(99m)Tc-prulifloxacin in artificially infected animals. Radiosynthesis and biological evaluation

The radiosynthesis of 99mTc-Prulifloxacin ((99m)Tc-PRN) was assessed in terms of stability, binding with Staphylococcus aureus (S. aureus), biodistribution in rats (RT) and scintigraphic profile in rabbits (RB). ANIMALS, MATERIAL, METHODS: 99mTc-PRN was synthesized by mixing 25 µg of stannous fluoride (SnF2) with 18.5 MBq of sodium pertechnetate. Thereafter, 0.5 mg of the prufloxacin (PRN) was added to the reaction mixture and the pH was set at 5.1 with 0.01 mol/l HCl. The reaction mixture was incubated at room temperature. The same process was repeated by increasing the concentration of the stannous fluoride from 25 to 250 µg, sodium pertechnetate from 18,5 to 185 MBq and the PRN from 0.5 to 5 mg. The radiochemical stability of the 99mTc-PRN was investigated in higher concentration of the cystein. In-vitro binding investigation was performed using living and heat killed S. aureus to verify specificity of the 99mTc-PRN. Biodistribution was evaluated in artificially infected rats and scintigraphic precision in rabbits at different interval.

The 99mTc-RPN prepared by mixing 2 mg of PRN, 74 MBq sodium pertechnetate, 100 µg stannous fluoride at pH 5.4, appeared to be more than 90% stable with a maximum radiochemical yield of 98.15 ± 0.25% at 30 min. The 99mTc-PRN showed higher stability in serum and satisfactory in-vitro binding to living as compared to heat killed S. aureus. 14.25 ± 0.15% of the injected dose was accumulated in the infected muscle of the model RT. Infected to normal muscle ratio was 5.12 and inflamed to normal muscle was 1.2. The biodistribution was validated by the scintigraphic localization of infection in rabbits.

This investigation of 99mTc-PRN confirmed its momentous radiochemical immovability in saline, serum, preferential in-vitro binding to living bacteria, higher uptake in the infected muscle of model RT and precise localization in the infected muscle of model RB.