Residues of Albendazole and Metabolites in Eggs from Treated Laying Hens

BISTOLETTI, M.; ALVAREZ, L.; LANUSSE, C.; MORENO, L.

Congreso; 12th International Congress of The European Association for Veterinary Pharmacology & Toxicology (EAVPT); 2012

Introduction: Benzimidazole (BZD) anthelmintics are widely used in veterinary medicine. They have broad spectrum, being effective against gastrointestinal roundworms, gapeworms and tapeworms. Endoparasites are a common and frequently underestimated problem in avian farms (Tucker, 2007). Flubendazole (FLBZ) is the unique BZD licensed for used in poultry. However, it is well known that other BZD compounds, such as albendazole (ABZ), are currently extra-labelled used in avian production systems. The pharmacokinetic behaviour and tissue residue depletion for these anthelmintics are well established in ruminant species. However, the available information on BZD kinetics and tissue residue profiles in poultry is scarce. The aim of the current work was to characterise the residual concentrations of ABZ and its sulphoxide (ABZSO) and sulphone (ABZSO2) metabolites in eggs after ABZ treatment to laying hens. Materials and Methods: Eight (8) Plymouth Rock Barrada laying hens were treated with ABZ (10 mg/kg/day) in food over seven days. The produced eggs were collected during 10 days after treatment. Eggs were processed (chemical extraction) and analyzed by HPLC (Bistoletti, 2011) to measure ABZ/ metabolites residual concentrations. Results: ABZ, ABZSO and ABZSO2 residual concentrations were quantified in eggs from 2 up to 10 days after starting the ABZ treatment. The highest egg residual level was measured for ABZSO2 with a maximum concentration (1.35±0.01 µg/g) at day 7 after start treatment. Meanwhile the maximum egg residual concentrations for ABZ and ABZSO (also at day 7 after start treatment) were 1.03±0.01 and 0.57±0.01 µg/g, respectively. The area under the curve values (AUC) estimated as the total residue exposure in egg were 100.5 (ABZ), 56.3 (ABZSO) and 141.3 µg·h/g (ABZSO2). Conclusions: Residual concentrations of ABZ and its metabolites were measured in eggs after its administration in food to laying hens. There is not data available of Maximum Residue Limits (MRLs) for ABZ in eggs. However, taking as reference the MRL established for FLBZ in eggs (400 µg/kg) (EMEA, 2006), higher egg residue levels were found in the present work. Therefore, before a therapeutic ABZ use is recommended, appropriate MRLs should be established to estimate adequate withdrawal times to avoid any risk for human health associated with consumption of drug residues in eggs. The work reported here contributes with data on residual concentration profiles useful to assure a proper use of ABZ in laying hens.