PHARMACOKINETI CS OF FLORFENICOL IN CHANNEL CATFISH (ICTALURUS PUNCTATUS) AT D IFFERENTWATER TEM PERATURES

The pharmacokinetics of florfenicol (FF) was investigated with a single doe of.0mg/kg body weight after oral gavage administration in channel catfish (Ictalurus punctatus) at the water temperature of 18℃ and 28℃.Florfenicol and its metabolite FlorfenicolAmine (FFA) concentrations in fish p lasma were simultaneously determined using high-perform-ance liquid chromatography (HPLC) with UV detection.Pharmacokinetic parameters were calculated by using the 3p97 Practical Pharmacokinetic Program software.The results showed that the kinetics of the drug was found to be temperature dependent.Plasma concentration-time data of florfenicol were best fitted using a one-compartmental open model at both 18℃ and 28℃ water temperature.The kinetic equation were Cp lasma=7.921 (e -0.036t-e-0.180t) and Cp lasma=9.061 (e-0.08.t-e-0.30.1t) at 18℃ and 28℃ respectively.The major pharmacokinetic parameters atwater temperature of 18℃ and 28℃ were as follows: the absorp tion half-time (T1/2kα) 3.845h and 2.301h, respectively; the elimination half-time (T1/2ke) 19.118h and 8.519h, respectively; The time point of the maximum p lasma concentration (Tp) 1.1136h and 5.953h respectively, Peak p lasma concentration (Cmax) were 4.074μg/mL and 4.226μg/mL, respectively;Area under curve (AUC) 174.547μg/mL·h and 8.1279μg/mL·h, respectively; Mean residence time (MRT) were 27.58.h and 12.290h, respectively.Relatively apparent distributed volume V/F (c) were app roached that were 1.512L/kg and 1.580L/kg respectively.Florfenicol administration for p reventing and controlling bacterial disease of channel catfish which is recommended to be once two days at 18℃ or once a day at 28℃with a doe of 10mg/kg bodyweight by oral administration.The main metablite FFA of FF was-not detected in channel catfish p lasma samp le.