The Impact Of Exercise On The Pharmacokinetics And Residues Of Oxytetracyeline In GIFT Strains Of Oreochromis Niloticus

With the increase of tilapia market, the cultivation scale of tilapia was growing in magnitude,bacterial disease, however, broke out frequently because of intensive aquaculture model.Oxytetracycline (OTC), as one of the efficient and broad spectrum antibiotic, is widely used fortreating bacterial disease, but the residues of it would be potentially harmful to the consumers，sothe analysis of the drug’s pharmaeokinetics and residue elimination had a significantimplicaction. Fish had a trend of countercurrent forward, possibly resulting in changing the taste,nutritive value, and physiological metabolism of fish cultived in running water. In this paper, theimpact of exercise on the pharmaeokinetics and residue elimination of oxytetracyeline in GIFTstrains of Oreochromis niloticus was researched, in order to provide a scientific basis of rationaluse of drugs, improvement of the quality and safety of aquatic products, and cuting of thewithdrawal period.OTC in aqueous solution in a single dose of50mg/kg body weight is orally administered toGIFT strains of O. niloticus (weight88.0±13.0g) for pharmaeokinetics studyes, and a dose of50mg/kg body weight for5days was taken to study residues of OTC in running water (0.2m/s)and still water, respectively. The concentration of OTC residues in fish tissues was determined byhigh performance liquid chromatography. The results were as following:Pharmaeokinetics data of the GIFT plasma fitted a two-compartment model with first-orderadsorption in either running or still water， vizCt=0.158e-1.622(t-0.429)+0.096e-0.074(t-0.429)-0.254e-3.924(t-0.429)andCt=0.063e-0.053(t-0.279)+0.037e-0.021(t-0.279)-0.1e-3.404(t-0.279), respectively. The main pharmaeokinetieparameters of running water and still water were0.201h and0.263h of absorptionhalf-life(t1/2ka),0.427h and13.132h of distribution half-life(t1/2α),9.368and33.269h ofelimination half-life (t1/2β),0.671h and1.33h of Tmax,0.117μg/mL and0.093μg/mL of Cmax,and21.95h and44.983h of mean retention time (MRT). It shows that GIFT cultived in therunnig water absorbed, distributed and eliminated the drug more quickly, had the higher drugconcentrations in the plasma, and needed shorter time to remove it. In the experiments of residue elimination of OTC in GIFT, we discovered that either in therunning water or still water the concentrations of OTC in the muscle rised firstly, after two daysup to1.435mg/kg and1.206mg/kg, respectively, and then reduced. beingl below the maximumresidue limit (0.1mg/kg) on th12thand16thday, respectively. In the liver, concentrations of OTCalso rised firstly, reaching11.975mg/kg in running water4days later and7.677mg/kg in thestill water two days later, then reduced gradually, being below the maximum residue limit(0.3mg/kg) on the6thin running water and16thin still water. It showed that exercise can make GIFTabsorbed and eliminated OTC quickly.