Vitamin K (FETT)

PHYTOMENADION

• Synonyms

  • Vitamin K1 (phytomenadione, phytonadione, or phylloquinone)

  • Vitamin K2 (menaquinone)

• Substance class: naphthoquinones

• Chemical structure:

  • Vitamin K1

  • Vitamin K2

• Inactive precursors (provitamins): none

• Active form: vitamin K hydroquinone

  • Activation occurs via enzyme epoxide reductase.

  • Mutations in the VKORC1 (Vitamin K epOxide Reductase Complex subunit 1) gene impair the reduction of vitamin K epoxide, resulting in deficiencies in vitamin K-dependent clotting factors.

• Sources

  • Leafy green vegetables (vitamin K1)

  • Eggs, dairy, and meat (vitamin K2)

  • Synthesized in small amounts by intestinal bacteria

• Transport: via lipoproteins; no specific protein

• Storage: liver

• Excretion: bile and urine

• Cofactor for γ-carboxylation of glutamate residues on vitamin-K-dependent proteins involved in:

  • Coagulation: maturation of factors II (prothrombin), VII, IX, and X, protein C, protein S

  • Bone formation: osteocalcin (bone Gla protein), matrix Gla protein

• Hypoprothrombinemia

• Vit. K deficiendy bleeding neonates

• Dietary requirements

Known hypersensitivity to phytonadione or any ingredient in the formulation.

Parenteral Administration: Pain, swelling, and tenderness at the injection site, transient “flushing sensations,” “peculiar” sensations of taste (dysgeusia). 

• Same activity as naturally occurring vitamin K1, which is required for the synthesis of blood coagulation factors II (prothrombin), VII (proconvertin), IX (Christmas factor or plasma thromboplastin component), and X (Stuart-Prower factor) in the liver. 

• Involved in carboxylation of the preformed, inactive precursors of these coagulation factors, resulting γ-carboxyglutamyl residues are required for the calcium-dependent phospholipid binding exhibited by active vitamin K-dependent clotting factors.

• Reverses the inhibitory effect of coumarin and indandione derivatives on the synthesis of these factors.