Submitted to: Journal of Food Additives & Contaminants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2004
Publication Date: 6/15/2004
Citation: Shaikh, B., Rummel, N., Smith, D.J. 2004. Determination of 14C residue in eggs of laying hens administered orally with [14C]sulfaquinoxaline. Journal of Food Additives & Contaminants. 21:545-554.
Interpretive Summary: Sulfonamide drugs are widely used in poultry for the clinical treatment of bacterial diseases and for incorporation into feeds at subtherapeutic levels to promote growth. Sulfaquinoxaline (SQX) is approved for use in broiler chicks for the prevention and treatment of various bacterial diseases, but not for use in laying hens. Under the Animal Medicinal Drug Use Clarification Act, veterinarians under certain conditions are allowed to prescribe certain FDA-approved animal and human drugs for extralabel use in animals. However, because of the widespread use and availability of these drugs for use in poultry and other species, their unapproved use is a possibility and such use may result in violative residues in eggs and other edible products. The objective of this study was to investigate the transfer of SQX in eggs and to determine its residue levels in both egg albumen and yolk. The results of this study indicate that SQX remains in egg yolks longer than in albumen; as a result, regulatory agencies should use egg yolk in assays investigating the off-label or illegal use of SQX in laying hens.
Technical Abstract: Ten layer hens were orally dosed for five consecutive days with 6.2 mg/kg of [14C]sulfaquinoxaline (SQX). Eggs were collected from the hens during the five-day dosing period and during a 10-day post dose withdrawal period. Egg yolk and albumen were separated and assayed for total radioactive residues (TRR) using a combustion oxidizer and liquid scintillation counting techniques. Significant amounts of radioactivity were detected on the second day of dosing (greater than 24 hours after the initial dose) in both egg yolk and albumen. Radioactive residues reached a maximum on the fifth day of dosing in albumen and on the second day of withdrawal in egg yolk. The peak TRR levels in albumen were about three-fold higher than in yolk. Thereafter, the TRR levels declined rapidly in albumen and were depleted by withdrawal day six. TRR levels in egg yolks declined more slowly and were depleted by withdrawal day ten. The HPLC analysis indicated that the parent drug sulfaquinoxaline was the major component in both the egg albumen and yolk. Furthermore, this work suggests that egg yolk is the appropriate matrix for monitoring SQX residues.