Vitamin K Administration for INR Reduction

Clinical Context and Dosage

• The American College of Cardiology recommends 5-10 mg IV vitamin K by slow infusion over 30 minutes for serious bleeding, and 10 mg IV vitamin K plus prothrombin complex concentrate (PCC) for life-threatening bleeding 1, 2
• For non-bleeding elevated INR, 1-2.5 mg oral vitamin K is expected to achieve INR <4.0 within 24 hours in 85% of patients, while 3-5 mg oral vitamin K is used for INR >10 without bleeding 1, 3, 4

Important Considerations

• High-dose vitamin K (10 mg) creates warfarin resistance for up to one week, requiring heparin bridging if warfarin needs to be resumed 1, 3
• Anaphylactic reactions occur in 3 per 100,000 IV vitamin K doses, and administration should be by slow infusion over 30 minutes 2
• Do not exceed 10 mg vitamin K, as higher doses create a prothrombotic state and prolong warfarin resistance 2

Mechanism and Efficacy

• Vitamin K alone is insufficient for emergent reversal, with PCC achieving INR <1.5 within 5-15 minutes, while vitamin K alone takes hours 2
• Always co-administer PCC with 10 mg vitamin K in life-threatening bleeding because factor VII in PCC has only a 6-hour half-life 2