Elimination of aminoglycoside antibiotics in milk following intramammary administration.

The elimination in cow milk of aminoglycoside antibiotic residues (neomycin, dihydrostreptomycin, kanamycin and gentamicin) was studied after intramammary administration of eight drug formulations marketed in France. Quantitative residue analysis was performed by a cylinder plate method. The sensitivity was 0.15 microgram/ml for neomycin, dihydrostreptomycin, kanamycin and 0.025 microgram/ml for gentamicin. The mean elimination periods ranged between 4 and 13 milkings. Several ways of assessing withdrawal times are discussed.