Pharmacokinetics of Florfenicol after Oral Administration in Yellow Catfish, Pelteobagrus fulvidraco

The pharmacokinetics of florfenicol (FF) and its metabolite, florfenicol amine (FFA), were investigated after doses of 10 mg/kg/day were administered orally per os (p.o.) on a single day or on three consecutive days in yellow catfish, Pelteobagrus fulvidraco, raised in water temperatures of 25 C. After a single dose p.o. was administered, the apparent volume of distribution at steady state (Vdss) of FF was computed to be 2.52 L/kg. The Tmax values were in the following order: liver (1.82 h) < kidney (2.26 h) < skin (6.15 h) < muscle (6.32 h) < plasma (7.25 h). These results show that FF and FFA accumulated rapidly in the kidney and liver. The t1/2β values in plasma, muscle, skin, liver, and kidney were 9.63, 15.75, 14.44, 11.55, and 15.75 h, respectively, for FF and 21.66, 15.07, 17.33, 26.65, and 30.13 h, respectively, for FFA. After a single p.o. dose was administered on three consecutive days, the t1/2β values of FF and FFA in skin-on muscle were 17.12 and 13.55 h, respectively. The total concentrations of FF and FFA in skin-on muscle 1, 3, and 5 d after the last administration were 3.39, 0.5, and 0.062 µg/g, respectively.