Studies On Pharmacokinetics And Residues Of Norfloxacin In Turbot Scophthalmus Maximus

The metabolism of the brine shrimp Artemia fed with Norfloxacin(NFLX) were studied, and the partition and detection methods of NFLX in Artemia were established. The nauplii were sampled after fed with NFLX at different does and different time, the concentrations of NFLX were determined by High Performance Liquid Chromatography(HPLC). The overall recovery was 86.5%~92.8% and the lowest limit of detection concentration was 0.005μg/ml. The result demonstrated that concentration of NFLX in Artemia can achieve its peak value after 8h and it increased with increasing of the doses of NFLX in water, the doses had a little influence on the peaking time.The pharmacokinetics data showed that the concentrations of NFLX in tissues of turbot Scophthalmus maximus were usually higher than the minimum inhibitory concentration(0.25μg/mL) for Vibrio strains. After the fry of Scophthalmus maximus were fed with Artemia enriched with NFLX at the dose of 5, 10mg/kg respectively, NFLX concentration Cmax were 3.33, 2.84μg/mL in the muscle, and were 0.32, 0.21μg/mL after 36h, while Cmax were 10.79, 9.86μg/mL in the bowels, and down to 0.42, 0.311μg/mL after 48h.The concentrations of NFLX in adult turbot were determined by HPLC, and the pharmacokinetic data derived from the experiment were analyzed by MCP-KP practical pharmacokinetics software. The results summarized as follows: (1)The main pharmacokinetic parameters Tmax was about 2h, Cmax was 8.365, 7.519, 1.871, 6.485, 4.060μg/mL(g) in blood, gill, kidney, liver, and muscle respectively, after oral administration at a dose of 30 mg/kg; while t1/2 were 8.180~23.249h. These showed that the NFLX absorption was rapid after oral administration of NFLX in Scophthalmus maximus, but the residence time in the fish was long. (2) T1/2 were 74.88~200.45h after oral administration at dose of 30 mg/kg for five consecutive days, which showed that the attenuation of NFLX in the fish body was slow and the residue concentration in the kidney was the highest.Based on the important culture species Scophthalmus maximus, pharmacokinetics of NFLX were studied at first time. The aim is to provide theorical basis and information in mode , dosage and withdraw of drug application, as well as to guide health management in fish cultivation.