Effect of vitamin E on prothrombin levels in warfarin-induced vitamin K deficiency.
Rats rendered lightly vitamin K deficient with warfarin (0.01 mg/100 g, IP) and given the equivalent of 1000 units of vitamin E/kg IM for 7 days, showed a marked reduction in functional factor II activity, but normal factor II levels using Echis venom on coagulation analysis. In 12 humans receiving warfarin, vitamin E was administered in doses of 100 or 400 units/day orally for 4 wk. The results in these patients showed no significant change in the prothrombin time, factor II coagulant activity, or factor II antigen (by electroimmunoassay). However, by using a ratio of factor II coagulant activity to immunoreactive protein, significant reduction was observed when compared to pretreatment ratios. These data suggest that vitamin E acts at the step mediated by vitamin K and not in the synthesis of the factor II precursor. Although the administration of high doses of vitamin E in animals, and possibly humans, with vitamin K deficiency potentiates the vitamin K deficiency, this effect is not clinically obvious with 400 IU/day or less.
D000328:Adult; D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D006801:Humans; D008297:Male; D011516:Prothrombin / Q000378:metabolism*; D051381:Rats; D014810:Vitamin E / Q000494:pharmacology*; D014813:Vitamin K Deficiency / Q000139:chemically induced / Q000378:metabolism*; D014859:Warfarin
D014810:Vitamin E; D014859:Warfarin; D011516:Prothrombin