Technetium-99m radiopharmaceuticals containing a technetium-nitrido group

A method is described for the preparation of 99Tcsup(m) complexes containing a 99Tcsup(m)-nitrido group by substitution reactions of 99Tcsup(m)NCl4sup(bar). The properties of these complexes differ from those prepared by conventional reduction methods. As an example, the biological properties of the dimercaptosuccinic acid (DMSA) complex prepared by substitution of 99Tcsup(m)NCl4sup(bar) are compared with those of the complex prepared by reducing 99Tcsup(m)O4sup(bar) with HCl and reacting with DMSA. Compared with the 99Tcsup(m)-DMSA (HCl) preparation, significant bone uptake in mice, lower blood and kidney activity and higher urine activity was shown for 99Tcsup(m)N-DMSA. The complex 99Tcsup(m)NCl4sup(bar) was also used for the labelling of monoclonal antibodies. Monoclonal antibodies labelled with 99Tcsup(m) were shown to retain their specificity after labelling with this agent. (author)