Amduca and Extra-Label Drug Use: Rights and Responsibilities for the Zoo and Wildlife Veterinarian
American Association of Zoo Veterinarians Conference 1997
Linda Wilmot, DVM, MS
Center for Veterinary Medicine, Food and Drug Administration, Rockville, MD, USA


Prior to October 1994, section 512 of the Federal Food, Drug, and Cosmetic Act provided that a new animal drug (NAD) was deemed unsafe unless it was subject to an approved application and the drug, its labeling and its use conformed to such approved application. Therefore, use of a new animal drug without an approved application or in a manner different from that set forth in an approved application resulted in the drug being unsafe under this act. The Animal Medicinal Drug Use Clarification Act (AMDUCA) for which regulations were published in the Federal Register in November 1996 and for which implementing regulations took effect in December 1996, allows veterinarians to prescribe extra-label uses of FDA-approved animal drugs and approved human drugs for animals.

Zoo species and free-ranging wildlife species which are not harvested for human food fall into the non-food animal arena; therefore, the AMDUCA allows veterinarians to use whatever drug (approved human or animal) they need to effectively practice. Extra-label use (ELU) of an approved human or animal drug is permitted when there is no animal drug approved for the intended use; when there is an animal drug approved for the intended use, but the approved drug is not in the required dosage form or concentration; or when an approved drug has been found to be clinically ineffective when used as labeled. Furthermore, when the intended use involves administration to a nonfood animal, an approved human drug can be used.

Free-roaming wildlife species which may be hunted are viewed differently. The agency understands that some of these animals may be harvested for human food, and, therefore, they are considered to be food animals. When considering ELU in these animals, veterinarians must be in conformity with the provisions of the regulations applicable to food animals.

In food animals the “first resort” for ELU is an approved animal drug rather than an approved human drug. ELU that doesn’t require compounding is the “first resort” over ELU that does. When compounding is appropriate for use in food animals, “first resort” is to an approved animal drug rather than an approved human drug. All other requirements of the regulations must also be met (e.g., adequate record keeping, appropriate withdrawal time, etc.). For example, certain drugs are prohibited for use in food animals. These include chloramphenicol, clenbuterol, diethylstilbestrol, dimetridazole, ipronidazole, other nitroimidazoles, furazolidone (except for approved topical use), nitrofurazone (except for approved topical use), and sulfonamide drugs in lactating dairy cattle (except approved use of sulfadimethoxine, sulfabromomethazine, and sulfamethoxypyridazine).

Fluoroquinolones and glycopeptides are in the process of being added to the list of prohibited drugs.

In addition, the timing of ELU should take into consideration periods of harvest (e.g., hunting seasons). Determination of an appropriate withdrawal time is the responsibility of the veterinarian, taking into account the species, their range, published withdrawal times in approved species, and local hunting seasons.

The agency believes that Congress intended that veterinarians be responsible for overseeing the extra-label use of drugs. The agency recognizes the unique applicability of the veterinary-client-patient (VCP) relationship to free-ranging wildlife. With respect to use of drugs by non-veterinarians, such as wildlife biologists who are typically state or Federal employees, it is noted that they are usually under the general supervision of a veterinarian, who may also be a government employee. Such relationships fall within the scope of a valid VCP relationship.

The preceding comments are general. There are limitations in the AMDUCA prohibiting extra-label use of certain drugs under specific conditions and other special circumstances. Interested parties are encouraged to contact the Center for Veterinary Medicine for further information.


Speaker Information
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Linda Wilmot, DVM, MS
Center for Veterinary Medicine
Food and Drug Administration
Rockville, MD, USA

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