Tissue Distribution and Residues of Antibiotics in Normal and Emergency — Slaughtered Dairy Cows After Intramammary Treatment

Abstract

Following intramammary infusion of normal cows with a single dry cow and four lactating-cow antibiotic formulations containing penicillin G, neomycin, dihydro-streptomycin, lincomycin and framycetin, low concentrations of drug residues were detected in the kidney, urine, and for some drugs, also in blood and the liver, during the first 24 h after treatment. Drug residues were not detected in meat. In emergency-slaughtered mastitic cows, drug levels were considerably higher and persisted for a longer period than in normal cows. Persistence of drug residues is discussed in terms of the rate and extent of drug absorption from the udder, differences between normal and diseased cows, and effect of dosage form.

Human Food Safety Implications of Variation in Food Animal Drug Metabolism

“…The influence of diseases on the disposition of veterinary drugs and the resulting consequences on withdrawal time has been acknowledged for several decades8. The strength of the present study is to provide a broader-based quantitative estimate of the magnitude of this effect based on PBPK model simulations involving multiple veterinary drugs in two commonly used food animal species.…”

Effect of injection site on the bioavailability of an oxytetracycline formulation in ruminant calves

“…The disposition of oxytetracycline (OTC) is influenced by dosage, route of administration, absorption characteristics and bioavailability of the formulation involved (1, 4,6,7,10,11,13,16,17), disease state (2,8,9) and age of the patient (12). Recently the effect of the injection site in the case of aminopenicillins on the bioavailability and pharmacokinetics were studied in normal animals (5,14,15) and in animals with endotoxin-induced fever (3).…”

Comparative plasma ampicillin levels and bioavailability of five parenteral ampicillin formulations in ruminant calves

“…In the suggested pre-slaughter withdrawal times (Table 5) a safety factor of at least two was introduced for diseased calves. This is because absorption and elimination rates may be decreased in diseased animals, resulting in increased drug persistence in tissues (13). In nephritic animals the suggested withdrawal time might be five times longer than that calculated for normal animals (14).…”

“…Albipen® and Duphacillin®) may persist for weeks at the injection site, whilst ampicillin residues are not detected in other parts of the body. The impact of drug residues at the injection site is discussed elsewhere (13). Thus for presenting the choice of drugs to the practitioner, both pharmacokinetic and clinical data should be part of label directions.…”