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Title: ANALYSIS OF FENBENDAZOLE RESIDUES IN BOVINE MILK BY ELISA

Author
item Brandon, David
item Bates, Anne
item Binder, Ronald
item Montague Jr, William
item Whitehand, Linda
item BARKER, STEVEN - LOUISIANA STATE UNIV.

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2002
Publication Date: 9/6/2002
Citation: Brandon, D.L., Bates, A.H., Binder, R.G., Montague Jr., W.C., Whitehand, L.C., Barker, S.A. 2002. Analysis of fenbendazole residues in bovine milk by elisa. Journal of Agricultural and Food Chemistry. 50:5791-5796.

Interpretive Summary: This paper describes a method to test milk for residues of fenbendazole, an anti-worm drug, using 2 monoclonal antibody-based assays. The assays indicated that residue levels varied widely among individual cows in each group. Fenbendazole levels peaked at about 12 - 24 h and metabolite levels peaked at 24 - 36 h. All residue levels were undetectable by 72 h. The ELISA method could be used to flag high-residue samples in on-site monitoring of fenbendazole in milk and is a potential tool for studying drug pharmacokinetics.

Technical Abstract: Fenbendazole residues in bovine milk were analyzed by ELISAs, using two monoclonal antibodies. One monoclonal antibody (MAb 587) bound the major benzimidazole anthelmintic drugs, including fenbendazole, oxfendazole, and fenbendazole sulfone. The other (MAb 591) was more specific for fenbendazole, with 13% cross-reactivity with the sulfone and no significant binding to the sulfoxide metabolite. The limit of detection of the ELISA method in the milk matrix was 7 ppb for MAb 587 and 3 ppb for MAb 591. Fenbendazole was administered in feed, drench, and paste form to three groups of dairy cattle. Milk was collected immediately before dosing and then every 12 h for 5 days. The ELISA indicated that residue levels varied widely among individual cows in each group. Fenbendazole levels peaked at about 12 - 24 h and declined rapidly thereafter. Metabolites were detected at much higher levels than the parent compound, peaked at about 24 - 36 h, and declined gradually. Residue levels were undetectable by 72 h. The ELISA data correlated well with the total residues determined by chromatographic analysis, but the use of the two separate ELISAs did not afford an advantage over ELISA with the single, broadly reactive MAb 587. The ELISA method could be used to flag high-residue samples in on-site monitoring of fenbendazole in milk and is a potential tool for studying drug pharmacokinetics.