Pharmacokinetics and Tissue Distribution of Thiamphenicol and Florfenicol in Pacific White Shrimp Litopenaeus vannamei in Freshwater following Oral Administration

Abstract

This study evaluated the pharmacokinetic disposition of thiamphenicol (THA) and florfenicol (FLR) after oral administration of each at a single dose of 10 mg/kg body weight in Pacific white shrimp Litopenaeus vannamei held in freshwater at 25.0 ± 1.0°C. The THA and FLR concentrations in the hemolymph, muscle, and hepatopancreas were determined by HPLC. The profiles of hemolymph THA and FLR concentrations versus time were best described by a two-compartment open pharmacokinetic model with first-order absorption. The peak concentration (C _max), peak time (T _max), absorption half-life (t _1/2ka) and elimination half-life (t _1/2β) of THA in hemolymph were 7.96 μg/mL, 2 h, 0.666 h, and 10.659 h, respectively. The corresponding values for FLR were 5.53 μg/mL, 2 h, 1.069 h, and 17.360 h, respectively. After oral administration, THA and FLR were rapidly absorbed in white shrimp and THA in hemolymph was absorbed and eliminated more quickly than FLR. The parameters in muscle and hepatopancreas were calculated by a noncompartment model based on statistical moment theory. The C _max, area under the concentration–time curve (AUC_0-t ), mean residue time (MRT_0-t ), and half-life (t _1/2z) in muscle were 2.98 μg/g, 29.10 mg/kg·h, 9.77 h, and 6.84 h, respectively. The corresponding values for FLR were 1.91 μg/g, 15.97 mg/kg·h, 19.40 h, and 18.32 h, respectively. In muscle THA was eliminated more quickly than FLR. The peak concentrations of THA and FLR in the hepatopancreas were 204.25 and 164.22 μg/g, respectively, and the values for AUC_0-t were 1,337.74 and 871.73 mg/kg·h, respectively, which were much higher than those in hemolymph and muscle. The in vitro protein-binding value of THA (28.38%) was lower than that of FLR (37.91%), which might be related to the finding that THA in Pacific white shrimp was absorbed and eliminated more quickly than FLR.

Received July 21, 2012; accepted November 23, 2012

ACKNOWLEDGMENTS

This work was supported financially by the Special Fund for Agro-scientific Research in the Public Interest (200803012 and 201203085).