Difloxacin Disposition and Residues in Broiler Chickens

Difloxacin disposition in broiler chickens was studied, with the objective of establishing pharmacokinetic parameters in plasma and tissues and estimating a withdrawal period. Forty-two adult chickens were divided into 14 groups of 3 individuals each, which received a 10 mg/kg single oral dose of difloxacin after a period of fasting between 12 hours before and 3 hours after administration. Each batch was sacrificed at pre-established times, and blood, muscle lung, liver, skin and kidney samples were obtained in a period up to 120 hours post application. Assay consisted in the extraction of the analyte, its separation and quantification by high performance liquid chromatography (HPLC). Mean plasma and tissue concentrations of difloxacin by time were analyzed with the PK Solution software. Oral application determines rapid absorption, moderate plasmatic permanence and extensive tissue distribution. The analysis of residual concentrations in tissues using WT 1.4 software calculated the withdrawal period, based on maximum residue limits (MRL) of 300, 1900, 400, 600 and 300 µg/kg, established for muscle, liver, skin, kidney and lung, respectively, a withdrawal period of 3 days is estimated for muscle, liver and skin and 5 days for kidney and lung.