What is the recommended initial dose of vitamin K (Vit K) for a patient with severe coagulopathy and bleeding?

Vitamin K Dosage for Severe Coagulopathy with Bleeding

For severe coagulopathy with active bleeding, administer 5-10 mg of intravenous vitamin K1 (phytonadione) immediately, co-administered with 4-factor prothrombin complex concentrate (PCC) at 25-50 U/kg based on INR level. 1

Critical First Principle: Vitamin K Alone is Insufficient

• Never rely on vitamin K alone for urgent reversal of severe bleeding, as it requires 12-24 hours to stimulate endogenous production of vitamin K-dependent clotting factors and will not provide immediate hemostasis 1, 2
• Vitamin K must be co-administered with immediate factor replacement (4-factor PCC) to achieve rapid reversal while ensuring sustained correction 1

Specific Vitamin K Dosing

• Administer 5-10 mg of intravenous vitamin K1 for warfarin-associated severe bleeding with coagulopathy 1
• The 5-10 mg dose range is specifically recommended because lower doses may not fully correct the INR, while doses exceeding 10 mg can prevent re-warfarinization for days and may create a prothrombotic state leading to further thromboembolism 1
• Intravenous administration is preferred over subcutaneous route in severe bleeding emergencies, though it must be given slowly (not exceeding 1 mg per minute) to minimize risk of anaphylactic reactions 3

Concurrent PCC Administration (Essential)

• Administer 4-factor PCC simultaneously with vitamin K using weight and INR-based dosing: 25 U/kg for INR 2-4.0,35 U/kg for INR 4-6.0, and 50 U/kg for INR >6.0 1
• PCC provides immediate replacement of factors II, VII, IX, and X, while vitamin K ensures sustained production after the 6-hour half-life of factor VII expires 1
• The combination prevents rebound INR elevation that can occur when PCC is given without vitamin K 1

Route of Administration Considerations

• Intravenous route is appropriate for severe bleeding emergencies despite the rare risk (3 per 100,000 doses) of anaphylactic reactions, which occur via a non-IgE mechanism possibly related to the solubilizer in the vitamin K solution 1
• Administer IV vitamin K slowly, not exceeding 1 mg per minute, to minimize anaphylaxis risk 3
• Oral vitamin K is preferred for non-emergent over-anticoagulation but is inadequate for severe active bleeding requiring immediate reversal 4, 5

Critical Anticoagulant-Specific Caveat

• Vitamin K is completely ineffective for direct oral anticoagulants (DOACs) including dabigatran, apixaban, rivaroxaban, edoxaban, or betrixaban 2
• For DOAC-associated severe bleeding, use specific reversal agents: idarucizumab 5 g IV for dabigatran, or andexanet alfa for factor Xa inhibitors 1, 2
• Only administer vitamin K if the patient is confirmed to be on warfarin or other vitamin K antagonists 2

Post-Administration Monitoring

• Monitor INR regularly over the next week, as a minority of patients require additional vitamin K due to prolonged warfarin clearance 1
• Recheck INR at 6-8 hours after administration; if not adequately shortened, repeat the dose 3
• Assess for hemostatic efficacy by monitoring hemoglobin, vital signs, and clinical bleeding cessation 1

Common Pitfalls to Avoid

• Do not give vitamin K without concurrent PCC in severe bleeding, as the 12-24 hour delay for vitamin K effect allows continued life-threatening hemorrhage 1, 2
• Do not exceed 10 mg of vitamin K, as higher doses create prolonged warfarin resistance and prothrombotic risk without additional benefit 1
• Do not use subcutaneous vitamin K in emergencies, as absorption is unreliable and slower than IV or oral routes 3, 4
• Do not assume all coagulopathy is warfarin-related; verify the anticoagulant type before administering vitamin K, as it is useless for DOACs 2