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Overview :
The availability of vitamin K is affected by a variety of
dietary and drug-related factors.
Vitamin K is fat-soluble and light sensitive (which may
reduce levels in unshielded TPN solutions).
Factors interfering with vitamin K absorption:
(1) pica
(2) ingestion of mineral oil
(3) cholestyramine
(4) large oral doses of vitamin A
Factors interfering with enteric production of vitamin K by
bacteria:
(1) antibiotics
Factors interfering with vitamin K metabolism
(antagonists):
(1) therapy with coumarin/warfarin
(2) coumarin-like compounds in herbal medications or
plants
(3) aspirin in large doses
(4) phenytoin
(5) large doses of vitamin E
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