Abstract
6-(l[image]]-Methyl-4[image]-nitro-5[image]-imidazolyl)-mercapto-purine had an LD50 intraperitoneally (i.p.) for the mother animals of 300 mg/kg and a lethal litter effect on the 7th day of gestation at a dose of approximately 10 mg/kg i.p. 2-Amino-6-(l[image]-methyl-4[image]-nitro-5[image]-imidazolyl)-mercaptopurine had an LD50 of above 300 mg/kg and had a lethal effect on the litter when given in 5 mg/kg doses on the 7th day of gestation. Both compounds induced severe stunting in the surviving fetuses, especially when given over longer periods of time. Gross malformations of the surviving fetuses were not noted. A few giant placentas were found with stunted fetuses.