Synthesis and biological distribution of 99mTc–norfloxacin complex, a novel agent for detecting sites of infection

The optimization of the radiolabeling yield of ciprofloxacin analogous, norfloxacin, with technetium-99m (99mTc) was described. Dependence of the labeling yield of 99mTc–norfloxacin complex on the concentration of norfloxacin, SnCl2·2H2O content, pH of the reaction mixture and reaction time was studied. Norfloxacin was labeled with 99mTc at pH 3 with a labeling yield of 95.4% by using 5 mg norfloxacin, 50 μg SnCl2·2H2O and 30 min reaction time. The formed 99mTc–norfloxacin complex was stable for a time up to 3 h. Biological distribution of 99mTc–norfloxacin complex was investigated in experimentally induced inflammation rats using Staphylococcus aureus (bacterial infection model) and heat killed Staphylococcus aureus and turpentine oil (sterile inflammation model). In case of bacterial infection, the T/NT value for 99mTc–norfloxacin complex was found to be 6.9 ± 0.4 which was higher than that of the commercially available 99mTc–ciprofloxacin under the same experimental condition.