Considerations for Treatment of Companion Food Animal or Pack Animal Species With Prohibited Substances
The previously detailed FDA-prohibited drug and drug class lists pertain to food-producing animals only and not to companion species such as dogs and cats. Veterinarians treat companion animals belonging to a food-producing species, but the FDA does not make a distinction between food-producing and companion status.
Even if the food-producing species with companion status are not to be slaughtered, consideration for why the prohibition exists should be carefully examined and prudent pharmacovigilance should be used. Practitioners who have used a prohibited substance in a companion or pack animal that subsequently enters the food supply are subject to enforcement actions under the Food, Drug, and Cosmetic Act. In choosing to use a prohibited drug in a companion or pack animal, the practitioner is accepting a certain amount of liability because the fate of such treated animals is often beyond their control. Practitioners may choose to have owners sign an agreement (entered into the medical record) not to introduce the animal into the human food chain.■ BOX 45.6
Requirements for Compounding in Veterinary Practice
1. No approved animal or human drug can be used in its available dosage form and concentration.
2. Only approved anιmalor human drugs are used in the compounding, specifically not foreign or bulk drugs.
3. Compounding is performed by a licensed pharmacist or veterinarian in compliance with state pharmacy laws.
4. Adequate procedures are in place to ensure the safety and effectiveness of the product.
5. Withdrawal intervals are set by the veterinarian, not by the pharmacist.
6. The scale of the compounding operation is commensurate with the established practice needs.
7. Allother AnimalMedicinalDrug Use Clarification Act requirements are met (see Box 45.3).
Compounding of Medications for Food Animals
Compounding is defined as a manipulation to produce a dosage form of a drug other than that provided for in the labeling, such as reconstitution.
The CVM recognizes the need for compounding within certain areas of veterinary practice, such as mixing or dilution. Because of the absence of safety, efficacy, and food safety data for compounded drugs, the potential exists for adverse reactions in treated animals or consumers of their products. In addition, if there are not sufficient scientific data to estimate a withdrawal for a compounded medication, it is the responsibility of the veterinarian to ensure that the animal and any food products that result from that animal do not enter the human food chain. Under AMDUCA, it is legal for veterinarians (or pharmacists on the order of a veterinarian) to compound from U.S.-approved animal and human drugs if the conditions listed in Box 45.6 are met.3Overall, when treating a food-producing animal, the use of compounded medications should be only a last resort because safety of the food chain should be the veterinarian’s priority.
Antidotes Compounded From Bulk Drug
Despite the prohibition, several chemicals commonly recommended as food animal antidotes are available only through compounding from bulk drug. As described in the previous section, compounding veterinary medications from bulk drugs is illegal. However, analogous to its policy concerning ELDU in feed for minor species, the CVM will not normally consider regulatory action against veterinarians compounding certain antidotes from bulk sources if certain conditions are met, essentially those listed in Boxes 45.3 and 45.6. The FDA is currently developing a new guidance document on compounding animal drugs from bulk drug substances (https://www.gpo.gov/ fdsys∕pkg∕FR-2015-05-19∕pdf∕2015-11982.pdf). Inquiries can be directed to the FDA-CVM, Division of Compliance, at 240-402-7002 or via email at AskCVM@fda.hhs.go. It is critical that veterinarians recognize that in toxicity cases, withdrawal periods will need to be established not only for the antidotes but also the toxicants. Some antidotes require substantially extended withdrawals, which may affect the decision to treat.13 As a practical matter, toxicity cases are frequently resolved based on testing in state or federal laboratories. Because of these complexities, practitioners are advised to consult the diagnostic laboratories and/or FARAD when dealing with such cases in food animals.