Radiolabeling, quality control, and biodistribution of 99mTc-sulfadiazine as an infection imaging agent

Abstract—Sulfadiazine (antibiotic used for treating bacterial infections) was labeled with 99m Tc with the aim of the development of a new radiopharmaceutical for infection imaging. The influence of the reaction parameters such as the substrate and SnCl 2 ·2H 2 O concentrations, pH of the reaction mixture, and reaction time on the labeling yield was examined, and the labeling conditions were optimized. The maximum radiochemical yield of 99m Tc-sulfadiazine (94.7%) was obtained by using 50 µg of SnCl 2 ·2H 2 O and 1 mg of sulfadiazine at pH 5. The radiochemical purity of the labeled compound was evaluated by ITLC and HPLC. The biological distribution of 99m Tc-sulfadiazine in mice with experimentally induced Staphylococcus aureus infection in the right thigh was studied, and the bacterial infected thigh/normal thigh (target-to-nontarget, T/NT) ratio was evaluated. The T/NT ratio for 99m Tc-sulfadiazine was found to be 3.6, which is comparable to the commercially available 99m Tc-ciprofloxacin (3.8), indicating that 99m Tc-sulfadiazine can be used for infection imaging.