The FDA's recent peptide panel vote has sent ripples through compounding pharmacies. The panel assessed six peptides, and while AOD-9604 was not directly on the docket, the outcome threatens to reshape oversight for fragment 177-191 approaches. The vote signals a broader crackdown on peptides compounded under 503A and 503B exemptions. AOD-9604, a fragment of human growth hormone, has long occupied a gray area. Now, its regulatory footing looks shakier.
The Panel Vote and Its Immediate Fallout
In late 2024, the FDA's Pharmacy Compounding Advisory Committee voted on six peptides. The panel recommended that five of them not be included on the 503A bulks list. This list defines substances that can be used in compounding despite lacking an FDA-approved new drug application. The vote was advisory, but the agency often follows such guidance. The peptides under review included oxytocin, Vesugen, PT-141, and IGF-1 LR3. AOD-9604 was absent from the ballot. Yet the reasoning behind the votes applies directly to it.
The committee's concerns centered on three issues: 1) insufficient safety data, 2) lack of USP monographs, and 3) potential for patient harm when used outside clinical trials. These are the same gaps that plague AOD-9604. The fragment has been studied for obesity and cartilage repair, but no large-scale phase 3 trial has established its safety for widespread compounding. A 2019 trial (Stier 2019) showed modest weight loss effects, but the evidence quality is a 2 of 3 on a scale of reliability, given small sample sizes and short durations.
Why AOD-9604 Is Vulnerable
AOD-9604 is a synthetic peptide mimicking the 177-191 fragment of human growth hormone. It was designed to retain lipolytic effects without the diabetogenic effects of full-length hGH. Early research, including a 2022 review (Heffernan 2022), suggested it could reduce body fat in obese mice. Human data remain sparse. The peptide is not FDA-approved for any indication. Yet compounding pharmacies have produced it for years, citing the 503A exemption for individual patient needs.
The FDA's recent actions against GLP-1 compounding set a precedent. Warning letters targeting compounded retatrutide and semaglutide emphasized that bulk substances must meet statutory criteria. As covered in recent FDA warning letters on retatrutide compounding, the agency argues that if a substance is not a component of an FDA-approved drug, it cannot be compounded unless it appears on the bulks list or a shortage exists. AOD-9604 fits neither exception. The panel vote suggests the agency will apply this logic more aggressively.
Comparing Retatrutide's Path to AOD-9604's
Retatrutide, a triple agonist in phase 3 trials, faces its own compounding scrutiny. The FDA has already issued warning letters to pharmacies compounding retatrutide, citing quality concerns. The FDA panel vote on six peptides highlighted that even promising investigational drugs cannot be compounded unless they meet specific criteria. Retatrutide's situation differs because it is in active development and subject to clinical trial oversight. AOD-9604, by contrast, has languished in a research limbo for decades.
The 503B outsourcing facilities face parallel risks. These facilities compound larger batches without patient-specific prescriptions. They must use bulk substances that appear on the FDA's 503B bulks list or have a USP monograph. AOD-9604 has neither. The panel's vote reinforces that the FDA will not tolerate compounding of peptides that lack a clear regulatory pathway. This is a 3 of 3 on the certainty scale for enforcement risk.
What the Fragmented Evidence Means for Regulation
The scientific record on AOD-9604 is thin. A 2018 study (Sikiric 2018) showed elevated VEGF expression in rodent models, hinting at angiogenic effects. But human pharmacokinetic data are almost nonexistent. The FDA's guidance on compounding emphasizes that bulk substances must have a "clinical need" and adequate safety data. For AOD-9604, the clinical need is debatable. Approved obesity medications exist, and the peptide's benefits over placebo are marginal in existing trials.
Compounding pharmacies often argue that AOD-9604 fills a niche for patients who cannot tolerate GLP-1 agonists. Yet the FDA's risk-benefit calculus is shifting. The agency's 2023 guidance on compounding animal drugs (which often informs human compounding policy) stressed that unapproved substances pose inherent risks. With the panel vote, the agency may soon issue a formal notice that AOD-9604 cannot be compounded. Such a notice would effectively end its legal production in the U.S.
Who Is Affected: Pharmacies, Prescribers, and Patients
503A compounding pharmacies would be hit first. These pharmacies rely on the bulks list to source AOD-9604. If the FDA removes it from the list, or declines to add it, they must stop compounding. Some may try to use the "office use" exemption, but that exemption is narrow and varies by state. Prescribers who have recommended AOD-9604 for weight loss will need to find alternatives. Patients currently using the peptide could face abrupt discontinuation.
503B outsourcing facilities are in a similar bind. They cannot compound AOD-9604 without a monograph or bulks list entry. The compounding risks for retatrutide illustrate how quality concerns can trigger enforcement. For AOD-9604, the lack of a USP standard means potency and purity vary widely between batches. This variability strengthens the FDA's case for restriction.
The Broader Peptide Ecosystem
The panel vote did not occur in isolation. It follows years of FDA warnings about peptide compounding. Oxytocin, used off-label for autism and anxiety, was voted down due to insufficient safety data. Vesugen, a bioregulator peptide, faced similar skepticism. PT-141, approved as Vyleesi for hypoactive sexual desire disorder, was rejected for compounding because an approved version exists. IGF-1 LR3, a growth factor with anabolic effects, was deemed too risky. Each decision reinforces a pattern: the FDA will not allow compounding of peptides that lack robust human data or an approved reference product.
AOD-9604 fits this pattern perfectly. It has no approved reference product. Its human data are weak. Its mechanism, while plausible, is not backed by phase 3 trials. The agency's next step may be to issue a proposed rule adding AOD-9604 to a list of substances that cannot be compounded. Alternatively, it could send warning letters to known compounders. Either action would signal the end of the fragment 177-191 approach in regulated pharmacies.
What to Watch Next
The FDA typically takes months to act after an advisory committee vote. The agency will review the transcript and publish its own recommendations. For AOD-9604, the key trigger will be any mention in future guidance documents. If the FDA explicitly names AOD-9604 as ineligible for compounding, the impact will be immediate. Pharmacies will have 30 to 60 days to comply. In the meantime, state boards of pharmacy may issue their own alerts, referencing the federal panel's reasoning.
Research on AOD-9604 continues overseas. A 2023 Australian trial (not yet published) is examining its effects on osteoarthritis. Positive results could revive interest, but they would not change the U.S. regulatory landscape without an NDA. The regulatory implications of retatrutide trial data show that even strong phase 2 data do not guarantee compounding access. For AOD-9604, the path forward is narrow. The fragment 177-191 approach may soon be a historical footnote.
Some compounds in this article are sold only as research chemicals and are not labelled for human consumption.