Animal Medicinal Drug Use Clarification Act (AMDUCA)

The Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA) was promulgated by the U.S. Food and Drug Administration (FDA) to provide greater prescribing and dispensing options for veterinarians acting within a valid veterinarian-client-patient relationship (VCPR), so that animals can receive the medications they need when they need them and be more readily relieved of suffering. This legislation represented an important advancement for the veterinary profession, given the relatively few numbers of drugs approved by the FDA for use in animals.

Before the AMDUCA was passed, it was illegal to use an FDA-approved drug in a manner that differed in any way from the drug's approved labeling. The Federal Food, Drug, and Cosmetic Act had provided that a new animal drug was deemed unsafe unless it was subject to the FDA's stringent approval process—for exactly what was on the label, including the specific species, disease indication, dose, duration, frequency, and route of administration. The AMDUCA amended the Federal Food, Drug, and Cosmetic Act to legalize such “extralabel drug use” (ELDU) under a valid veterinarian-client-patient relationship (VCPR), as well as certain other conditions describing requirements for use, record keeping, and labeling according to FDA regulations.

ELDU includes deviations from FDA-approved labeling such as using the drug in any of the following ways:

  • In a species not listed on the label
  • For an indication not listed on the label
  • At a different dose or frequency than listed on the label
  • Via a different route of administration than listed on the label

Conditions for ELDU

Regulations concerning ELDU are covered in Title 21 Part 530 of the Code of Federal Regulations (21 CFR 530). ELDU covers not just FDA-approved animal drugs and human prescription drugs but also FDA-approved human over-the-counter products and preparations compounded from FDA approved products. The specific conditions under which extralabel use is permitted from compounding of approved animal or human drugs are found in 21 CFR §530.13.

  • The AMDUCA allows ELDU only on the lawful order of a licensed veterinarian in the context of a valid VCPR.
  • ELDU is limited to circumstances when the health of an animal is threatened, or failure to treat may result in the animal’s suffering or death. This means that extralabel use to enhance production is not permitted.

One of the following criteria also must be met:

  • No approved animal drug is available for the intended use.
  • An approved animal drug is available for the intended use, but:
    • That drug does not contain the needed active ingredient.
    • That drug is unavailable in the needed dosage form
    • That drug is unavailable in the required concentration.
    • The veterinarian has found, within the context of a valid VCPR, that the drug is clinically ineffective when used as labeled.

Beyond these general conditions, the rules for ELDU start to differ between nonfood producing- and food-producing animals. One critical difference concerns approved human drugs:

  • For nonfood-producing animals, a veterinarian may prescribe or dispense an approved human drug for ELDU even if an approved animal drug is available. However, use of a drug approved for animals is preferred.
  • For food-producing animals, extralabel use of an approved human drug is prohibited if there’s a drug approved for use in food-producing animals that could be used instead. 

Other differences, and further conditions, are explained below.

Further conditions for ELDU in food-producing animals

Certain drugs are prohibited from ELDU in food-producing animals. The FDA maintains a list of those drugs—many of which are antimicrobials—in 21 CFR 530.41. The information that follows pertains to non-prohibited drugs.

Before prescribing or dispensing an approved animal drug for extralabel use in food-producing animals, you must do all of the following:

In addition to the above conditions, both of the following conditions must be met for extralabel use when it comes to an approved human drug—or an animal drug approved only for use in nonfood-producing animals:

  • Ensure that such use is supported by an appropriate medical rationale, and that this rationale is recorded in the medical record.
  • If no scientific information is available on the human food safety aspect of the use of the drug in food-producing animals, you must take appropriate measures to assure that the animal and its food products will not enter the human food supply.
An important reminder

Extralabel use of an approved human drug in a food-producing animal is not permitted under 21 CFR 530.20 if there’s an animal drug approved for use in food-producing animals that can be used in an extralabel manner instead for the particular use. For example, if a drug approved for swine is available (but not a drug approved for cattle), you must first use that drug to treat a sick cow before choosing a drug approved for people.

Further conditions for ELDU in nonfood animals

Extralabel use of approved animal and human drugs in nonfood-producing animals does not ordinarily pose a threat to public health. Consequently, such use is generally permitted in nonfood-producing animals without restrictions, provided applicable conditions are met, except when public health may be threatened.

If the FDA determines that extralabel use of a certain drug in animals not intended for human consumption presents a risk to public health, the agency may publish in the Federal Register a notice prohibiting such use. The prohibited drug will be codified in 21 CFR 530.41, which is the same place FDA lists the drugs prohibited from extralabel use in food-producing animals.