What is the maximum dose of Vitamin K (Vit K) for anticoagulant reversal?

Maximum Dose of Vitamin K for Anticoagulant Reversal

The maximum recommended dose of vitamin K is 10 mg, as doses exceeding 10 mg can create a prothrombotic state and prevent re-warfarinization for days. 1

Dosing Based on Clinical Scenario

Life-Threatening Bleeding

• Administer 10 mg IV vitamin K by slow infusion over 30 minutes plus 4-factor prothrombin complex concentrate (PCC). 1, 2, 3
• The 10 mg dose represents the upper limit because higher doses create warfarin resistance requiring heparin bridging if anticoagulation needs to be resumed. 1, 2, 3
• Always co-administer with PCC because vitamin K alone takes 4-24 hours to normalize coagulation, whereas PCC achieves INR <1.5 within 5-15 minutes. 1, 3

Major Bleeding (Non-Life-Threatening)

• Administer 5-10 mg IV vitamin K by slow infusion over 30 minutes. 1, 2
• The FDA-approved dosing for anticoagulant-induced prothrombin deficiency allows "up to 25 mg initially" with rare instances requiring 50 mg, but current guidelines strongly recommend against exceeding 10 mg due to complications. 1, 4

Elevated INR Without Bleeding

• For INR 4-10: Use 1-2.5 mg oral vitamin K. 1, 2, 5
• For INR >10: Use 3-5 mg oral vitamin K. 2, 5, 3
• These lower doses achieve INR <4.0 within 24 hours in 85% of patients without causing warfarin resistance. 5, 3

Critical Safety Considerations

Risk of Overcorrection

• More than 10 mg vitamin K prevents re-warfarinization for days and creates a prothrombotic state that can lead to thrombosis. 1
• The absolute risk of thromboembolism from overcorrection is in the same range as the risk of bleeding from over-anticoagulation. 6
• High-dose vitamin K (10 mg) creates warfarin resistance for up to one week, requiring heparin bridging if warfarin needs to be resumed. 2, 3

Anaphylactic Reactions

• IV vitamin K carries a risk of anaphylactic reactions in 3 per 100,000 doses via a non-IgE mechanism, potentially resulting in cardiac arrest. 1, 2, 3
• This reaction is possibly due to the solubilizer in the vitamin K solution rather than the vitamin K itself. 1
• Always administer IV vitamin K by slow infusion over 30 minutes, not exceeding 1 mg per minute. 4

Route-Specific Considerations

Intravenous Administration

• Preferred for emergent reversal, achieving INR reduction in 4-6 hours. 1
• Must be given slowly over 15-30 minutes in 25-50 mL normal saline. 1
• Maximum infusion rate is 1 mg per minute per FDA labeling. 4

Oral Administration

• Preferred for non-emergency situations, achieving INR reduction in 18-24 hours. 1
• More predictable and safer than subcutaneous route, which has unpredictable absorption and is not recommended. 1
• Low doses (1-2.5 mg) are sufficient for INR 4-10 without bleeding. 1, 5, 7

Common Pitfalls to Avoid

• Never administer high-dose vitamin K (>10 mg) unnecessarily, as it leads to prolonged warfarin resistance and potential thrombotic complications. 1, 2, 5
• Do not use vitamin K alone for life-threatening bleeding—it must be combined with PCC because factor VII in PCC has only a 6-hour half-life. 2, 3
• Avoid subcutaneous administration due to unpredictable absorption and risk of cutaneous reactions. 1, 6
• Do not exceed 1 mg per minute infusion rate when giving IV vitamin K to minimize anaphylactic risk. 4