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U.S. Department of Health and Human Services

Animal & Veterinary

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Reminder -- Extra-Label Use of Sulfonamides in Lactating Dairy Cattle Prohibited

August 19, 2005

FDA's Center for Veterinary Medicine (CVM) would like to remind veterinarians that extra-label use of sulfonamides in lactating dairy cattle is prohibited.  CVM has received some information indicating that sulfonamides, some in combination with trimethoprim, are being prescribed for use in treating conditions in lactating dairy cattle for which they are not approved.  The unapproved use of sulfonamides is one of the most frequent causes of violative residues in food-producing animals. 

The prohibition against extra-label use of sulfonamides in lactating dairy cattle is based on a finding by CVM that the extra-label use of these drugs presents a risk to the public health for the purposes of the Animal Medicinal Drug Use Clarification Act (AMDUCA) of 1994.  These extra-label uses are capable of causing violative residues of the drugs in milk and meat

The Animal Medicinal Drug Use Clarification Act (AMDUCA) amended the Federal Food, Drug, and Cosmetic Act to allow licensed veterinarians to prescribe extra-label uses of approved animal drugs and human drugs in animals. Section 530.25(a)(2) of the AMDUCA provides that the Agency may prohibit an extra-label drug use in food producing animals if, after affording an opportunity for public comment, the Agency finds that such use presents a risk to the public health.

The following drugs (both animal and human formulations), families of drugs, and substances are prohibited for extra-label uses in all food-producing animals:

  • Chloramphenicol;

  • Clenbuterol;

  • Diethylstilbestrol (DES);

  • Dimetridazole;

  • Furazolidone, Nitrofurazone, other nitrofurans;

  • Fluoroquinolones;

  • Glycopeptide;

  • Ipronidazole;

  • Other nitroimidazoles;

  • Phenylbutazone animal and human drugs in female dairy cattle 20 months of age or older; and 

  • Sulfonamide drugs in lactating dairy cattle (except approved use of sulfadimethoxine, sulfabromomethazine, and sulfaethoxypyridazine).

Currently sulfadimethoxine is the only marketed sulfonamide with approved formulations for lactating dairy cattle.  Products on the list of prohibited drugs may only be used according to the approved indications for use in their labeling.  Some formulations are not specifically approved for lactating dairy cattle.  Some of the prohibited drugs are approved for one class of food animal but not in others.  Veterinarians should read the label closely.

Veterinarians who have questions about AMDUCA or the extra-label use of drugs may contact FDA/CVM Division of Compliance, 7519 Standish Place, HFV-230, Rockville, MD 20855, Phone number (240) 276-9200.


Contact FDA

240-276-9115 FAX
Issued by: FDA, Center for Veterinary Medicine

Communications Staff, HFV-12

7519 Standish Place

Rockville, MD 20855