Oxytetracycline tolerances

Following intramuscular injection of a long-acting oxytetracycline formulation, all sheep tissue residues were below the US tolerance of 0.1 ppm by 14 days after treatment (235). After intramuscular administration to a dairy cow of a single dose of 5 mg oxytetracycline/kg bw, residues were present in milk for as long as 4 days after dosing at concentrations ranging from 370 ppb at day 1 posttreatment to 10 ppb at day 4 posttreatment (233). 

Oxytetracycline is also one of the most frequently used antibiotics in fish farming. Oxytetracycline residues exceeding the 0.1 ppm tolerance level were detected in raw catfish fillets 18 h after oral administration at a dosage of 37.5, 75, or 150 mg/kg fish for 10 days (238). Residues were highest in liver, followed by muscle, plasma, and kidney. Drug excretion was temperature dependent higher residue levels could be detected at lower temperatures. In rainbow trout... 

Banting, A. de L. Baggot, J.D. (1996) Comparison of the pharmacokinetics and local tolerance of three injectable oxytetracycline formulations in pigs. Journal of Veterinary Pharmacology and Therapeutics, 19, 50-55. 

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