Development and evaluation of a single vial cold kit for infection imaging: Tc-99m Ciprofloxacin

Radiolabeled antibiotics have been used in nuclear medicine for the diagnosis of bacterial infection. They are used as specific infection-imaging agents because of their affinity to bind with bacteria. Tc-99m Ciprofloxacin is the most widely used infection-imaging agent. The aim of the present work is to increase the shelf life of an in house developed single vial kit for the preparation of Tc-99m Ciprofloxacin. Different methods were used to make the Ciprofloxacin kits. Kits were stored at a temperature of 4 deg. C under nitrogen atmosphere and evaluated for stability by serially estimating the labeling efficiency using instant thin layer chromatography (ITLC) following reconstitution with Tc99m pertechnetate at regular intervals of time up to 90 days after their preparation. The data were subjected to Sigmaplotsoftware version 8.0 for shelf-life analysis. The kits were further evaluated for a number of standard quality control parameters. Kits containing sodium chloride-Ciprofloxacin pellets were found to have a shelf life of 7 months and constantly maintaining a labeling efficiency of 95% Tc-99m Ciprofloxacin. Biodistribution studies in balb/c mice showed significant levels in kidney, liver and intestine. Blood clearance studies showed a slow and biphasic clearance in rabbits. Gamma camera imaging of the rabbits bearing S.aureus infectious lesion confirmed the utility and specificity of the reconstituted kit in imaging infection. The final kit, which was recommended for clinical use was found to be stable for nine months with all its characteristics remaining unchanged from those of the freshly prepared Tc-99m Ciprofloxacin during the entire period of observation. (author)