Vitamin k
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Transcript of Vitamin k
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VITAMIN K
Sathish kumar.RAltheanz 09
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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).
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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 menadioneacetamenaphthone
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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
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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
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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.
PHYSIOLOGICAL ROLE
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Vit K dependent carboxylase
Warfarin Dicoumarol
Gamma carboxy glutamic acid
Get bound to phospholipid surfaces
Participate in coagulation cascade
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Vitamin K to a certain extent aids in bone formation through
gamma carboxylation of osteocalcin
Binds tightly to hydroxy apatite crystals of bone
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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.
USES
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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
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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
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• Hemorrhagic disease of newborn• Bruising tendency• Echymotic patients• Mucous membrane haemorrhage• Post – traumatic bleeding• Internal bleeding(GIT, Nose)• Prolonged clotting,prothrombin time• haematuria
DEFICIENCY MANIFESTATIONS
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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
ADVERSE EFFECTS
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Thank you