Pharmacokinetics of Difloxacin in Turbot (Scophthalmus maximus) Following Intravenous and Oral Administration

Abstract:

To investigate the pharmacokinetics of difloxacin in Scophthalmus maximus after intravenous and oral administration at 14−17℃ water temperature, several tissues and plasmas were collected at various time points to calculate the dosage regimen of difloxacin. Five fish were randomly selected from the tank and sampled at 15, 30 min and 1, 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h after intravenous and oral administration, respectively. The concentration of difloxacin was determined by the High Performance Liquid Chromatography. The data were analyzed with the pharmacokinetic program DAS 2.0. The results showed that the plasma concentration of difloxacin at each time point was best described as a two-compartment open model. The elimination half-life (t1/2β) was 30.02 h for intravenous administration, and the area under concentration-time curve (AUC0-t) was 440.37 h•μg/ml. The peak concentration (Cmax) by oral administration was 6.32 μg/ml at 4 h, and t1/2β was 94.72 h, and AUC0-t was 246.66 h•μg/ml. The concentration in muscle and kidney was higher than that in liver by oral administration. According to the difloxacin pharmacokinetics and the minimal inhibitory concentration of most fish bacterial pathogens, the recommended dosage of difloxacin was 11.94 mg/kg once per day by oral administration.