Vitamins

Vitamin K

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Vitamin K, Vitamin K1, Phylloquinone, Phytomenadione, Phytonadione, Vitamin K2, Menaquinone, Vitamin K3, Menadione

  • Background
  1. Vitamin K is a fat soluble Vitamin synthesized in plants (esp. green leafy vegetables)
  2. Three forms of Vitamin K
    1. Vitamin K1 (Phytomenadione, from plant sources)
      1. Primary source of ingested Vitamin K in humans
    2. Vitamin K2 (Menaquinone, from Bacteria, including intestinal Bacteria in humans)
    3. Vitamin K3 (Menadione, synthetic Vitamin K)
  3. Sources
    1. Green leafy vegetables
    2. Liver
    3. Cheese
    4. Butter
    5. Egg yolk
  • Physiology
  1. Vitamin K is required for Coagulation Factors 2,7, 9, 10 and Protein C and Protein S
  2. Vitamin K Deficiency may result in Bleeding Disorders
    1. Hemorrhagic Disease of the Newborn
  3. Vitamin K Toxicity or Overdose may result in Hemolytic Anemia or Kernicterus
  4. Warfarin (Coumadin) is a Vitamin K mimic that functions as a Competitive Antagonist to Vitamin K epoxide reductase
    1. Results in Vitamin K Deficiency
  • Indication
  1. Reversal of excessive Anticoagulation with Coumadin
  • Dosing (See Coumadin Protocol)
  1. Routes: IV, IM, SQ, PO
    1. Oral route is preferred in most cases (consistently absorbed with excellent efficacy)
    2. IV route is indicated in life threatening bleeding or intolerance to oral administration
      1. IV route risks anaphylactic reaction (esp. rapid infusion)
    3. Intramuscular Injection (of any medication) is not recommended with supratherapeutic INR
      1. Risk of Muscle and extremity injury due to localized bleeding
    4. Subcutaneous administration is not recommended due to unpredictable absorption
  2. INR 4 to 10
    1. Give Vitamin K 1-2 mg orally
    2. Dilute parenteral Vitamin K 1-2 mg in flavored drink
    3. Administer Vitamin K 0.5-1 mg IV if not able orally
  3. INR over 10 without bleeding complications
    1. Vitamin K 3 mg SC or slow IV infusion (over 15-30 min)
    2. Check INR at 6 hours
    3. Consider repeating Vitamin K at 6 hours if unchanged
  4. Serious bleeding complication at any elevated INR
    1. Replace Clotting Factors
      1. Vitamin K 10 mg SC or slow IV infusion
      2. Fresh Frozen Plasma (FFP) 15 ml/kg
      3. Prothrombin Complex Concentrate (PCC) 50 U/kg
    2. Check INR at 6 hours
  • Precautions
  1. Anticoagulant-laced Synthetic Cannabinoids
    1. Drugs contaminated with Brodifacoum rat poison
    2. May require Vitamin K doses as high as 50 mg orally tid for months
    3. Extortionary Vitamin K prices of $50 per 5 mg Vitamin K tab, may cost $45,000 per month
    4. (2018) Presc Lett 25(6):35 [PubMed]
  1. Consensus Conference (Dalen) advocates giving
    1. Vitamin K SC/IV for INR > 6
    2. Dalen (1995) Chest 108 (sppl):225S-522S (Consensus) [PubMed]
  2. Retrospective study of 51 Arizona Patients with INR >6
    1. No Vitamin K given in 48 patients, Coumadin stopped
    2. No adverse outcomes or major bleeding
    3. Glover (1995) Chest 108:987-90 [PubMed]
  3. Oral Vitamin K 1 mg acts faster than subcutaneous
    1. Crowther (2002) Ann Intern Med 137:251-4 [PubMed]