INFLUENCE OF A (TCN)-TC-99M CORE ON THE BIOLOGICAL AND PHYSICOCHEMICAL BEHAVIOR OF TC-99M COMPLEXES OF L,L-EC AND L,L-ECD

Tc-99m-nitrido complexes of L,L-ethylene dicysteine ((TcN)-Tc-99m-L,L- EC) and (TcN)-Tc-99m-L,L-ethylene dicysteine diethylester ((TcN)-Tc-99 m-L,L-ECD) were prepared and their characteristics compared to those o f the respective Tc-99m-oxo complexes. (TcN)-Tc-99m-L,L-EC and (TcO)-T c-99m-L,L-EC migrate to similar extents during electrophoresis at pH 1 2, but, at pH 6, (TcN)-Tc-99m-L,L-EC migrates further than (TcO)-Tc-99 m-L,L-EC, Renal excretion of (TcN)-Tc-99m-L,L-EC is inferior to that o f (TcO)-Tc-99m-L,L-EC, indicating that the TcN-glycine sequence has lo wer affinity for the renal tubular system. Both (TcO)-Tc-99m-L,L- ECD and (TcN)-Tc-99m-L,L-ECD are neutral, but (TcN)-Tc-99m-L,L-ECD is hydr ophilic and shows minimal brain uptake in both mice and the baboon. Co pyright (C) 1996 Elsevier Science Inc.