Preparation and biodistribution of 99mTc-lomefloxacin and 99mTc-ofloxacin complexes

This paper addresses the development of two new radiopharmaceuticals for infection imaging. The optimization of the labeling yield of ciprofloxacin analogous, lomefloxacin and ofloxacin, with 99mTc is described. 99mTc-lomefloxacin was obtained with a radiochemical yield of 93.6% by adding 99mTc to 2.5 mg lomefloxacin in the presence of 50 μg SnCl2 while 99mTc-ofloxacin was obtained (96.6%) by adding 99mTc to 2 mg ofloxacin in the presence of 50 μg SnCl2. Biodistribution studies in rats were carried out in experimentally induced infection in the left thigh using Staphylococcus aureus. Both thighs of the rats were dissected and counted and the ratio of bacterial infected thigh/contralateral thigh was then evaluated. 99mTc-lomefloxacin showed higher uptake (T/NT = 6.5±0.5) in the infectious lesion than 99mTc-ofloxacin (T/NT = 4.3±0.6) and abscess-to-muscle ratios for both preparations were higher than that of 99mTc-ciprofloxacin (T/NT = 3.8±0.8), indicating that 99mTc-lomefloxacin could be used for infection imaging. (author)