Pharmacokinetics, Pharmacodynamics and Depletion of Florfenicol Applied in White Leg Shrimp (Litopenaeus vannamei) Aquaculture and Impact on Shrimp Hepatopancreas Histology

This study aimed to determine pharmacokinetics (PK) parameters of FF in white leg shrimp plasma, hepatopancreas and muscle as well as its residue depletion in shrimp muscle and hepatopancreas, and the impact on shrimp hepatopancreas histology during and after FF medication. In the PK experiment, shrimp were fed once at 10 mg FF/kg body weight (bw) by oral in-feed administration to determine PK parameters in plasma, hepatopancreas and muscle. The maximum concentration (Cmax) of 60.56 μg/L in plasma was observed after 1.77 h (Tmax). In muscle, a Cmax of 11.76 μg/kg was attained after 0.20 h, while in hepatopancreas, the Cmax was higher (386.92 μg/kg) and was rapidly obtained (Tmax= 0.19 h). Cmax values in shrimp plasma were below the minimum inhibitory concentration (MIC) against Vibrio parahaemolyticus, known to cause acute hepatopancreatic necrosis disease (AHPND) in shrimp. FF depletion in white leg shrimp muscle and its histological impact on hepatopancreas were determined after feeding FF medicated feed once a day or twice a day for 3 consecutive days with a dose of 10 mg FF/kg bw. The residues in shrimp muscle were eliminated rapidly, and were below the limit of quantification at 24 h after stopping medication. The withdrawal time of FF in shrimp muscle was 27.9 degree-days (2 days at 26.5 °C) according to the maximum residue limit (MRL) of 100 µg/kg set by the European Commission and Korean Ministry when feeding FF twice a day for 3 days. The results from histological analysis showed that there was no negative effect on shrimp hepatopancreas after stopping medication.