Plasma and tissue depletion of florfenicol in olive flounder (Paralichthys olivaceus) after oral administration

The aim of this study was to evaluate the pharmacokinetics of florfenicol after intravenous (i.v.) and oral (p.o.) administrations and investigate its depletion after multiple oral administrations for 3 consecutive days in olive flounder (Paralichthys olivaceus). After i.v. injection of 5 mg/kg, the terminal half-life (t1/2λz), the volume of distribution at steady-states (Vss), and the total body clearance of florfenicol were 38.06 ± 6.10 h, 0.62 ± 0.19 l/kg and 0.012 ± 0.001 l kg/h, respectively. After p.o. administration of 20 mg/kg, the t1/2λz, Cmax, Tmax and oral bioavailability (F) of florfenicol were 51.18 ± 8.03 h, 12.18 ± 3.21 μg/ml, 4 h and 43.00 ± 5.71%, respectively. Florfenicol amine, a major metabolite of florfenicol, was not detected in any samples following p.o. and i.v. administrations of florfenicol in olive flounder and this lack of metabolism may well explain the slower elimination of florfenicol in olive flounder. After multiple oral doses (20 mg/kg/day for 3 days), the prolonged presence of residues in various tissues can play an important role in human food safety and tissue disposition of florfenicol in olive flounder. A withdrawal time of 8 days was necessary to ensure that the residues of florfenicol were less than the maximal residue limit of tolerance established by the European Union.