AD = (ID * INRt / INRc) to calculate the adjusted dosage of Coumadin (AD) in milligrams (mg).
  5. Finally, calculate the Coumadin Adjustment.
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Initial dosage of Coumadin (ID) = 5 mg

Target INR (INRt) = 2.5

Current INR (INRc) = 3.2