Pharmacokinetic model of florfenicol in turbot (Scophthalmus maximus): establishment of optimal dosage and administration in medicated feed

The pharmacokinetics of florfenicol (FF) in turbot (Scophthalmus maximus) was studied after single intravenous (10 mg kg−1) and oral (100 mg kg−1) administration. The plasma concentration–time data of florfenicol were described by an open one‐compartment model. The elimination half‐life (t1/2) was estimated to be 21.0 h, and the total body clearance, Cl, was determined as 0.028 L kg h−1. The apparent volume distribution (Vd) was calculated to be 0.86 L kg−1and the mean residence time (MRTiv) was 30.2 h. Following oral administration, the maximum plasma concentration (Cmax) of 55.4 μg mL−1was reached at 12 h (Tmax). The absorption constant (ka) was 0.158 h−1. The bioavailability was estimated to be 57.1%. The low bioavailability observed at higher doses was explained by the saturation of the mechanisms of absorption. The drug absorption process was limited by its inherent low solubility, which limited the amount of availableFFabsorbed in the gastrointestinal tract. Based on the pharmacokinetic data, an optimal dosing schedule forFFadministration is hereby provided. Based on the minimum inhibitory concentration found for susceptible strains ofAeromonas salmonicida, oralFFadministration of first, an initial dose of 30 mgFF kg−1, followed by 6 maintenance doses at 18 mg kg−1/daily could be effective against furunculosis in turbot.