Pharmacokinetics and tissue distribution of enrofloxacin after single intramuscular injection in Pacific white shrimp

The pharmacokinetic properties and tissue distribution of enrofloxacin (EF) were investigated after single intramuscular (i.m.) dose of 10mg/kg body weight (b.w.) in Pacific white shrimp at 22 to 25 degrees C. EF and its metabolite ciprofloxacin (CF) were determined by high-performance liquid chromatography. After i.m. administration, EF was absorbed quickly, and the peak of EF concentration (C-max) reached at first time point in hemolymph. The volume of distribution V-d(area) of EF was 3.84L/kg, indicating that the distribution of EF was good. The area under the concentration-time curve (AUC) of EF was 90.1 and 274.2ghr/ml in muscle and hepatopancreas, respectively, which was higher than 75.8ghr/ml in hemolymph. The EF elimination was slow in muscle and hepatopancreas with the half-life (T-1/2) of 52.3 and 75.8hr, respectively. CF, the mainly metabolite of EF, was detected in hemolymph, muscle and hepatopancreas. The C-max was 0.030, 0.013 and 0.218g/ml, respectively. Based on a minimum inhibitory concentration (MIC) of 0.006-0.032g/ml for susceptible strains, EF i.m. injected at a dose 10mg/kg could be efficacious against common pathogenic bacteria of Pacific white shrimp.