By Ilisa Bernstein, Gail Bormel, and Kathy Anderson, Compounding Strategy Advisors, LLC

While working at FDA, we knew that warning letters were closely watched across the regulated ecosystem. Each one contains teachable moments about what FDA is seeing, what concerns the agency, and how FDA is applying the law and its policies to facts on the ground.

FDA’s September 18 warning letter to a state-licensed compounding pharmacy caught our attention. The letter addresses FDA’s concerns that certain compounded formulations of GLP-1 drugs are essentially copies of commercially available drug products made regularly or in inordinate amounts. In reaching this finding, FDA looked at several factors, including the claimed differences between the compounded and the FDA-approved drugs, how prescribers documented a significant difference for individual patients, the apparent use of standardized statements to support those determinations, and the volume and frequency with which certain drugs were being compounded.

There is a lot packed into FDA’s analysis. And the lessons go well beyond GLP-1s or the pharmacy that received the letter.

Teachable Moment #1: Look Beyond the Prescription

One thing jumped out at us immediately: FDA didn’t simply look at whether the prescription included the prescriber’s determination of significant difference. The agency instead questioned the repeated, apparently standardized statements about why a compounded drug was significantly different for a patient. In doing so, FDA considered whether the technology platforms may have allowed prescribers to select from pre-generated statements with pre-selected menu options.

That matters. Section 503A provides an important pathway for a prescriber to determine that a compounded drug produces a significant difference for an individual patient. But the words themselves aren’t magic words that provide a green light. According to FDA, the underlying question is whether the prescriber’s determination reflects an individualized clinical judgment for that patient.

As former regulators, the three of us recognize FDA’s consideration of the totality of the circumstances. When something on paper checks the regulatory box, but the surrounding facts raise questions (such as the repeated use of the same prescriber determination) regulators look further.

This is useful information for both compounders reviewing their own practices as well as the state boards of pharmacy overseeing pharmacy practice.

Teachable Moment #2: Volume Matters

FDA’s discussion of volume is a critical point in the letter that provides foundational insight into FDA’s analysis. FDA pointed to the volume of certain compounded drugs as one factor suggesting that purported differences between the compounded and the FDA-approved drugs are pretextual. It also relied on production records in concluding that certain compounded drugs were essentially copies made “regularly or in inordinate amounts.”

FDA did not establish a numerical threshold for “inordinate amounts.” FDA did not say that a large pharmacy or a pharmacy compounding a large number of patient-specific prescriptions is necessarily operating outside 503A. But volume can tell a story.

When compounding grows in scale, regulators and compounders themselves need to pay attention to whether the activity continues to reflect patient-specific compounding within the boundaries of the legal framework. This became painfully clear during the New England Compounding Center tragedy, when we saw the consequences of large-scale compounding and distribution that exceeded the bounds of pharmacy compounding. Much has changed in the compounding ecosystem since then. But one lesson remains important: when FDA points to volume, it is worth paying attention.

The question isn’t simply how many prescriptions are being compounded. It is what the volume tells us when considering everything else. What drug is being compounded? Why? For whom? How individualized is the prescribing? How standardized is the compounding?

Teachable Moment #3: Look at the Whole Picture

Another teachable moment in the letter is that FDA looks at the operation holistically:

• The type of drug product.
• A formulation difference.
• A prescriber notation.
• A technology platform.
• Production patterns.
• Prescription patterns.
• Significant-difference determinations.

Any one of these facts may have a perfectly reasonable explanation. Put them together, though, and they may tell a regulator something quite different about the nature of an operation.

This perspective is also important for state boards of pharmacy. We have repeatedly heard state regulators ask for more direction from FDA about where the agency sees the boundaries of 503A. Over the years, questions have included: What does “essentially a copy” look like in practice? What does a meaningful patient-specific difference look like? When does compounding become “regularly or in inordinate amounts”? And what should a regulator make of very large volumes of what is supposed to be patient-specific compounding?

This warning letter doesn’t answer all these questions. But it begins to put some facts around them.

And compounders should be reading it through the same lens. Not simply, “Does this apply to us?” but “What can we learn from the way FDA looked at these facts?”

Teachable Moment #4: FDA Communicating Its Thinking Matters

A warning letter isn’t a regulation, guidance document, or court decision. It reflects FDA’s conclusions about a particular set of facts, and the recipient has an opportunity to respond.

But that doesn’t diminish its value as a teaching tool.

All three of us have been on the regulatory side of these questions. We know how difficult it can be to translate statutory language into practical oversight—particularly when a marketplace is evolving much faster than the regulatory framework, given that 503A was passed in 1997, long before telehealth and digital commerce platforms.

FDA has put its thinking on a particular set of facts on the table. It is important to understand how FDA is thinking about these boundaries. And all of us benefit when difficult regulatory concepts are illustrated with real-world facts.

This letter doesn’t give us all the answers. But it gives us something important: teachable moments.

The post More than a Warning Letter: Teachable Moments for the Compounding Ecosystem first appeared on Compounding Strategy Advisors.