Pharmacokinetics of enrofloxacin in snakehead fish, Channa argus

The pharmacokinetics of enrofloxacin (EF) was investigated after single intravenous (i.v.) and oral (p.o.) dose of 10 mg/kg body weight (b.w.) in snakehead fish at 24-26 °C. The plasma concentrations of EF and its metabolite ciprofloxacin (CF) were determined by high-performance liquid chromatography. The plasma concentration-time data were described by an open two-compartment model for both routes. After intravenous administration, the elimination half-life (T1/2β ), area under the concentration-time curve (AUC) and total body clearance of EF were 19.82 h, 75.79 μg h/mL and 0.13 L/h/kg, respectively. Following p.o. administration, the maximum plasma concentration (Cmax ), T1/2β and AUC of EF were 1.86 μg/mL, 35.8 h and 49.98 μg h/mL, respectively. Absorption of EF was good with a bioavailability (F) of 65.82%, which was higher than that calculated in most seawater fish. CF, an active metabolite of EF, was detected occasionally in this study, which indicates a low extent of deethylation of EF in snakehead fish.