Single dose pharmacokinetic study of flofenicol in tilapia (Oreochromis niloticus × O. aureus) held in freshwater at 22 °C

Pharmacokinetics, tissue distribution and elimination of florfenicol in tilapia weighing about 98 g held in freshwater at 22 °C were studied after they were given a single oral dose of 10 mg kg− 1 body weight (b.w.). Five fish per sampling point were examined after treatment. Plasma, muscle, liver, kidney, bile and gill were collected and analysed by high-performance liquid chromatography (HPLC) method. Florfenicol was rapidly absorbed from intestine and distributed extensively to extravascular tissues. The maximum concentrations (Cmax) in both plasma and tissues were observed at 12 h (Tmax) and the maximum concentrations in the order of magnitude were bile (10.87 µg g− 1) > kidney (6.89 µg g− 1) > muscle (6.88 µg g− 1) > liver (5.87 µg g− 1) > plasma (4.46 µg ml− 1) > gill (3.22 µg g− 1). The elimination of florfenicol was rapid in plasma, muscle, liver and gill tissue and relatively slow in kidney and bile. The elimination half-lives (T1/2β) in the order of magnitude were bile (36.29 h) > kidney (16.62 h) > gill (15.07 h) > liver (13.94 h) > muscle (10.97 h) > plasma (10.03 h). At 24 h after administration, the drug concentrations in both plasma and tissues remained above the effective treatment concentrations, which can be concluded by comparison with minimal inhibitory concentrations (MICs) as listed in literature, thus florfenicol can be considered as an appropriate treatment for common bacterial infections in fish farming.