The action of pteroylglutamic acid on blood dyscrasias induced by thiouracil and propylthiouracil.

T HE anti-thyroid drugs, thiouracil and 6 n-propylthiouracil have been reported to cause leukopenia and granulocytopenia in man and experimental animals. ‘ Some evidence has been found to support the view that concurrent administration of liver preparations and folic acid may have beneficial effect on the toxicity of thiourea and thiopyrimidines, including the blood dyscrasias.’#{176} 2 In view of these reports and since Petering, Delor and Murray’3 had shown that concurrent administration of sufficiently large doses of folic acid (pteroylglutamic acid-PGA) retarded the onset of sulfonamide-induced blood dyscrasias in the rat and lessened their severity, it was of considerable interest to carry out similar studies in the rat on the thiopyrimidine-induced blood dyscrasias. It should be emphasized that this work differs from that of other investigators in that the antithyroid drugs and the folic acid preparations were administered together during the entire course of the experiments.