Radiolabeling of Ciprofloxacin with Technetium-99m, Quality Control and Biodistribution

Radiolabeled antibiotics are used for the specific diagnosis of infection by exploiting their specific binding properties to the bacterial components, thereby making it possible to differentiate infection from sterile lesions. 99mTc-ciprofloxacin is the most widely used infection imaging agent which belongs to quinolones group and has a vast antimicrobial action against bacterias. Ciprofloxacin  binds to bacterial DNA Gyrase and inhibits its conventional synthesis. Ciprofloxacin labeled with 99mTc specifically binds to various bacteria. Thus, it potentially constitutes a specific marker allowing discrimination between septic and aseptic diseases. In this paper, we describe the labeling of ciprofloxacin with the most widely used imaging radionuclide, 99mTc. The quality control procedure using thin layer chromatography and the stability of labeled compound and also the effect of different parameters such as pH and stannous chloride amount on the radiolabeling yield were investigated. The maximum radiochemical yield was 90±3%. The stability of the radiolabeled antibiotic in the presence of human serum was about 84.2% and 79.6%, respectively after 1h and 4h. 75% of the activity binds to the plasma proteins and the ratio of infected muscle to non-infected muscle is 3.2 and 1.8, 1h and 4 hours post injection.