Pharmacokinetics of danofloxacin in rainbow trout after different routes of administration

Abstract

The pharmacokinetics of danofloxacin was studied in rainbow trout (Oncorhynchus mykiss) after single administration by intravenous (IV), intramuscular (IM) and oral (OR) gavage at a dose of 10 mg/kg and by 10 mg/L bath for 2 h at 11.7 ± 0.8 °C. Furthermore, minimal inhibitory concentrations (MICs) of danofloxacin against a pathogenic strain of Yersinia ruckeri, Pseudomonas spp., and Aeromonas hydrophila were determined. Plasma concentrations of danofloxacin were determined using high-performance liquid chromatograph - UV and further subjected to noncompartmental analysis. Elimination half-lives for IV, IM, OR and bath administration were 25.97 h, 42.43 h, 41.04 h and 40.41 h, respectively. Peak plasma concentrations (Cmax) for IM, OR and bath administration were 3.64 ± 0.12, 2.93 ± 0.23, and 0.36 ± 0.02 μg/mL, respectively. Bioavailability was 105.87% (IM), 96.92% (OR) and 10.09% (bath). MIC values were 0.02 μg/mL for Y. ruckeri, 3.2 μg/mL for Pseudomonas spp., and 8 μg/mL for A. hydrophila at 12 °C. Danofloxacin provides the desired AUC0–24/MIC (≥125) and Cmax/MIC (≥10) values for Y. ruckeri following administration at a dose of 10 mg/kg (L) from all routes administration, whereas inadequate for Pseudomonas spp. and A. hydrophila. This information may help in the use of danofloxacin in rainbow trout, but increasing doses pharmacokinetics with the residue depletion study and clinical studies in infected fish are needed.