Name: Vitamin K
Class:
Mechanism: Cofactor in hepatic carboxylation of procoagulants—factors II, VII, IX, and X.
Absorption:
Dist.:
Metabolism.:
Excretion, t½:
Toxicity/S.E.s:
Utility: Antagonize coumarin anticoagulation (min. dose = 60-100 x RDA). Infants given injxn (infant GI tract lacks microbes that produce vitamin K).
Special Features: Deficiency ® bleeding diathesis. Some antibiotics kill gut microbes that synthesize vitamin K. Bishydroxycoumarin antagonizes effects of vitamin K. Prolonged use of large dose salicylates block vitamin K actions in prothrombin synth. ® hypoprothrombinemia.