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

Abstract

The pharmacokinetics of florfenicol (FF) in turbot(Scophthalmusmaximus) was studied aftersingle intravenous (10mgkg-1 ) and oral (100mgkg-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 21.0h, and the total body clearance, Cl, was determined as 0.028Lkgh-1 . The apparent volume distribution (Vd ) was calculated to be 0.86Lkg-1 and the mean residence time (MRTiv ) was 30.2h. Following oral administration, the maximum plasma concentration (Cmax ) of 55.4μgmL-1 was reached at 12h (Tmax ). The absorption constant (ka ) was 0.158h-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 available FF absorbed in the gastrointestinal tract. Based on the pharmacokinetic data, an optimal dosing schedule for FF administration is hereby provided. Based on the minimum inhibitory concentration found for susceptible strains of Aeromonassalmonicida, oral FF administration of first, an initial dose of 30mg FFkg-1 , followed by 6 maintenance doses at 18mgkg-1 /daily could be effective against furunculosis in turbot.