Effect of Lactic Acid on Enrofloxacin Pharmacokinetics in Eriocheir Sinensis (chinese Mitten Crab)

As a representative acidifier, lactic acid (LA) is widely used in the diets of aquatic animals. LA is the main supporter of energy metabolism and may be associated with drug metabolism. This study was designed to explore the pharmacokinetics of enrofloxacin (ENR) in Eriocheir sinensis (Chinese mitten crab) fed diets containing 0.1%, 0.2% and 0.3% LA (designated groups LA1, LA2 and LA3 respectively). The concentrations of ENR in the haemolymph, hepatopancreas and muscle were determined by HPLC after a single oral dose of 10 mg/kg. Our results showed that LA had a significant effect on the peak ENR concentrations in all the tissues (p < 0.05) by one-way ANOVA analysis. There was a trend that C-max (peak concentration) of ENR was elevated with LA levels increasing up to 0.3% in haemolymph, hepatopancreas, muscle and T-max (time-point of the peak concentration of the drug), t(1/2 beta) (elimination half-life) and AUC((0-infinity)) of ENR were shortened. Taken together, 0.3% LA might be effective in improving ENR pharmacokinetics in E. sinensis. Furthermore, it can be speculated that the enhanced biotransformation of ENR in the hepatopancreas mediated by LA is responsible for the differences in the pharmacokinetics of ENR in E. sinensis.