Drug Groups

approved

Description

Phytonadione is often called vitamin K1. It is a fat-soluble vitamin that is stable to air and moisture but decomposes in sunlight. It is found naturally in a wide variety of green plants. Phylloquinone is also an antidote for coumatetralyl. Vitamin K is needed for the posttranslational modification of certain proteins, mostly required for blood coagulation.

Indication

For the treatment of haemorrhagic conditions in infants, antidote for coumarin anticoagulants in hypoprothrombinaemia

Pharmacology

Phytonadione is a vitamin, indicated in the treatment of coagulation disorders which are due to faulty formation of factors II, VII, IX and X when caused by vitamin K deficiency or interference with vitamin K activity. Phytonadione aqueous colloidal solution of vitamin K1 for parenteral injection, possesses the same type and degree of activity as does naturally-occurring vitamin K, which is necessary for the production via the liver of active prothrombin (factor II), proconvertin (factor VII), plasma thromboplastin component (factor IX), and Stuart factor (factor X).

Toxicity

The intravenous LD₅₀ of phytonadione in the mouse is 41.5 and 52 mL/kg for the 0.2% and 1% concentrations, respectively.

Affected Organisms

Absorption

Oral phytonadione is adequately absorbed from the gastrointestinal tract only if bile salts are present. After absorption, phytonadione is initially concentrated in the liver, but the concentration declines rapidly. Very little vitamin K accumulates in tissues.

Elimination

Almost no free unmetabolized vitamin K appears in bile or urine.

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