On Inhibition of Vit. K Activity by Sulfaquinoxaline in Chicks

Increasing doses of vit. K-active compounds are necessary to overcome the inhibition of prothrombin formation in chicks fed increasing levels of sulfaquinoxaline. The drug will hasten depletion of prothrombin in chicks kept on a K-deficient ration. When a single dose of about 50 mg of sulfaquinoxaline was administered orally with varying levels of menadione, one mole of menadione appeared to overcome the inhibitory effect of more than 800 moles of sulfaquinoxaline.