Warfarin Dosing Protocol Calculator
Adjust weekly Warfarin dosages based on INR readings. Provides calculated percentage adjustments and pill combination suggestions.
About
Warfarin therapy requires strict monitoring of the International Normalized Ratio (INR) to prevent thrombosis (low INR) or hemorrhage (high INR). This calculator aids clinicians and pharmacists in adjusting the total weekly dose based on current INR relative to the target range (typically 2.0-3.0). It uses standard anticoagulation guidelines to recommend percentage-based dose increases or decreases. The tool also simplifies the complexity of pill management by suggesting how to distribute the new weekly total using common tablet strengths (e.g., 5mg), ensuring patient adherence.
Formulas
Dose adjustments are calculated on a weekly total basis:
Example: For an INR of 1.4, increasing a 30mg weekly dose by 15%:
Reference Data
| INR Reading | Dose Adjustment | Action |
|---|---|---|
| < 1.5 | Increase 10-20% | Consider extra dose. Retest in 1 week. |
| 1.5 - 1.9 | Increase 5-10% | Retest in 1-2 weeks. |
| 2.0 - 3.0 | No Change | Therapeutic Range. Retest in 4 weeks. |
| 3.1 - 3.9 | Decrease 5-10% | Retest in 1-2 weeks. |
| 4.0 - 4.9 | Decrease 10-20% | Hold 1 dose? Retest in 1 week. |
| ≥ 5.0 | Hold & Seek Advice | Urgent medical review required. Vitamin K may be needed. |