Chemical and biological studies of Tc-99m N,N'-bis(mercaptoacetamido)-ethylenediamine: a potential replacement for I-131 iodohippurate.

The tetradentate chelating agent N,N'-bis(benzoylmercaptoacetamido)ethylenediamine was synthesized for evaluation as a potential technetium-99m renal-function radiopharmaceutical. Complexes were prepared using different reducing agents and analyzed by high-performance liquid chromatography. Biological studies were performed in mice, rats, and rabbits and indicated that the new agent is cleared by the kidneys significantly faster than Tc-99m DTPA (p less than 0.01) and slightly slower than I-131 o-iodohippuric acid (p greater than 0.05). There was no evidence of significant renal retention. Renal excretion in all species studied was 70--75% of the injected dose in 30 min; biliary excretion in rats was 7% in animals with normal renal function and 18% in 90 min in the absence of renal function. We conclude that limited clinical trials are warranted.