Mononuclear and dinuclear complexes of 99mTc

Labeling of penicillamine di sulfide with technetium-99m

Complex forming conditions of Penicillamine di sulfide with 99mTc have been specified. Labeling of penicillamine di sulfide with 99mTc by direct reduction with SnCl2 did not give favorable good results while the 99mTc complex of penicillamine can be easily obtained. Ligand exchange reaction with 99mTc-gluconate was attempted and a 95% labeling efficiency was obtained. Radiopharmaceutical potential of 99mTc-PADS (99mTc-Penicillamine di sulfide) has been investigated with a gamma camera in rabbits and the complex was found to be uptaken mostly by the liver and kidneys.

In the procurement of a neutral and compact monomeric complex of dithiosemicarbazone (DTS) derivative: 99mTc-KTS

As a basic structure of a bifunctional radiopharmaceutical (BR), dithiosemicarbazone (DTS) enables the formation of a small conjugated chelating ring with divalent metals (Cu2+, Zn2+, Ni2+), yielding stable and compact complexes. In the development of a neutral and compact monomeric DTS complex of technetium (99mTc), a DTS containing ligand, kethoxal-bis(thiosemicarbazone) (KTS) was selected. A well known monomeric Cu-KTS complex (or 64Cu-KTS) is taken as a model compound, and in vitro (TLC, EP, HPLC) and in vivo (mice biodistribution) studies were compared. Using the stannous chloride method, under conditions to avoid the hydrolytic polynucleation of technetium, a good yield of 99mTc-KTS with characteristics resembling the non-charged, compact and stable Cu-KTS is obtained, in in vitro as well as in vivo studies. The importance of DTS as the constituent of a BR is discussed.