Pharm 101: Vitamin K



  • Confers biologic activity upon factors II (prothrombin), VII, IX and X by participating in their postribosomal modification
  • Two forms:
    • Vitamin K1 is found in food, primarily green leafy vegetables
    • Vitamin K2 synthesised by intestinal bacteria
  • Clinical uses:
    • Reversal of warfarin anticoagulation, prevention of haemorrhagic disease of new born
    • IV or PO Vitamin K1 is available clinically
    • IV administration should be slow as rapid infusion can cause dyspnoea, chest and back pain, and death
Reversal of warfarin anticoagulation
  • Warfarin prevents reductive metabolism of inactive vitamin K to active form so produces biologically inactive VII, IX, X, prothrombin, protein C and S
  • Vitamin K confers biologic activity upon factors II, VII, IX, X by participating in their postribosomal modification
  • Re-establishes normal activity of vitamin K dependent clotting factors II, VII, IX, X
  • 6-24 hours for effect
Further reading
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MBBS CCPU (RCE, Biliary, DVT, E-FAST, AAA) Rob is an Emergency Medicine Advanced Trainee based in Melbourne, Australia. He has special interests in medical education, ECG interpretation, and the use of diagnostic and procedural ultrasound in the undifferentiated and unwell patient.

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