The PEPTIDE-L Wave Rolls On! PCAC Adds Two More Bulk Drug Substances for the 503A List
Well, don’t say we didn’t tell you what was coming.
Day 2 of the Pharmacy Compounding Advisory Committee (PCAC or the Panel) Meeting (mostly) followed in the footsteps and at the pace of Day 1 (see our prior coverage of Day 1). Over the course of the day, the Panel worked through three more nominated peptides for possible inclusion on the Section 503A bulk drug substances list, ultimately recommending two—Epitalon and Semax—for inclusion, while declining to recommend Emideltide (the delta sleep-inducing peptide, aka “DSIP”). Was the DSIP “no-vote” the sacrificial lamb here? As on Day 1, the real drama was less in the vote counts than in the recurring, and still-unresolved, question that FDA pressed from the outset: When a prescriber writes a prescription for one of these peptides, does anyone actually know what the patient is receiving?
FDA: “A Volvo with NASCAR Specs”
FDA opened by reprising its Day 1 themes and answering questions the Panel had raised the day before. The Agency reminded the Panel that none of these substances is an FDA-approved drug, that any clinical investigation would require an IND, and that 503A compounders are not required to submit adverse event reports, so the Agency simply does not receive that information. FDA asked the Panel to weigh the absence of information as its own data point.
FDA’s Russ Wesdyk leaned into an analogy, likening the exercise to picking a car that is safe for your teenager: The manufacturer makes the nomination, but you may end up with “a Volvo with NASCAR racecar specs,” the same nameplate over a different amino acid count and molecular weight. The name is fixed; the numbers under it are not. Turning to “characterization,” FDA noted that “TB500,” a substance discussed on Day 1, typically refers to a 17-amino-acid fragment, but exact sequences and molecular weights vary between vendors, prompting the pointed question, “When you write a script for TB500, what form do you think your patients are receiving? Does anyone know?” The Agency stressed that it lacks the authority to define what TB500 is, drawing a comparison to the possibility that the most widely used form of a peptide might not even be the form its inventor discovered or patented (if even a patent were to exist).
“Process” v. “Substances” v. “Application” – What are we doing here?
Panel members quickly zeroed in on the “mechanics” of a peptide. Panel member Kevin Zacharoff, a Clinical Assistant Professor and Course Director of Pain and Addiction at the Renaissance School of Medicine at Stony Brook University, asked whether the Panel was being asked to evaluate the process for making a peptide or specific compounds within it, noting uncertainty over whether a vote concerned one substance or many forms of a substance sharing a common name. FDA acknowledged the difficulty: because these are “common name” substances with many possible forms, the open question from Dr. Zacharoff persists, “What form exactly do you want me to put on the list?” When asked who regulates that question, Russ Wesdyk’scandid answer for the Agency was that one “would need to ask a lawyer.” Well, being lawyers here, the answer is somewhat unclear; but we can take a good guess.
Panel members also underscored the limits of the record before them. FDA explained that there is no drug “application” here; there’s only a public nomination, reviewed based on whatever information is submitted (often less than ideal), supplemented by what the Agency can find in the public domain. As Panel member and patient representative Joshua Mailman, observed, because there is no common dosing schedule, route of administration, or tracking of drug interactions, none of the data generated in the 503A context could support a conventional FDA drug approval process. FDA’s Office of New Drugs agreed that such information might be supportive of an IND or NDA but could not supplant the clinical evidence of safety and efficacy that approval requires.
Emideltide (DSIP): Not Today
The Panel’s discussion of Emideltide drew sharp opposition—but we note so did the Panel’s discussion of many of the nominated peptides. Public Citizen’s Mary Ezren strongly supported FDA’s assessment against inclusion, flagging that the common name covers different active molecules, that there are immunogenicity concerns tied to incomplete impurity data, and that the efficacy data are flawed (i.e., small trials, with nothing more recent than 1992). Dr. John Hertig, Chairman of the Board for the Collaborative for Evidence-Based Medicines, echoed that the sole supporting study is over 30 years old, and warned that once a substance is on the list, the Panel “loses control” over what is ultimately for them a binary choice.
