Preparation and biological distribution of 99mTc-cefazolin complex, a novel agent for detecting sites of infection

Abstract

The optimization of the radiolabeling yield of cefazolin with 99mTc was described. Dependence of the labeling yield of 99mTc-cefazolin complex on the amounts of cefazolin and SnCl2·2H2O, pH and reaction time was studied. Cefazolin was labeled with 99mTc with a labeling yield of 89.5 % by using 1 mg cefazolin, 5 μg SnCl2·2H2O at pH 4 and 30 min reaction time. The radiochemical purity of 99mTc-cefazolin was evaluated with ITLC. The formed 99mTc-cefazolin complex was stable for a time up to 3 h, after that the labeling yield decreased 64.0 % at 8 h. Biological distribution of 99mTc-cefazolin complex was investigated in experimentally induced inflammation mice, in the left thigh, using Staphylococcus aureus (bacterial infection model) and turpentine oil (sterile inflammation model). Both thighs of the mice were dissected and counted and the ratio of bacterial infected thigh/contralateral thigh was then evaluated. In case of bacterial infection, T/NT for 99mTc-cefazolin complex was 8.57 ± 0.4 after 0.5 h, which was higher than that of the commercially available 99mTc-ciprofloxacin under the same experimental conditions. The ability of 99mTc-cefazolin to differentiate between septic and aseptic inflammation indicates that 99mTc-cefazolin could undergo further clinical trials to be used for imaging sites of infection.