Enrofloxacin kinetics in hemolymoh of the freshwater crayfish Astacus leptodactylus following bath administration

Abstract

The purpose of this study was to investigate the hemolymph kinetics of enrofloxacin (ENR) following bath immersion administration in freshwater crayfish Astacus leptodactylus. A bath immersion concentration of 30 mg/l for 24h was used in this study. Hemolymph was collected from medicated crayfish prior to, and at 30 min, 1, 2, 4, 6, 12, 24, 48, 96, 144 and 192 h after bath exposure to the drug. The concentration of ENR in hemolymph was determined using a microbiological assay. The hemolymph concentrations of ENR after bath immersion dosing were best described by a two- compartment open model. The mean peak hemolymph concentration (C max) was 6 μg/ml. The elimination half-life of the terminal part of the elimination phase (T1/2β ) was obtained to be 38.5 h. The mean hemolymph concentration of enrofloxacin at 196 h post dosing easily exceeds the in vitro minimum inhibitory concentration (MIC) for most bacterial pathogens infecting fish and shrimp. Results from the present study suggest that it is possible and practical to obtain therapeutic hemolymph concentration of ENR in the Astacus leptodactylus using bath immersion administration.