CONCENTRATION-TIME PROFILES OF OXYTETRACYCLINE IN BLOOD, KIDNEY AND LIVER OF TENCH (TINCA-TINCA L) AFTER INTRAMUSCULAR ADMINISTRATION

Oxytetracycline (OTC) is a widely-used antibiotic in several animal sp ecies. The Food and Drug Administration allows OTC to be used in fish intended for human food, but there is limited kinetics data available. We studied OTC concentrations in plasma, kidney and liver in tenches (Tinca tinca L) after im administration using HPLC. Concentrations wer e fit to a monocompartment open model by extended least squares regres sion analysis using the MULTI(ELS) computer program. Peaks of OTC conc entrations (C-max) occurred at 4 h for blood and kidney and 72 h for l iver and were 134.1 mu g/mL, 129.8 mu g/g and 333.4 mu g/g, respective ly. There was a high correlation (r=0.9448) between blood and kidney c oncentrations and less between blood and liver. Concentrations were st atistically different for each system. The blood OTC concentrations we re higher than renal concentrations 92% of the time and were higher th an hepatic concentrations 29% of the time. The plasma OTC half-life (2 1.2 h) was longer than in homeothermic species. The tench liver mainta ins considerable OTC residues and may affect food products derived fro m that organ.