Stability of the radiopharmaceutical [99mTc]DMSA: study of the ligand exchange reaction with [99Tc]EDTA.

A kinetic study was made of the ligand exchange reaction between [99mTc]EDTA and DMSA. The results of this study indicate that this exchange reaction is closely related to temperature and pH. Kinetic and thermodynamic parameters demonstrate that both complexes--[99MTc]EDTA and [99mTc]DMSA--have a similar stability. Furthermore, the existence of an acid-basic catalysis for the global exchange reaction was established, and the catalytic parameters were calculated. These data were obtained by radiochromatography and visible spectrophotometry.