Pharmacokinetics, optimal dosages and withdrawal time of florfenicol in Asian seabass (Lates calcarifer) after oral administration via medicated feed

A Green HPLC Approach to Florfenicol Analysis in Pig Urine

Florfenicol (FF) is a broad-spectrum antibiotic used to treat gastrointestinal and respiratory infections in domestic animals. Considering FF's rapid elimination via urine after drug treatment, its use increases concerns about environmental contamination. The objective of the study was to establish a sustainable chromatographic method for simple analysis of FF in pig urine to investigate the urinary excretion of FF after a single intramuscular administration of 20 mg FF/kg body weight. The urine sample was prepared using a centrifuge and regenerated cellulose filter, and the diluted sample was analyzed. The method was validated in terms of linearity, the limit of detection (0.005 µg/mL) and quantitation (0.016 µg/mL), repeatability and matrix effect (%RSD ranged up to 2.5), accuracy (varied between 98% and 102%), and stability. The concentration-time profile of pig urine samples collected within 48 h post-drug administration showed that 63% of FF's dose was excreted. The developed method and previously published methods used to qualify FF in the urine of animal origin were evaluated by the National Environmental Method Index (NEMI), Green Analytical Procedure Index (GAPI) and Analytical GREENness Metric Approach (AGREE). The greenness profiles of published methods revealed problems with high solvents and energy consumption, while the established method was shown to be more environmentally friendly.

Pharmacokinetics and tissue distribution of florfenicol and florfenicol amine in snubnose pompano (Trachinotus blochii) following oral administration

The present study reports the comparative pharmacokinetic profiles of florfenicol and its metabolite (florfenicol amine, FFA) in Trachinotus blochii under tropical marine conditions (salinity: 35 ± 1.4‰; temperature: 28.8 ± 0.54 °C) following a single in-feed oral administration of the recommended dose (15 mg/Kg). Furthermore, the study investigated the distribution of these two compounds in nine different tissues. The maximum florfenicol concentrations (C_max) in plasma and tissues were observed within five hours (T_max), except for bile. The C_max ranged from 572 to 1954 ng/g or ml and was in the intestine > bile > muscle + skin > liver > gill = heart > plasma > kidney = spleen. The elimination half-life of FFC was significantly slower in the bile (38.25 ± 4.46 h). The AUC tissue/plasma was highest for bile (3.77 ± 0.22), followed by intestine > muscle + skin > heart > liver > kidney = gill = spleen. T_max and t_1/2β were slower, and C_max was lower for FFA than florfenicol in all tissues except C_max of the kidney and bile. FFA t_1/2β was exceptionally slower in the kidney (46.01 ± 8.2 h). Interestingly, reaching an apparent distribution rate of > 0.5 was comparatively faster in the kidney, liver, and gills than in other tissues. The highest apparent metabolic rate was in the kidney (0.95 ± 0.01) and the lowest in plasma (0.41 ± 0.01). The generated data can be applied for formulating efficient therapeutic protocols in T. blochii, a promising mariculture species.

Effects of temperature on the pharmacokinetics, optimal dosage, tissue residue, and withdrawal time of florfenicol in asian seabass (lates calcarifer)

Drug behavior in the bodies of fish is largely influenced by the water temperature. Antimicrobial drugs are needed for the control of bacterial outbreaks in farmed fish including Asian seabass (Lates calcarifer). However, little is known about the temperature effect on appropriate drug uses in this species. The purpose of this study was to investigate the differences in pharmacokinetics (PK), optimal dosages, tissue depletion, and withdrawal time (WDT) of florfenicol (FF) in Asian seabass reared at 25 and 30 °C. In the PK study, the fish were administered with a single oral dose of 10 mg/kg FF. The optimal dosing regimen was determined by the pharmacokinetic-pharmacodynamic (PK-PD) approach. In the tissue depletion and WDT study, FF was administered at the optimal dosages once daily for 5 days and the WDT was determined by linear regression analysis based on the sum of FF and its metabolite florfenicol amine (FFA) in the muscle/skin. When the temperature was increased from 25 to 30 °C, the elimination half-life of FF was significantly decreased from 11.0 to 7.2 h. While the other PK parameters were not changed significantly, the calculated optimal dosages for the target minimum inhibitory concentration (MIC) of 2 µg/mL were 10.9 and 22.0 mg/kg/day, respectively for 25 and 30 °C. The sum of FF + FFA is a preferable marker residue for WDT determination because differential FF metabolism was observed at different temperatures. The depletion half-life of the muscle/skin was shortened from 41.1 to 32.4 h by the 5 °C temperature increase. Despite different absolute amounts of FF given between the two temperature levels, the WDTs were very similar at 6-7 days. Thus, it appears that a single temperature-independent WDT can potentially be assigned when the drug was applied at the optimal dosage.