Tc-99m-labeling experiments on CCK4 by a direct method

Tc-99m-labeling studies have been performed on CCK, fragment of cholecystok inin, starting from Tc-99m-pertechnetate, by using tin(II)pyrophosphate or tin(II)gluconate as reducing agents, together with NaBH4 acting as a stabil izing agent of tin(II). Gluconate has been used as exchange ligand in the c arrier added experiments and in the syntheses of Tc-99-CCK4 and Re-CCK4 com plexes to be able to reproduce at macroscopic level the same chemical react ions occurring at non carrier added conditions. 99mTc-labeling yields highe r than 95% have been achieved depending on Sn(II) concentration, CCK4/gluco nate ratio, reaction time and applied temperature. The species produced wit h Tc-99m, Tc-99, and cold rhenium nuclides have been compared by means of H PLC measurements, which showed similar retention times and thus probably th e same species in the three situations. (C) 2001 Elsevier Science Inc. All rights reserved.