The discovery of thyroxin in 1915 by Kendall and its subsequent synthesis in 1927 by Harington and Barger was followed by the use of this medicament in racemic form by the physicians of Europe and Latin America. The American physician has not used thyroxin extensively because of the report in 1939 that only a very large dosage was able to maintain the metabolism of the patient with myxedema.1 These studies had led to the conclusion that thyroxin was relatively insoluble and was absorbed from the alimentary canal incompletely and irregularly.2 This belief was contradicted in 1950 by the experience of Hart and Maclagan3 who found that synthetic l-thyroxin given orally, produced by a new method, would correct myxedema in dosage as low as 0.3 mg. per day.
The modern material is synthetic sodium l-thyroxin, i. e., it is not a racemic mixture. Since 1950, a
Starr P, Liebhold-Schueck R. TREATMENT OF HYPOTHYROIDISM WITH SODIUM LEVO-THYROXIN GIVEN ORALLY. JAMA. 1954;155(8):732-736. doi:10.1001/jama.1954.03690260024007