Synthesis of a bis(2,3-dimethylcyclohexyl-dithiocarbamato)-nitrido 99mTc complex: A potential tracer for myocardial imaging

The 99mTcN(DMCHDTC)2 complex, where DMCHDTC is 2,3-dimethylcyclohexyl dithiocarbamato, has been synthesized through a ligand-exchange reaction. The two-step procedure involved the initial reaction of 99mTcO4− with succinic dihydrazide in the presence of stannous chloride as reducing agent and propylenediamine tetraacetic acid as complexant, followed by the addition of 2,3-dimethylcyclohexyl dithiocarbamate. The radiochemical purity of the complex was over 90%, as measured by thin layer chromatography, without any notable decomposition at room temperature over a period of 6 h. The partition coefficient and electrophoresis results indicated that this complex was lipophilic and neutral. Biodistribution in mice showed that the complex accumulated in the heart with high uptake and good retention, the heart uptakes being 12.82, 11.37 and 10.64%ID/g at 5, 30 and 60 min post-injection, respectively. The heart/lung, heart/liver and heart/blood ratios of the complex were 1.06, 0.25 and 8.06 at 60 min post-injection, suggesting it has potential for use as a myocardial imaging agent.