title: The Analysis of Phenylbutazone and Its Active Metabolite, Oxyphenbutazone, in Equine Tissues (Muscle, Kidney, and Liver), Urine, and Serum by LC-MS/MS.
abstract: This study reports the use of two validated LC with tandem MS (MS/MS) methods to study the residue depletion profile of phenylbutazone (PBZ) and its metabolite oxyphenbutazone (OXPBZ) from equine serum, urine, and muscle, kidney, and liver tissues. One LC-MS/MS method, with an LOQ of 1.0 ng/mL for PBZ and 2.0 ng/mL for OXPBZ, was used for the analysis of the two drugs in the biological fluids (equine urine and serum); the other LC-MS/MS method, with an LOQ of 0.5 ng/g for PBZ and OXPBZ, was used for the analysis of the drugs in the equine tissue samples. PBZ was administered intravenously to two horses dosed with 8.8 mg/kg PBZ once daily for 4 days and sacrificed humanely at a slaughter plant 7 days after the last drug administration. Urine, serum, and kidney, liver, and muscle tissues were collected from the two horses and shipped on ice to the laboratory and stored at -20°C until analysis. The concentrations of PBZ and OXPBZ residues in the biological fluid and tissue samples collected at slaughter were measured with the two validated LC-MS/MS methods using deuterated internal standards. The results demonstrate that the validated methods are fit for studying the depletion kinetics of PBZ residues in equine tissues and biological fluids.
authors.affiliation: Canadian Food Inspection Agency, Centre for Veterinary Drug Residues, 116 Veterinary Rd, Saskatoon, SK S7N 2R3, Canada.
authors.forename: Joe O
authors.initials: JO
authors.lastname: Boison
authors.affiliation: University of Saskatchewan, Western College of Veterinary Medicine, Department of Veterinary Biomedical Sciences, Saskatoon, SK, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Dowling
authors.affiliation: Canadian Food Inspection Agency, Centre for Veterinary Drug Residues, Saskatoon, SK, Canada.
authors.forename: Johanna L
authors.initials: JL
authors.lastname: Matus
authors.affiliation: Canadian Food Inspection Agency, Centre for Veterinary Drug Residues, Saskatoon, SK, Canada.
authors.forename: Jana
authors.initials: J
authors.lastname: Kinar
authors.affiliation: University of Guelph, Ontario Veterinary College, Department of Biomedical Sciences, Guelph, ON, Canada.
authors.forename: Ron
authors.initials: R
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis*; D006736:Horses; D007668:Kidney; D008099:Liver; D009117:Muscidae; D010113:Oxyphenbutazone / Q000032:analysis*; D010653:Phenylbutazone / Q000032:analysis*; D044967:Serum; D053719:Tandem Mass Spectrometry; D019155:Veterinary Drugs / Q000032:analysis*
chemical_list: D019155:Veterinary Drugs; D010653:Phenylbutazone; D010113:Oxyphenbutazone