Understanding Persistent Therapeutic INR After Vitamin K Administration

Pharmacokinetic Differences Between Routes

• The American College of Cardiology suggests that oral vitamin K produces a more gradual, sustained effect that can keep INR in therapeutic range for 24-48 hours or longer 1
• After oral administration of 1-2.5 mg, 95% of patients show INR reduction within 24 hours, with 85% achieving INR <4.0, but only 35% reaching INR ≤1.9 1
• When warfarin is simply stopped without vitamin K, INR falls from 2.0-3.0 to normal range over 4-5 days 1
• High-dose vitamin K (5-10 mg) can cause warfarin resistance for up to a week, regardless of route 1, 2
• The dose of 5 mg is appropriate for INR >5.0, but route dramatically affects the reversal pattern 1, 3