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 10 mg/kg body weight (b.w.) in Pacific white shrimp at 22 to 25°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 3.84 L/kg, indicating that the distribution of EF was good. The area under the concentration–time curve ( AUC ) of EF was 90.1 and 274.2 μg hr/ml in muscle and hepatopancreas, respectively, which was higher than 75.8 μg hr/ml in hemolymph. The EF elimination was slow in muscle and hepatopancreas with the half‐life ( T 1/2β ) of 52.3 and 75.8 hr, respectively. CF , the mainly metabolite of EF , was detected in hemolymph, muscle and hepatopancreas. The C max was 0.030, 0.013 and 0.218 μg/ml, respectively. Based on a minimum inhibitory concentration ( MIC ) of 0.006–0.032 μg/ml for susceptible strains, EF i.m. injected at a dose 10 mg/kg could be efficacious against common pathogenic bacteria of Pacific white shrimp.