Radiochemical and Biological Characteristics of ¹²⁵I-Diclofenac for Inflammation Sites Detection

The aim of this work was to develop a potential selective radiopharmaceutical agent for the inflammation imaging to monitor the treatment process. Diclofenac was successfully labeled with ¹²⁵I. This labeling reaction was carried out via electrophilic substitution of hydrogen atom with the iodonium ion I⁺. The reaction was found to be strongly dependent on the ph of the reaction medium. At ph 7, the labeling yield was maximum. This may be due to the good solubility of diclofenac, good protonation and good working of the oxidizing agent at this ph value. The labeling reaction was very fast but required 15 min for completion. The produced ¹²⁵I-diclofenac was found stable in-vivo as the thyroid gland uptake did not exceed 0.4 %. Labeled diclofenac showed a good localization in sterile inflamed muscle with T/NT value 9.1 at 4 h post injection. It excreted mainly via the kidney. The imaging must be carried out before 8-hour post injection