Depletion, metabolism, and risk assessment of clopidol in broilers

The anticoccidial agents clopidol is widely used in livestock production to prevent coccidiosis; however, the residues that remain in edible tissues pose a risk to human consumers. This study investigated the residue depletion and metabolism of orally administered radiolabeled [³H]-clopidol (25 mg/kg body weight) in the liver, muscle, kidney, and fat. The analytical methods employed for all tissues were subjected to rigorous validation to ensure their selectivity, linearity (r² ≥ 0.999), system suitability (0.4%), accuracy (89.5-102.5%), and precision (> 5.2%). The validated method using radio-HPLC and liquid scintillation counting indicated that the highest concentrations of clopidol residues were observed 6 h post-administration in the liver (28.81 ± 2.41 mg/kg), muscle (14.31 ± 0.77 mg/kg), kidney (29.22 ± 2.3 mg/kg), and fat (7.26 ± 0.70 mg/kg). Most clopidol levels subsequently decreased and were below the limit of quantification after 3 d in all tissues. The metabolite 3,5-dichloro-2-hydroxymethyl-6-methylpyridin-4-ol was detected in all tissues 6 h after administration using LC-MS (liver: 1.17 ± 0.29 mg/kg, muscle: 0.73 ± 0.15 mg/kg, kidney: 2.76 ± 1.03 mg/kg, and fat: 0.5 ± 0.11 mg/kg). A health risk assessment indicated that the residual concentrations in edible tissues were safe for consumption by all ages and sexes. This study provides a useful framework for monitoring clopidol residues, their depletion, and metabolism in broiler chickens and the by-products.