Technetium complexes with ligands of pharmacological interest

The synthesis and scintigraphic studies in rats of 99mTc-amino acid complexes containing the Tc=N multiple bond are reported. Chromatographic analysis shows the formation of a multicomponent system affected by tertiary phosphines employed as reducing agents of pertechnetate-99m in the synthesis of the complexes with cysteine (CYS) and cysteine ethyl ester (CYS-OEt), while no influence of them is observed in 99mTc-complexes having cysteamine (CSA) as ligand. Electrophoresis stresses a strong anionic character in all these compounds. It has not been possible to define their chemical identity by a comparison with the neutral technetium-99 nitrido complexes characterized by spectroscopic and X-ray crystallographic data due to the complexity of the 99mTc-system. There complexes are stable at 80°C over a period of 2 hours. Time-activity curves indicate a renal tissue retention only for the 99mTc-(CSA) complexes