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

Abstract

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 monomelic DTS complex of technetium (^99mTc), a DTS containing ligand, kethoxal-bis(thiosemicarbazone) (KTS) was selected. A well known monomelic 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.