Vitamin k


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Vitamin k

  1. 1. Sathish kumar.R Altheanz 09
  2. 2.  It is a fat soluble dietary principle required for the synthesis of clotting factors. Chemistry ◦ Vitamin k has a naphthoquinone ring and a side chain(R).
  3. 3.  Based on the alkyl (R)group vitamin k may be classified as K1 – (R-phytyl) phytonadione phylloquinone K2 – (R-prenyl) menaquinone K3 – no side chain menadione acetamenaphthone
  4. 4. DIETARY SOURCE • Green leafy vegetables such as cabbage, spinach and liver, cheese,etc… RDA  It is uncertain because colonic bacteria itself produces a variable amount of menaquinone ( vit k2)  However the total requirement for an adult has been estimated to be 50-100 µg/day
  5. 5. UTILIZATION  Water soluble vitamin absorb directly into portal blood.  Fat soluble vitamins Absorbed from intestine via lymph ( requires bile salts for absorption) Temporarily stored in liver Metabolized by side chain cleavage, glucuronide conjugation Metabolites are excreted in bile & urine
  6. 6.  Vitamin K has a main role in coagulation  It acts as a cofactor in late stage of synthesis of coagulation proteins ( prothrombin, factors vii,ix,x) which are synthesized by liver as inactive zymogens.
  7. 7. Vit K dependent carboxylase Warfarin Dicoumarol Gamma carboxy glutamic acid Get bound to phospholipid surfaces Participate in coagulation cascade
  8. 8.  Vitamin K to a certain extent aids in bone formation through gamma carboxylation of osteocalcin Binds tightly to hydroxy apatite crystals of bone
  9. 9. Only use is in prophylaxis and treatment of bleeding due to deficiency of clotting factorsin following situations  DIETARY DEFICIENCY Rare but when it occurs 5–10 mg/day oral or parenteral vitamin K is administered  PROLONGED ANTIMICROBIAL THERAPHY  OBSTRUCTIVE JAUNDICE, MALABSORPTION SYNDROMES vit K 10mg i.m/day or orally along with bile salts.
  10. 10.  LIVER DISEASES (CIRRHOSIS, VIRAL HEPATITIS) Vit K may be of some use here  NEW BORNS • due to lower capacity to synthesise clotting factors • Vit K 1mg i.m soon after birth • Administered 5- 10 mg i.m to mother 4-12 hrs before delivery  PROLONGED HIGH DOSE SALICYLATE THERAPY CAUSING HYPOPROTHROMBINEMIA
  11. 11.  OVER DOSE OF ORAL ANTICOAGULANTS causing hypoprothrombinemia, bleeding Vitamin K1(phytonadione) is given. It is the drug of choice because it acts rapidly  If severe bleeding occurs • 10 mg i.m followed by 5mg 4 hourly • Bleeding stops in 6-12 hrs • But the normal levels of coagulation factors are restored only after 24 hrs
  12. 12. • Hemorrhagic disease of newborn • Bruising tendency • Echymotic patients • Mucous membrane haemorrhage • Post – traumatic bleeding • Internal bleeding(GIT, Nose) • Prolonged clotting,prothrombin time • haematuria
  13. 13.  Rapid i.v injection of emulsified vit K causes  Flushing  Breathlessness  Chest constriction  Fall in B.P  manifestations of toxicity are  Hemolysis  Hyperbilirubinemia-by competitive inhibition of glucuronidation  Kenicterus
  14. 14. Thank you