Preparation,quality control and stability of 99mTc‐sparafloxacin complex,a novel agent for detecting sites of infection

Labeling of sparafloxacin with technetium‐99m using stannous chloride as a reducing agent was investigated. Dependence of the yield of ^99mTc‐sparafloxacin complex on the concentration of sparafloxacin, reducing agent, pH and reaction time was studied. Under optimum conditions, the labeling yield of ^99mTc‐sparafloxacin complex (95%) was achieved by using 2.5 mg of sparafloxacin, 50 µg of Sn(II), pH 10 and 30‐min reaction time. ^99mTc‐sparafloxacin complex was stable for 3 h after labeling, then the yield decreased gradually to 81.9% at 6 h. Biodistribution studies in rats were carried out in experimentally induced infection in the left thigh using Staphylococcus aureus. The ratios of bacterial infected thigh/contralateral thigh were then evaluated. The time for the maximum accumulation of ^99mTc‐sparafloxacin at the site of the infection was 30 min after the administration followed by gradual decline. The abscess‐to‐muscle ratio for ^99mTc‐sparafloxacin was 5.9±0.7, while that for the commercially available ^99mTc‐ciprofloxacin was 3.8±0.5 under the same experimental paradigm, indicating that ^99mTc‐sparafloxacin could be used for infection imaging. Copyright © 2009 John Wiley & Sons, Ltd.