Distribution of Unbound Reduced Technetium-99m in Animals

Abstract

In order to assess the distribution of radioactive contaminants of common radiopharmaceuticals, unbound reduced Tc-99m at three different pH levels was injected into rabbit, dog, and rhesus monkey. Animals were monitored for 24 hr after Tc-99m injection with static images taken at selected times. Localization of unbound reduced Tc-99m was remarkably constant from species to species and at all three pH levels. Localization of this compound reflects the distribution of reticuloendothelial cells. The wide variance between the distribution of unbound reduced Tc-99m and that of free pertechnetate permits identification of either contaminant in radiopharmaceutical preparations.