title: Pharmacokinetics and tissue elimination of flunixin in veal calves.
abstract: OBJECTIVE To describe plasma pharmacokinetic parameters and tissue elimination of flunixin in veal calves. ANIMALS 20 unweaned Holstein calves between 3 and 6 weeks old. PROCEDURES Each calf received flunixin (2.2 mg/kg, IV, q 24 h) for 3 days. Blood samples were collected from all calves before the first dose and at predetermined times after the first and last doses. Beginning 24 hours after injection of the last dose, 4 calves were euthanized each day for 5 days. Plasma and tissue samples were analyzed by ultraperformance liquid chromatography. Pharmacokinetic parameters were calculated by compartmental and noncompartmental methods. RESULTS Mean ± SD plasma flunixin elimination half-life, residence time, and clearance were 1.32 ± 0.94 hours, 12.54 ± 10.96 hours, and 64.6 ± 40.7 mL/h/kg, respectively. Mean hepatic and muscle flunixin concentrations decreased to below FDA-established tolerance limits (0.125 and 0.025 μg/mL, respectively) for adult cattle by 3 and 2 days, respectively, after injection of the last dose of flunixin. Detectable flunixin concentrations were present in both the liver and muscle for at least 5 days after injection of the last dose. CONCLUSIONS AND CLINICAL RELEVANCE The labeled slaughter withdrawal interval for flunixin in adult cattle is 4 days. Because administration of flunixin to veal calves represents extralabel drug use, any detectable flunixin concentrations in edible tissues are considered a violation. Results indicated that a slaughter withdrawal interval of several weeks may be necessary to ensure that violative tissue residues of flunixin are not detected in veal calves treated with that drug.
authors.forename: Lindsey W
authors.initials: LW
authors.lastname: Kissell
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Brinson
authors.forename: Ronette
authors.initials: R
authors.lastname: Gehring
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Tell
authors.forename: Scott E
authors.initials: SE
authors.lastname: Wetzlich
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Baynes
authors.forename: Jim E
authors.initials: JE
authors.lastname: Riviere
authors.forename: Geof W
authors.initials: GW
authors.lastname: Smith
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002417:Cattle / Q000097:blood*; D003002:Clonixin / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D004350:Drug Residues; D006207:Half-Life; D008099:Liver / Q000737:chemistry; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; C014557:flunixin; D003002:Clonixin