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U.S. Department of Health and Human Services

Animal & Veterinary

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CVM RESEARCH SCIENTISTS INVESTIGATE A UNIQUE ANIMAL MODEL

FDA Veterinarian Newsletter July/August 2000 Volume XV, No IV

By Pamela Chamberlain, D.V.M, D.A.B.T.

What do a pregnant Holstein dairy cow and a pregnant human have in common? No, this is not the opening line to a bad joke, but a very serious question being investigated by researchers in CVM’s Office of Research (OR) in Laurel, MD. The research team of Dr. Jurgen von Bredow, Dr. Pamela Chamberlain and Dr. Jim Peggins is studying the feasibility of using the dairy cow and her calf as a model for drug transfer from the dam to the neonate during the perinatal period. The model is being developed to address human as well as veterinary drug residue issues. Analytical method support for this research is being provided by OR’s Division of Residue Chemistry methods development program for veterinary drugs.

The model is designed to assess both transplacental and milk transfer of drugs to the offspring following treatment of the pregnant dam with therapeutic doses of a specific drug. The model allows a very detailed and comprehensive assessment of offspring exposure through intensive blood and milk sampling of the dam and the offspring throughout the exposure and post-exposure periods. A more accurate assessment of exposure will facilitate a more accurate assessment of potential risk. The goal is to show that the cow-calf model can provide better perinatal exposure assessments than currently available methods. These methods include use of small animal and mathematical models and limited data obtainable from humans.

Possible applications for the model include: the testing of important drugs not currently used to treat women during late pregnancy or lactation due to known toxicity and/or because of uncertain neonatal exposure potential. These could include antimicrobials, antihypertensives, antiepileptics, antidepressants or drugs prescribed to treat allergies. The model may also be useful for comparing residue levels in veal calves resulting from direct treatment of the calf versus those resulting from inadvertent exposures to drugs found in cow’s milk. This information could prove helpful for settling disputes regarding how a violative residue might have occurred.

The team has completed testing of two drugs in the model system. The results have attracted interest and support from the FDA’s Office of Women’s Health (OWH). Through the intramural research grant program, the OWH has agreed to fund additional development of the model to evaluate drugs of specific interest to women’s health.