Temperature-dependent pharmacokinetics of florfenicol in Nile tilapia (Oreochromis niloticus) following single oral and intravenous administration

Abstract Temperature-dependent pharmacokinetics (PK) have rarely been reported in tilapia despite there are popularly cultured worldwide, ranging from tropical to temperate climates. The present study aims to investigate the PK characteristics of florfenicol (FF) in Nile tilapia at 3 temperature levels (24, 28, and 32 °C) after single intravenous (IV) and oral (PO) dose of 15 mg/kg to evaluate the effects of temperature on PK. The serum concentrations of FF were analyzed by HPLC-UV method and PK characteristics were analyzed by 2-compartmental model. It was revealed that temperature has profound influences on certain PK parameters. The results from both IV and PO experiments were generally similar. Increasing water temperature from 24 to 32 °C led to significantly increased elimination rate constant (β) from 0.056 to 0.095 1/h and shortened elimination half-life (t 1/2β ) from 12–13 h to 7–8 h. The absorption half-life (t 1/2Ka ) were decreased from 2.28 to 1.18 h as well as the maximum serum concentration (C max ) from 23.14 to 16.71 μg/mL and time to reach C max (T max ) from 1.40 to 0.75 h. The area under the serum concentration-time curves (AUC) were reduced by half while the clearances were doubled and the volume of distributions (Vd) were significantly increased. Our results also demonstrated that for FF in Nile tilapia the temperature coefficient (Q 10 ) values could be applied to predict the CL and β at a specific temperature with high accuracy (94–116%). The temperature-sensitive PK parameters such as the increase in Ka, Vd, and β significantly affected the serum concentrations and its overall exposure (AUC), thereby could potentially implicate that proper dosing regimen should take water temperature into consideration. The study highlighted the possibility of water temperature effect on therapeutic outcome of FF used in tilapia and likely other cichlids.