Thiouracil Derivatives of Greater Activity for the Treatment of Hyperthyroidism1

Abstract

Two derivatives of thiouracil which had been found to be approx. 10 times as active as thiouracil in animal tests have been used for the treatment of hyperthyroidism. Fourteen patients were treated with 6-ethylthiouracil; 8 of these and 29 others were given 6-n-propylthiouracil. The only side effect encountered was a single instance of an urticarial reaction from the ethyl derivative. It was estimated that 25 mg. of propylthiouracil at 8 or 12 hr. intervals is an adequate dose to restore metabolic equilibrium and that this state can be maintained by a daily dose of 25-50 mg. It is concluded that these compounds are about 5 times as active in man as thiouracil and are superior to thiouracil for the treatment of hyperthyroidism.