Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2004
Publication Date: August 22, 2004
Citation: Smith, D.J., Huwe, J.K., Lorentzsen, M.K., Harrington, G.E. 2004. Biotransformation of [14c]-phenylbutazone after oral or intravenous administration to cattle. [abstract] American Chemical Society National Meeting, Philadelphia, PA, 8/22-26/2004, Picogram No. 67, Abstract No. 124. Technical Abstract: Phenylbutazone (PBZ) is a non-steroidal anti-inflammatory agent that is sometimes used in an off-label manner by livestock producers. No withdrawal period has been established for phenylbutazone and no marker compound or tissue exists for PBZ in cattle. The objective of this study was to identify PBZ metabolites in cattle and to determine the identity of PBZ related residues in tissues. Urine samples were filtered, chromatographed, and metabolites analyzed by quadrapole time-of-flight MS. Tissue residues were extracted prior to analysis. Parent phenylbutazone was the major excretory product in cattle urine. Two ring-hydroxylated (phenolic) and three metabolites hydroxylated on the butyl alkyl group were detected as were three metabolites containing dual sites of oxidation. An O-glucuronide of a mono-hydroxylated metabolite and a C-glucuronide of parent PBZ were excreted in the urine. Approximately 20 and 30% of the liver and kidney residues, respectively, were non-extractable radiocarbon; phenylbutazone was present in the extracts.