Synthesis of a bis-(N-sec-butyl-dithiocarbamato)-nitrido-99mTc complex: a potential new radiopharmaceutical for brain perfusion studies

A bis-(N-sec-butyl dithiocarbamato) nitrido technetium-99m complex [99mTcN(SBDTC)2] (SBDTC: N-sec-butyl dithiocarbamato) was synthesized by the reduction of 99mTcO4− to [99mTc≡N]2+ with stannous chloride in the presence of succinic dihydrazide and propylenediamine tetraacetic acid, followed by the addition of sodium N-sec-butyl dithiocarbamate dihydrate. The radiochemical purity of the complex was over 90% as measured by thin layer chromatography. It was stable over 6 h at room temperature. Its partition coefficient indicated that it was a good lipophilic complex. The electrophoresis results showed that the complex was neutral. Biodistribution studies in mice demonstrated that the complex accumulated in the brain with high uptake and good retention. The brain uptake (ID%/g) was 3.89, 3.44 and 2.82 and the brain/blood ratio was 1.41, 1.45, 1.00 at 5, 30 and 60 min post-injection respectively. These results suggested the potential usefulness of the complex as a brain perfusion imaging agent.