Compound Profile
Semax: An ACTH Fragment on the FDA's 2026 Review List
Published: August 24, 2026
TL;DR
Semax sits at an unusual intersection. Published literature describes a Russian-developed peptide with clinical use in that country. A ClinicalTrials.gov intervention search holds no registered Semax studies. In July 2026, FDA's compounding advisory committee reviewed its free-base and acetate forms and recommended both, 8 votes to 5 with one abstention. These records describe different systems, and none can stand in for the others.
Structurally, Semax joins a four-residue piece of ACTH to a synthetic three-residue tail without carrying native ACTH's hormonal activity. Curo's Semax research-material page appears in the research-peptide product catalogue. Lot documents can be found through the certificate of analysis database, and catalogue materials fall under the research use only policy.
An ACTH fragment without the hormone
Semax is a seven-residue peptide: Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues, Met-Glu-His-Phe, correspond to positions 4 through 7 of adrenocorticotropic hormone, or ACTH. A synthetic Pro-Gly-Pro tail follows them. This is why the compound is commonly described as an ACTH(4-10) analogue even though its construction is more precisely an ACTH(4-7) fragment plus that tail.
PubChem records CAS 80714-61-0, the sequence, and the synonym "ACTH (4-7), Pro-Gly-Pro-". The structural lineage does not give Semax the defining endocrine action of the parent hormone. It does not carry native ACTH's corticotropic activity.
The identity record is also visible in FDA's Global Substance Registration System under UNII I5FAL2585H. That entry gives the molecular formula C37H51N9O10S. Sequence, formula, CAS number, and UNII answer related but distinct identity questions. Together they make it possible to check whether a paper, registry entry, or analytical report refers to the same substance.
Where Semax came from
Semax was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences by the group of N.F. Myasoedov and I.P. Ashmarin. The same group developed the related heptapeptide Selank, represented separately in Curo's Selank research-material listing.
A peer-reviewed review from that research lineage describes Semax's development and its clinical use in Russia. What that establishes is a body of published work, which is a different thing from a current legal status, and the two do not track each other across borders.
Semax therefore enters the US research conversation with an established geographic context. Its source literature is heavily Russian and Russia-linked, while the familiar US registry view is nearly blank. The mismatch is informative about where research was conducted and documented. It is not, by itself, a conclusion about the quality or outcome of that research.
The 2026 compounding review
FDA's Federal Register notice set a Pharmacy Compounding Advisory Committee meeting for July 23 and 24, 2026, under docket FDA-2025-N-6895. The July 24 schedule covered "Semax (free base), Semax acetate" and considered cerebral ischemia, migraine, and trigeminal neuralgia.
Semax was one of seven substances on the two-day agenda. The others were BPC-157, KPV, TB-500, MOTS-c, emideltide, and epitalon. The BPC-157 research-record overview and the TB-500 and thymosin beta-4 distinction cover two of those neighboring entries.
The committee recommended both forms. Voting on the free base and the acetate separately, it backed each by 8 in favor to 5 against with one abstention. Hyman, Phelps & McNamara recorded the day-two votes and McDermott Will & Schulte published a matching tally table. FDA's staff had argued against listing: the agency's briefing document for Semax called the evidence insufficient for all three evaluated uses and raised possible bleeding, immunogenicity and characterization concerns, noting that much of the supporting literature is Russian-language and thin on route and dosing detail.
The recommendation is advisory and changes nothing by itself. A substance reaches the 503A list through FDA rulemaking, and Semax is not on that list. FDA's meeting page carries the briefing documents, the questions and the archived broadcast, but no minutes and no vote table, so the tallies rest on contemporaneous reporting.
An earlier document supplies context without deciding the 2026 question. A November 10, 2021 FDA warning letter to Advanced Nutriceuticals LLC, doing business as the Guyer Institute of Molecular Medicine, said that a group of substances including Semax "were not nominated for inclusion on the 503A bulks list." It was a general compliance letter to that firm, not an action focused on Semax alone.
What the trial registries hold
A ClinicalTrials.gov search for Semax as an intervention returns no registered studies. That result reflects where the work was done rather than whether it exists. The Russian and Russia-linked literature grew up inside a different research infrastructure, and it is not mirrored in the US registry.
The empty search result still matters. It means a researcher cannot use ClinicalTrials.gov to reconstruct a Semax development program through registered study identifiers, sponsors, endpoints, and posted results. Literature searches have to do more of the work, with close attention to source language, study design, and what each publication directly reports.
That contrast is the central feature of the record. Semax can have a history of reported clinical use in Russia, no registered intervention studies in the US database, and a place on a 2026 FDA compounding agenda at the same time. The facts coexist because they answer different questions.
Reading a Semax certificate of analysis
A certificate of analysis should connect a specific vial lot to a specific analytical report. Begin with the lot number, then compare the product name, reported material, test date, and methods. Curo's guide to matching a certificate of analysis to its lot explains that traceability step.
Curo's testing standard uses exactly three methods: HPLC, LC-MS, and endotoxin testing. HPLC reports chromatographic purity. LC-MS supports molecular identity by comparing mass data with the expected compound. Endotoxin testing addresses endotoxin burden. The quality and testing standard explains why the methods answer separate questions. A purity result alone is not an identity result, and neither replaces endotoxin data.
Storage belongs to the material-integrity record, but it does not substitute for analytical testing. The guide to research-peptide and bacteriostatic-water storage describes that separate documentation layer. For Semax, the chemical identifiers on a report should align with the identity record, while the lot number ties that report to the physical material.
Further reading
Selank came out of the same institute and shares the same Pro-Gly-Pro tail, but its parent sequence is tuftsin, a fragment of the immunoglobulin G heavy chain rather than a piece of a hormone. That lineage is traced in Selank, from an antibody fragment to anxiety research.
Epitalon, the last substance on that same two-day agenda, has a research record with a similar shape and a different centre of gravity. Its telomere findings sit entirely in cell culture, and its organism-level work is a rat carcinogenesis model and a study in aged rhesus monkeys. That record is mapped in Epithalon's record, from cell culture to rhesus monkeys.
Another compound from the same research tradition has a far thinner registry footprint than Semax does. Pinealon, the EDR tripeptide, has no registered trial and no FDA UNII, and its evidence sits in cell systems and two rodent models, as mapped in Pinealon: where the EDR tripeptide has been tested.
Common questions
Is Semax the same thing as ACTH?
No. Four residues come from the ACTH sequence, and a synthetic Pro-Gly-Pro tail completes Semax. PubChem's structural record describes that relationship, while also distinguishing Semax from native ACTH and its corticotropic activity.
What did FDA review in July 2026?
It reviewed Semax free base and Semax acetate for the 503A bulks list, against indications of cerebral ischemia, migraine and trigeminal neuralgia, and recommended both forms by 8 votes to 5 with one abstention. That is a non-binding recommendation to FDA, not an approval and not a listing.
Does an empty ClinicalTrials.gov search erase the Russian literature?
No. It shows that the US registry does not hold a registered Semax intervention study under that search. Published literature and trial registries overlap, but they are not identical archives, especially across jurisdictions and languages.
What should a Semax certificate establish?
It should identify the material, connect the report to a lot, and show results for the methods listed. HPLC, LC-MS, and endotoxin testing each supply a different part of that record. A certificate documents analytical findings for the lot; it does not establish a research outcome.