title: Residue depletion in tissues and fluids from swine fed sulfamethazine, chlortetracycline and penicillin G in combination.
abstract: Twenty-four hogs were fed a ration for 14 days containing three times the recommended label dose of a combination drug which included sulfamethazine, chlortetracycline and penicillin G. Groups of six hogs were slaughtered 0, 2, 4, or 8 days after withdrawal. Six untreated control hogs were slaughtered 5 days before the first group, of six treated hogs, were slaughtered. Residue concentrations were determined in kidney, liver, muscle, serum and urine. At zero withdrawal the kidney from one hog contained 0.018 mg penicillin G per kg and the serum from the same hog contained 0.016 mg penicillin G per litre. Penicillin G was not detected in any other samples that were analysed. Chlortetracycline concentrations in tissues at zero withdrawal time were below accepted Canadian Maximum Residue Limits (MRL) for chlortetracycline of 1 mg/kg in muscle, 2 mg/kg in liver and 4 mg/kg in kidney and were below the limit of quantitation in all tissues 4 days after withdrawal. Sulfamethazine persisted in the tissues longer than penicillin G or chlortetracycline. Sulfamethazine concentrations were above the Canadian MRL of 0.1 mg/kg at zero withdrawal time and did not decrease to below the MRL until 8 days after withdrawal. Our results suggest that, if the label withdrawal period of 10 days is observed, an increase in the dosage of up to three times the recommended rate is unlikely to increase significantly the risk that residues would occur in the tissues of treated hogs at concentrations which exceed MRLs. Sulfamethazine concentrations in all matrices decreased after storage at -76 degrees C for 6 months.
authors.affiliation: Health of Animals Laboratory, Agriculture and Agri-Food Canada, Saskatoon, Saskatchewan, Canada.
authors.forename: G O
authors.initials: GO
authors.lastname: Korsrud
authors.forename: M G
authors.initials: MG
authors.lastname: Papich
authors.forename: A C
authors.initials: AC
authors.lastname: Fesser
authors.forename: C D
authors.initials: CD
authors.lastname: Salisbury
authors.forename: J D
authors.initials: JD
authors.lastname: MacNeil
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002751:Chlortetracycline / Q000032:analysis* / Q000493:pharmacokinetics; D004350:Drug Residues / Q000032:analysis*; D005260:Female; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008297:Male; D009132:Muscles / Q000737:chemistry; D009919:Orchiectomy; D010400:Penicillin G / Q000032:analysis* / Q000493:pharmacokinetics; D010406:Penicillins; D013418:Sulfamethazine / Q000032:analysis* / Q000493:pharmacokinetics; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D010406:Penicillins; D013418:Sulfamethazine; D010400:Penicillin G; D002751:Chlortetracycline