Tissue distribution and elimination of norfloxacin in Japanese sea perch (Lateolabras japonicus) and black sea bream (Sparus macrocephalus) following multi-oral administration

Tissue distribution and elimination of Norfloxacin (NFLX) was evaluated in Japanese sea perch and black sea bream following multi-oral administration. Japanese sea perch and black sea bream were treated with NFLX in seawater at a dose of 30 mg/kg weight body per day for five days in 18.4 ± 0.6 °C and 15.7 ± 1.0 °C, respectively. At different times, six Japanese sea perch and black sea bream were randomly selected from the tank and killed after oral administration. Using high-performance liquid chromatography (HPLC); blood, muscle, liver and kidney tissues were analyzed for NFLX. The tissue distribution profile of NFLX in both species was found to be very similar. At the conclusion of the NFLX treatment, tissue concentrations decreased in the following order: kidney > liver > muscle ≈ whole blood. NFLX tissue concentrations in black sea bream were much higher than those of Japanese sea perch. Elimination half-lives of NFLX in the whole blood, muscle, liver and kidney in Japanese sea perch and black sea bream were 5.06, 3.96, 2.37, 1.82d and 4.03, 3.75, 5.33, 3.87d, respectively. The results show that NFLX concentrations in the muscle of Japanese sea perch and black sea bream fell below the 0.01 µg/g detection limit at day 14 and day 32 post-dosing. These results helped the Chinese fishery department establish a reasonable withdrawal period for NFLX in farmed Japanese sea perch and black sea bream.