Detection and Quantitation of Lomefloxacin and Pefloxacin Residues in the Organ Tissues and Eggs of Laying Hens.

Lomefloxacin (LOM) and pefloxacin (PEF) are synthetic antibiotics that have been used in the treatment of infectious diseases in both human and animals. In the People's Republic of China, the use of LOM and PEF in livestock has been prohibited because of the concern that the residues of these drugs may pose a risk to public health. Despite this prohibition, these drugs are still being used in the poultry industry illegally, and so far there has been no systematic study of the persistence of LOM and PEF residues in chickens. In this study, laying hens were treated with a daily dose (10 mg/kg of body weight) of LOM or PEF for five consecutive days, and the drug residues in various tissues and eggs were determined over a 15-day period after the last drug administration. The highest LOM and PEF residual concentrations were found in the tissues 4 h after the last drug administration, and concentrations gradually decreased over time. Plasma had the lowest and liver had the highest residual concentrations throughout the 15-day study period. At the end of the 15 days, 3.64 ± 0.74 μg/kg LOM and 1.78 ± 0.28 μg/kg PEF were detected in the liver, with slightly lower residual concentrations in the kidney. No LOM or PEF residue was detected in the ovarian follicle, plasma, and muscle at the end of the 15 days. In eggs, the depletion rate of LOM was slower than that of PEF. LOM and PEF residues were detected in whole eggs for up to 10 and 8 days, respectively, after drug administration ceased. These findings suggest that the liver and, to a lesser extent, the kidney may be the sites where LOM or PEF residues would persist. This information can be a reliable reference for governmental agencies with respect to the screening of LOM and PEF residues in food products derived from laying hens.