ORAL EFFECTIVENESS OF D,L-THYROXINE IN CRYSTALLINE, MONOSODIUM, AND DISODIUM FORMS

Abstract

An investigation was conducted to determine the relative oral effectiveness of crystalline, monosodium, and disodium D,L-thyroxine in the domestic fowl. 0.000,074% of crystalline D,L-thyroxine in the feed was the amt. necessary to maintain the thyroids of thiouracil-treated male chicks at normal wt. Likewise, 0.000,078% was the amt. required by the females. The requirements of the male chicks for the monosodium and disodium salts were 0.000,035% and 0.000,038%, respectively. The comparative figures for the females were 0.000,036% and 0.000,039%. It was calculated that crystalline thyroxine was absorbed to the extent of approx. 20% and the Na salts, about 45%.