Proponents offered a mix of history and anecdote—one speaker recounted the peptide’s 1977 discovery in the cerebral venous blood of rabbits and its role in regulating sleep architecture without inducing sleep, and others emphasized longevity and circadian applications. Former Puerto Rico Governor Ricardo Rosselló cautioned that “waiting for perfect certainty” is itself a consequential policy choice. Rosselló made this point for each substance discussed on Day 2.
The vote on Emideltide (free base and acetate) failed, 6 in favor to 7 against, with 1 abstention. Dissenting members cited low-quality efficacy evidence, poor characterization, the existence of approved therapies, and the complexity/uncertainty of the dosing regimen.
Epitalon: A Relatively Narrower “Yes”
Epitalon fared better. Opponents pressed on carcinogenicity—noting a proposed mechanism theoretically linked to cancer via telomere signaling, a concern amplified by chronic dosing—and on the regulatory patchwork that would result from leaving the substance to the states. There was also a pointed exchange over whether Epitalon is registered in Russia as a dietary supplement, which FDA said it would look into.
The vote on Epitalon passed, 7 in favor to 4 against, with 1 abstention. Several members in the majority stressed that they were applying 503A criteria—not Phase I or general NDA standards—and would defer to the physician and pharmacist to guide individualized care.
Semax: The (Relatively) Clearest Track Record
Semax drew perhaps the most developed proponent case, anchored by its purported three decades of international use, its mechanistic story (upregulation of neural growth factor BDNF and its receptor TrkB), and study data around neuroprotection and cerebral ischemia. FDA countered that the available literature—much of it in Russian—often lacked the routes of administration, dosing, and study details needed to verify the study’s claims/outcomes. In addition, Brian Serumaga, Acting PCAC Chairperson and USP representative, flagged a health literacy risk: the common name could easily be confused with Semaxanib, a distinct compound.
The vote on Semax passed, 8 in favor to 5 against, with 1 abstention. Members in the majority framed their votes as recognizing a decision “patients are already making” and bringing it into a regulated framework of licensed pharmacies and testing. Dissenters pointed to weak preclinical evidence, characterization concerns, and the risk of steering patients away from evidence-based therapies for serious conditions.
FDA: Creating—NOT Restoring—Access
Threaded through the day was a recurring correction from FDA. As FDA’s Matthew Lash, Acting Director of the Office of Compounding Quality and Compliance, explained, Section 503A, enacted in 1997, permits compounding of a bulk substance only through one of three pathways—when a substance is a component of an approved drug, subject to a USP monograph, or included on the bulks list—and these peptides fall outside the first two. FDA pushed back on the framing that adding them would “restore” post-2023 access, characterizing it instead as the “first time creating legal access,” with uncertain consequences for the scale of availability. The Agency also emphasized that the withdrawal of the underlying nominations (specifically, all industry nominations had been withdrawn in the months prior to the PCAC meeting) was not a factor in its evaluation, and urged members not to weigh it in their votes.
Takeaways for Industry
Day 2 concluded leaving compounders, prescribers, and manufacturers with a predictable set of open questions. Two more peptides advanced toward the 503A bulks list Category 1, bringing the total from this PCAC meeting to six; but the votes were relatively close and the Panel’s own members repeatedly acknowledged the tension between individualized patient access and the significant evidentiary and characterization gaps FDA identified. With FDA confirming that this is a notice-and-comment rulemaking in which it will analyze the full record—including materials submitted after its June 2026 evaluations—the proposed rule, not the Panel’s recommendations, will be where these debates are ultimately resolved. And with FDA signaling that additional peptides are already queued for a future PCAC meeting, this is just the beginning.
But What’s Next Here?
The compounding and peptide industry is chomping at the bit concerning who can make it across the finish line fastest. We need FDA to determine—quickly—any needed next steps. If not, the “gray/black market” production and distribution will continue. And one of the reasons the PCAC meeting occurred—as addressed through multiple comments over two days—is to rein in the gray/black market and create some guardrails for use. One option would be placing these “approved” peptides on FDA’s interim Category 1 list (along with all other API awaiting rulemaking) and, as a condition to FDA’s grant of enforcement discretion, put some clear procedures in place at least on a temporary basis. Some thoughts include (for these peptides only) but are not limited to requiring adverse event reporting, and appropriate, sourcing, grading, identification, and release testing of the bulk substances.