After much consideration—and considerable input from veterinarians—the US Food and Drug Administration (FDA) recently published Guidance for Industry #256: Compounding Animal Drugs from Bulk Drug Substances (GFI #256).

GFI #256 establishes the parameters within which veterinarians may use compounded drugs that are prepared from bulk drug substances, a topic that can be confusing, so NEWStat reached out to Marcy Bliss, Chief Executive Officer of Wedgewood Pharmacy, to find out what exactly veterinarians at AAHA-member practices need to know about the new guidance.

Like, what exactly is compounding?

“Traditional compounding means creating a customized medication, most often from raw ingredients, for an individual patient pursuant to a prescription,” Bliss told NEWStat, and pharmacists’ ability to compound medications from pure ingredients is authorized in federal law and for good reasons: “Manufactured drugs don’t come in strengths and dosage forms that are right for everyone, and physicians need to be able to prescribe customized medications when, in their medical judgment, a manufactured drug is not the best course of therapy for a patient.”

In short: animal drugs compounded from bulk drug substances (BDS) aren’t reviewed by the FDA, which means the agency hasn’t approved them as safe and effective for their intended use.

GFI #256 acknowledges that in the limited circumstances where there is no FDA-approved, conditionally approved, or indexed drug that can be used to treat an animal with a particular condition, an animal drug compounded from bulk drug substances may be a medically appropriate treatment.

It’s perhaps not surprising that many veterinarians aren’t more up to date on the ins and outs of compounding—Bliss estimates that less than 10% of animal health medications are compounded.

However, Bliss said compounding has its advantages, and veterinarians might want to consider prescribing a compounded medication under certain circumstances, which include:

• When the patient is allergic to certain preservatives, dyes, or binders in available off-the-shelf medications.
• When treatment requires tailored dosage strengths or delivery forms.
• When a pharmacist can combine several medications to increase adherence.
• When a patient cannot ingest the medication in its commercially available form.
• When medications require flavor additives to make them more palatable for patients.
• When there’s a shortage of required manufactured drugs. are in shortage, unavailable from pharmaceutical companies

GFI #256 has been in the works for a while.

“The FDA received more than 2,000 comments [from veterinarians, pharmacists, pharmaceutical companies, and other stakeholders] to their draft GFI, released in 2019, and we believe made important changes to ensure access to what the FDA acknowledges is a necessary tool in the veterinarian’s tool kit to treat patients,” Bliss said.  “This final GFI is written in plain language and provides examples that reveal some of FDA’s thinking more clearly.” 

Perhaps most importantly, GFI #256 identifies circumstances under which the FDA doesn’t intend to take regulatory action against the compounding of drugs from BDS when no other medically appropriate treatment options exist.

To sum up: “FDA’s GFI #256 introduces the current thinking of the agency about animal health medications compounded from bulk ingredients,” Bliss said. 

• The FDA believes most compounding should be done on a patient-specific basis, with veterinarian clinical rationale included with the prescription.
• If bulk ingredients are used in the compounding, the reason why should be documented. 
• If there are medications that veterinarians believe they need to order for office use, those medications may be nominated for consideration for office use. 

Bliss has a few reservations about the guidance: She said it’s missing specifics around the process to nominate ingredients for review and possible inclusion on a list of preparations that could be used for office use.  “Also concerning is that in human health, the bulk ingredient list is an ingredient list,” she added. “However, the construct of the FDA’s list includes a specific dosage form, strength, species, and does not allow the type of flexibility generally required to meet the variety of the needs of animal patients.” 

Fortunately, GFI #256 isn’t set in stone. Bliss told NEWStat that the FDA intends to meet with stakeholders to discuss the guidance in order answer questions and to clarify aspects of the guidance and its implementation.

“We hope to have the opportunity to meet with FDA about their views, to obtain clarification about aspects of the guidance that are unclear,” Bliss said, “and as always to advocate for veterinarians and our patients.”

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