FDA Issues Draft Guidance on Compounding Animal Drugs from Bulk Drug Substances Under Current Good Manufacturing Practice in Federally-Registered Facilities
August 27, 2026
The U.S. Food and Drug Administration is requesting public comment on a draft guidance for industry (GFI) #256B, entitled “Compounding Animal Drugs from Bulk Drug Substances: Compounding under CGMP in Federally-Registered Facilities.” This draft guidance details when the FDA generally would not intend to take enforcement action against the compounding of animal drug products from bulk drug substances (BDS) when done in accordance with Current Good Manufacturing Practice (CGMP) at FDA-registered drug production facilities. The FDA exercises enforcement discretion regarding animal drug compounding from BDS under certain circumstances when no other medically appropriate treatment options exist. This guidance proposes to clarify the scope of the existing enforcement discretion policy as described in final GFI #256, “Compounding Animal Drugs from Bulk Drug Substances.” Once finalized, the new guidance will be combined with GFI #256.
Under the Federal Food, Drug, and Cosmetic Act (FD&C Act), the compounding of an animal drug from BDS results in a new animal drug that must comply with the FD&C Act’s animal drug approval, conditional approval, or indexing requirements. In addition, all animal drugs are required to be made in accordance with CGMP and have adequate directions for use. Although animal drugs compounded from BDS do not comply with these FD&C Act provisions, this draft guidance proposes enforcement discretion that balances the needs of animals, veterinarians, and animal owners with FDA’s responsibility to keep the human and animal food supply safe and to ensure that animal drugs are safety and effective.
FDA limited the enforcement discretion policy in GFI #256, published in August 2022, to drugs compounded by veterinarians or pharmacists in State-licensed pharmacies or federal government facilities. Since publication, FDA received questions regarding the applicability of GFI #256 to animal drug compounding in other types of facilities. In response, draft GFI #256B extends a similar enforcement discretion policy to outsourcing facilities registered under section 503B of the Act, as well as federally-registered drug manufacturers. We are proposing this change because outsourcing facilities that compound animal drugs in addition to human drugs do not qualify for the enforcement discretion under GFI #256 if they are not licensed as pharmacies. We propose extending the enforcement discretion policy to federally-registered facilities to provide additional flexibility for veterinarians and animal owners when FDA-approved treatments are not an option. The enforcement policy in GFI #256B would not exempt outsourcing facilities or manufactures from CGMP requirements. This draft guidance does not cover animal drugs compounded for use in investigations of new animal drugs, animal drugs compounded by a pharmacy that is not federally-registered, or animal drugs compounded from FDA-approved animal or human drugs.
This draft guidance also responds to congressional interest. The Senate Report (No. 119-37, page 130) for the FY26 Agriculture Appropriations encouraged FDA “to provide public clarification on the role of Animal Drug Compounding in outsourcing facilities registered under section 503B of the Federal Food, Drug, and Cosmetic Act.”
The FDA is accepting public comments on draft GFI #256B beginning on August 28, 2026. The guidance’s notice of availability also contains specific topics and questions that FDA requests commenters consider addressing. To electronically submit comments to the docket, visit www.regulations.gov and type FDA-2018-D-4533 in the search box.
Comments on draft GFI #256B will be accepted at any time, but should be submitted no later than November 27, 2026, to ensure that the FDA takes the information into consideration before making further decisions on this issue. To submit comments to the docket by mail, use the following address. Be sure to include docket number FDA-2018-D-4533 on each page of your written comments.
Dockets Management Staff
Food and Drug Administration
5630 Fishers Lane, Room 1061
Rockville, MD 20852