Comparative pharmacokinetics of enrofloxacin in healthy and Aeromonas hydrophila-infected crucian carp (Carassius auratus gibelio).

The comparative pharmacokinetics of enrofloxacin (ENR) and its metabolite ciprofloxacin (CIP) were investigated in healthy and Aeromonas hydrophila-infected crucian carp after a single oral (p.o.) administration at a dose of 10 mg/kg at 25 °C. The plasma concentrations of ENR and of CIP were determined by HPLC. Pharmacokinetic parameters were calculated based on mean ENR concentrations by noncompartmental modeling. In healthy fish, the elimination half-life (T1/2λz ), maximum plasma concentration (Cmax ), time to peak (Tmax ), and area under the concentration-time curve (AUC) values were 64.66 h, 3.55 μg/mL, 0.5 h, and 163.04 μg·h/mL, respectively. In infected carp, by contrast, the corresponding values were 73.70 h, 2.66 μg/mL, 0.75 h, and 137.43 μg·h/mL, and the absorption and elimination of ENR were slower following oral administration. Very low levels of CIP were detected, which indicates a low extent of deethylation of ENR in crucian carp.