[99mTc(N)(DASD)(PNPn)]+ Compounds as Myocardial Perfusion Imaging Agents.

[99mTc]TcN-DBODC5 (DBODC=bis(N-ethoxyethyl)-dithiocarbamate; 5=bis(dimethoxypropylphosphinoethyl)-ethoxyethylamine) is the lead candidate of a series of monocationic mixed ligand complexes proposed as myocardial perfusion imaging agents (MPIAs). Phase I clinical trials showed that although the good pharmacokinetics of this agent allows better imaging quality and a superior clinical value in detection of CAD over [99mTc]Tc–Sestamibi, its clinical features seem to resemble those of [99mTc]Tc–Tetrofosmin, failing to entirely reproduce the promising results attained in preclinical studies. Therefore, modifications of [99mTc]TcN-DBODC5 structure are needed to improve its pharmacokinetics, obtaining an ideal MPIA. Here, we present the synthesis, characterization and biological evaluation of four new cationic heteroleptic [99mTc]Tc-nitrido-complexes of general formula [99mTc][TcN-DASD(n)]+ proposed as improved MPIAs, where DASD is 1,4-dioxa-8-azaspiro[4,5]decan-dithiocarbamate and n is a bisphosphinoamine.