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Distribution of Animal Drugs between Skim Milk and Milk Fat Fractions in Spiked Whole Milk: Understanding the Potential Impact on Commercial Milk Products

Heldur Hakk, Nancy W. Shappell, Sara J. Lupton, Weilin L. Shelver, Wendy Fanaselle, David Oryang, Chi Yuen Yeung, Karin Hoelzer, Yingqing Ma, Dennis Gaalswyk, Regis Pouillot, Jane M. Van Doren
Journal of agricultural and food chemistry 2016 v.64 no.1 pp. 326-335
benzylpenicillin, animals, data collection, drug residues, erythromycin, food contamination, hydrophobicity, ionization, ivermectin, ketoprofen, milk fat, models, oxytetracycline, skim milk, sulfadimethoxine, thiabendazole, whole milk
Seven animal drugs [penicillin G (PENG), sulfadimethoxine (SDMX), oxytetracycline (OTET), erythromycin (ERY), ketoprofen (KETO), thiabendazole (THIA), and ivermectin (IVR)] were used to evaluate the drug distribution between milk fat and skim milk fractions of cow milk. More than 90% of the radioactivity was distributed into the skim milk fraction for ERY, KETO, OTET, PENG, and SDMX, approximately 80% for THIA, and 13% for IVR. The distribution of drug between milk fat and skim milk fractions was significantly correlated to the drug’s lipophilicity (partition coefficient, log P, or distribution coefficient, log D, which includes ionization). Data were fit with linear mixed effects models; the best fit was obtained within this data set with log D versus observed drug distribution ratios. These candidate empirical models serve for assisting to predict the distribution and concentration of these drugs in a variety of milk and milk products.