Biodistribution of 59Fe-thiosemicarbazones

The 59Fe-iron(II) chelates of 2-formylpyridine thiosemicarbazone (I), 5-dimethylamino-2-formylpyridine thiosemicarbazone (II), and 5-hydroxy-2-formylpyridine thiosemicarbazone (III) were prepared and their biodistribution determined in normal rats. Early accumulation of these complexes occurred in the liver, muscle and pelt with lesser amounts in the blood, kidneys and other organs. The tissue levels decreased with a 1 to 2-h half-life with the exception of the liver and intestines. The liver level tended to remain constant over the 2-h period. Accumulation in the gut resulting from hepatobiliary excretion increased over the first 60 min and then leveled off. In rats bearing a subcutaneous glioblastoma the uptake of compound I increased during the first 24 h after administration, and tumor to normal tissue ratios of 2 to 3.3 were obtained.