Food safety evaluation for the use of albendazole in fish: residual depletion profile and withdrawal period estimation

Due to the lack of drugs regulated for aquaculture, we have evaluated the use of albendazole (ABZ)–a potential drug to be regulated for fish–under food safety perspectives assessing the depletion profile of ABZ and its main metabolites (albendazole sulphoxide–ABZSO, albendazole sulphone–ABZSO₂ and albendazole amino sulphone–ABZ-2-NH₂SO₂) in fish fillets (muscle and skin) after single dose oral administration of 10 mg ABZ kg^-1 body weight. For the drug administration, a suitable procedure for ABZ incorporation into fish feed was employed, obtaining good homogeneity of ABZ concentration among feed pellets (CV<4.1%) and low drug leaching when medicated feed remained in the water for up to 60 min (<2.7%). After medication, fish were euthanised at 8, 12, 24, 48, 72, 96 and 120 h and fillets collected. Depletion studies in various fish species (patinga and tilapia) were conducted simultaneously, under water temperature at 30.4 ± 0.3 °C and pH 6.8 ± 0.1. The highest concentrations for the sum of residues (ABZ, ABZSO, ABZSO₂ and ABZ-2-NH₂SO₂) in fish fillet were 1210 ng g^-1 in patinga and 637 ng g⁻¹ in tilapia. Under the employed rearing conditions, the obtained results did not indicate a requirement for a minimum withdrawal period to be proposed for tilapia considering the maximum residue limit of 100 µg g⁻¹, since the determined residual concentration was <LOQ (10 ng g⁻¹) from 24 h post medication treatment. For patinga, the estimated minimum withdrawal period was 3 days. With the well-recognised demands for new alternative veterinary drugs for aquaculture use by fish farmers, this study offers important evidence for consideration of ABZ use in tilapia and patinga taking into account food safety issues.