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Reduced Resident Time and Tissue Residues of Synergistic Florfenicol-Thiamphenicol Combination in Leghorn Chickens
Tirawat Rairat1, Ming-Kun Hsieh2, Thomas W. Vickroy3 and Chi-Chung Chou1,*
1Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan; 2Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan; 3Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32610; *Corresponding author:


In vivo synergistic antimicrobial effects against pathogens in chickens have been reported for florfenicol (FF) and thiamphenicol (TAP) at a ratio of 1:2. The present study evaluates the pharmacokinetics and tissue residues of a single combined intramuscular treatment of FF+TAP at 1/6 and 1/3 of their respective recommended doses in 5-week old broiler chickens. The drug concentrations were determined by LC/MS/MS. Significant reductions were observed in the Cmax (0.045 and 2.64 µg/mL for FF and TAP, respectively) and AUC (0.13 and 7.19 h∙µg/mL for FF and TAP, respectively) compared to corresponding values reported for the recommended dose (up to two orders of magnitude lower). Tissue FF (10.6-88.4 µg/kg) and TAP concentrations (6.5-147.0 µg/kg) declined below the maximum residue limit within only one day except for TAP residue in skin/fat. This experiment provided supporting evidence for a complete study that synergistic FF-TAP has potential benefits over monotherapy since drug residues could be greatly reduced; much shorter withdrawal period was strongly indicated.

To Cite This Article: Rairat T, Hsieh MK, Vickroy TW and Chou CC, 2019. Reduced resident time and tissue residues of synergistic florfenicol-thiamphenicol combination in Leghorn chickens. Pak Vet J, 39(2): 310-312.


ISSN 0253-8318 (Print)
ISSN 2074-7764 (Online)