The 2026–2027 Compounding Question

What compounding pharmacies actually do

A compounding pharmacy is a licensed pharmacy that prepares custom medications from approved bulk substances. There are two kinds. A 503A pharmacy compounds patient-specific prescriptions one at a time, on the order of an individual physician for an individual patient. A 503B "outsourcing facility" compounds in batches under FDA-inspected current-Good-Manufacturing-Practice conditions and can ship to hospitals and clinics without patient-specific scripts.

Both rely on the FDA’s 503A Bulks List, which says which bulk substances can legally be used. If a substance is not on the list, neither type of pharmacy can use it. This is the lever the 2023 ruling pulled.

How a substance gets onto the 503A Bulks List

The list is curated by the FDA with input from the Pharmacy Compounding Advisory Committee (PCAC), an advisory body of pharmacists, physicians, and FDA staff that meets several times a year. Substances are nominated for inclusion, reviewed against six criteria (chemistry, safety, effectiveness, historical use, etc.), and then placed in one of four categories:

• Category 1 — Bulk substances under evaluation that may be used while the evaluation is in progress, with no significant safety risk identified.
• Category 2 — Substances identified as raising significant safety risks. May not be used in compounding.
• Category 3 — Substances that should be evaluated further; FDA has identified concerns or has not received sufficient information.
• Category 4 — Substances proposed for inclusion on the 503A Bulks List, which the agency intends to formally codify by rulemaking.

The 2023 ruling and the 19-peptide list

In 2023 the FDA moved 19 peptides into Category 2. The most prominent on the list are BPC-157, CJC-1295 (with and without DAC), Ipamorelin, Tesamorelin, Selank, Semax, Thymosin Beta-4, and Epitalon. The agency cited two reasons. The first was immunogenicity: synthetic peptides — especially modified ones — can trigger anti-drug antibodies, and there is no general way to predict that risk from sequence alone. The second was the absence of a USP monograph (a third-party-validated recipe and identity standard), without which the FDA cannot verify what is in the bulk vial.

Critics — including HHS Secretary Robert F. Kennedy Jr. — have framed the ruling as preemptive rather than evidence-based, arguing that "absence of efficacy data" should not by itself trigger a ban. The technical legal answer is that Category 2 does not require evidence of harm; it requires absence of evidence of safety. The structural disagreement is about which way that burden of proof should run.

What the 2026–2027 PCAC review will consider

The PCAC review of the Bulks List is expected to produce decisions on at least three fronts. First, whether any of the 19 peptides should move out of Category 2 — most likely on the basis of accumulated post-2023 clinical evidence or new USP monographs. Second, whether new peptides should be added to Category 2 or admitted to Category 1 / 4. And third, whether the procedural framework for evaluating peptides specifically should be updated.

The third item is potentially the most consequential. Peptides do not fit neatly into the existing small-molecule framework, because their immunogenicity and stability are sequence-specific in ways small molecules are not. A peptide-specific framework — analogous to the framework that biologics have under the BLA pathway — would make consistent regulation possible.

Three plausible outcomes

Outcomes range across a spectrum. Three feel most plausible in conversations with regulatory specialists today:

• Status-quo extension. The most heavily-discussed peptides remain in Category 2; the FDA continues to require human safety data the gray market is unlikely to generate. The compounding gray market continues to shift to less-regulated sourcing or moves offshore.
• Selective de-escalation. A subset of the 19 peptides — likely those with the most rigorous post-2023 immunogenicity data, such as Tesamorelin (which was already a previously-approved drug) — move to Category 3 or out of evaluation. BPC-157 and CJC-1295 most likely remain in Category 2.
• Framework refresh. A peptide-specific evaluation framework is published, separate from the existing small-molecule criteria. Re-evaluation of all 19 peptides happens against the new framework, with mixed outcomes per peptide.

Why this matters even if you don’t care about specific peptides

The 2026–2027 review is the most consequential regulatory event for the compounded peptide market in a decade. Beyond the specific peptides, it will set the precedent the agency uses for the next wave of peptides under development — including AI-designed peptides whose sequences won’t exist when the framework is decided. The framework defined for the 19 will be the framework that applies to the 19,000.

The right way to engage is not to advocate for specific peptides. It is to advocate for a defensible, peptide-specific evidence framework that the field can clear and the FDA can enforce. That is the conversation the next 12 months will determine.