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. 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. 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. 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. 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.
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. 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. 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. 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
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