Determination of pharmacokinetic parameters and tissue distribution characters of enrofloxacin and its metabolite ciprofloxacin in Procambarus clarkii after two routes of administration

Abstract Enrofloxacin (ENR) is widely used for treatment and prevention of bacterial pathogen infections in aquatic animals. However, limited knowledge on kinetic disposal process of ENR in crayfish (Procambrus clarkii). Therefore, the objective of this study was to explore the pharmacokinetics (PK) and tissue distribution regularities of ENR and its predominate metabolite, ciprofloxian (CIP), in crayfish following oral (PO) and intramuscular (IM) administrations. ENR and CIP concentrations in crayfish hemolymph and tissues were determined using ultra performance liquid chromatography coupled to fluorescence detection (UPLC-FLR). PK parameters of targets in hemolymph and tissues were calculated using WinNolin software based on the non-compartmental analysis. Comparative PK parameters in hemolymph showed that higher absorption and longer elimination half-life following IM route than PO treatment. For tissue distribution, high concentrations of ENR and CIP were found in hepatopancreas, and ENR and CIP levels in tissues after IM administration were higher than PO administration. The AUC0-∞ ratios of CIP and ENR in crayfish following PO and IM routes were only 1.25% and 3.56% (hemolymph), 0.71% and 6.89% (muscle), 1.03% and 1.75% (hepatopancreas), 0.65% and 6.46% (gill), respectively, and it indicated that crayfish has a low ability to transform ENR to CIP. ENR regimen suggested against susceptible strains with the minimum inhibition concentration (MIC) below 0.72 μg/mL (IM) and 0.50 μg/mL (PO) based on the values of Cmax/MIC > 8 and AUC/MIC > 125. It could serve as reference data for ENR use in crayfish and provide valuable information for the better utilization of ENR in aquatic animals.