FDA allows compounded FIP drug in certain cases

On May 10, the Food and Drug Administration (FDA) issued a clarification regarding products compounded from the nucleoside analog GS-441524. GS-441524 is the active metabolite of remdesivir and has been used to treat feline infectious peritonitis (FIP).

The agency says it is aware of posts on social media suggesting that compounded GS-441524 will be “legally” available starting June 1 in the U.S.

“The FDA reminds compounding pharmacies, veterinarians and pet owners that animal drugs compounded from bulk drug substances are unapproved drugs and are not, in fact, legal,” the FDA announcement said.

A veterinarian treating, examining an ill cat at vet clinic
The Food and Drug Administration recently announced that it does not intend to enforce new animal drug approval requirements for the antiviral medication GS-441524, which must be prescribed by a veterinarian for a specific cat patient for the treatment of feline infectious peritonitis.

However, in its clarification, the FDA also indicated the agency will apply regulatory discretion to compounding GS-441524 so long as compounders follow Guidance for Industry (GFI) #256, Compounding Animal Drugs from Bulk Drug Substances.

GFI #256 describes specific conditions where the FDA doesn’t intend to take enforcement actions on products compounded for use in animals. It includes a requirement that products be compounded with patient-specific prescriptions and not for office stock, unless specifically authorized by the FDA. If veterinarians want to obtain animal drugs compounded from a bulk drug substance without a patient-specific prescription, the bulk drug substance should be nominated with a justification for its use, the agency says.

While remdesivir is FDA-approved and available for veterinary use under extralabel drug regulations that were promulgated under the Animal Medicinal Drug Use Clarification Act (AMDUCA), veterinarians have had trouble accessing this medication. This has furthered interest in compounding both remdesivir and GS-441524.

Recognizing that some feline patients may be sufficiently ill that medication would need to be available before a patient-specific prescription might be able to be filled, the AVMA and the American Association of Feline Practitioners are working collaboratively to submit nominations to the FDA to allow office stock for both remdesivir and GS-441524.

A version of this story appears in the July 2024 print issue of JAVMA