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

Sulfadiazine (antibiotic used for treating bacterial infections) was labeled with 99mTc with the aim of the development of a new radiopharmaceutical for infection imaging. The influence of the reaction parameters such as the substrate and SnCl2·2H2O 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 99mTc-sulfadiazine (94.7%) was obtained by using 50 μg of SnCl2·2H2O 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 99mTc-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 99mTc-sulfadiazine was found to be 3.6, which is comparable to the commercially available 99mTc-ciprofloxacin (3.8), indicating that 99mTc-sulfadiazine can be used for infection imaging. © 2015 Pleiades Publishing, Inc.