Warfarin Dosing Calculator – Warfarin Dosage Calculation App

A Warfarin Dosing Calculator is a specialized tool used by healthcare professionals to determine the appropriate dosage of warfarin for patients.

The calculator takes into account several factors, including:

• Patient’s current INR (International Normalized Ratio)
• Target INR range
• Current warfarin dose
• Patient-specific factors (age, weight, medical history)

For example, consider a patient with atrial fibrillation:

Current INR: 1.8

Target INR range: 2.0-3.0

Current warfarin dose: 5mg daily

Warfarin is an anticoagulant medication used to prevent blood clots in various conditions such as atrial fibrillation, deep vein thrombosis, and pulmonary embolism.

Warfarin Dosing Calculator

Current Weekly Dose	Current INR	Target INR	New Weekly Dose	Conversion Equation
35mg	1.8	2.5	41.7mg	35 × (1.8 / 2.5)^(-1.5)
40mg	3.2	2.5	35.4mg	40 × (3.2 / 2.5)^(-1.5)
28mg	1.6	2.0	32.1mg	28 × (1.6 / 2.0)^(-1.5)
50mg	3.8	3.0	42.6mg	50 × (3.8 / 3.0)^(-1.5)
45mg	2.7	2.5	43.3mg	45 × (2.7 / 2.5)^(-1.5)

Warfarin Dosing Formula

The Warfarin Dosing Formula is based on the relationship between INR changes and dose adjustments.

New Weekly Dose = Current Weekly Dose × (Current INR / Target INR)^(-1.5)

Example:

• Current weekly dose: 35mg (5mg daily)
• Current INR: 1.8
• Target INR: 2.5

New Weekly Dose = 35 × (1.8 / 2.5)^(-1.5) ≈ 41.7mg

This suggests increasing the weekly dose to approximately 42mg, or 6mg daily.

How do I adjust my INR dosing?

General guidelines include:

1. Small adjustments: Typically 5-20% of the total weekly dose
2. Frequency: Check INR 4-7 days after dose changes
3. Consistency: Maintain consistent dietary vitamin K intake

Remember, never adjust your warfarin dose without consulting your healthcare provider.

Warfarin Dosage Chart

INR Range	Dose Adjustment
< 1.5	Increase by 15-20%
1.5-1.9	Increase by 5-10%
2.0-3.0	No change (if within target)
3.1-3.9	Decrease by 5-10%
4.0-4.9	Hold 1-2 doses, then decrease by 10-15%
≥ 5.0	Hold dose, consider vitamin K, recheck INR

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