Synthesis, characterization, and biodistribution of oxo complexes of technetium-99m with biguanide and N1-substituted ligands.

We report the synthesis, characterization, and biodistribution of 99mTc-complexes with the bidentate-N,N chelate biguanide (Big) and the N1-substituted ligands dimethyl (DMBig), phenyl (PBig), and phenethyl (PEBig). Dynamic gamma-camera studies with 99mTc-Big and 99mTc-DMSA in rabbits indicated distinct renal and urinary excretion profiles. 99mTc-Big was cleared more quickly than 99mTc-DMSA, and for the same acquisition times, the contrast in whole-body images favored 99mTc-Big. Also, the estimated radiation absorbed doses by kidneys and blood for 99mTc-DMSA were significantly higher than for 99mTc-Big. These preliminary studies show that 99mTc-Big has favourable practical and dosimetric features for renal imaging as an alternative to 99mTc-DMSA.