The short version

Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.

What Semax is

Semax is a seven-residue peptide — Met-Glu-His-Phe-Pro-Gly-Pro — developed at the Russian Academy of Sciences and registered as a medicine in Russia. It is one of very few compounds in this library that is an approved drug somewhere. It is also one where the approved product and the product being sold have almost nothing in common.

The name is wrong, and a regulator has said so

Semax is described everywhere — including in paper titles by its own developers — as an "ACTH(4-10) analogue." Compare them:

Semax is ACTH(4-7) with Pro-Gly-Pro bolted on. The three residues that make ACTH what it is were the three that were removed. This is not pedantry: when FDA evaluated Semax in May 2026 it listed "inconsistent naming conventions" as the first of its reasons for concluding the substance is "not well-characterized from the physical and chemical characterization perspective." It also matters for the mechanism section, because those two missing residues are exactly the ones a melanocortin receptor requires.

How it is said to work

BDNF and NGF — measured, in rats, and messier than the marketing

The core finding is real. Dolotov and colleagues, 2006, found specific saturable binding sites in rat basal forebrain — K_d 2.4 nM — and increased BDNF protein. Earlier work reported increased BDNF expression across several rat brain regions.

Then a 2010 study looked at the time course across three tissues at once, and the answer was not a clean line going up. The authors' own phrase is "multidirectional activation of the expression": at twenty minutes, NGF and BDNF expression fell in hippocampus and retina while rising in frontal cortex. Retinal BDNF then rose at ninety minutes.

So the honest sentence is: Semax moves BDNF and NGF gene expression in rat brain, up in some regions and down in others, on a timescale of minutes to hours, at doses and by a route that do not correspond to how this product is sold. Nobody has measured BDNF in a human given Semax.

The melanocortin claim should be treated as refuted, not merely unsupported

You will see Semax described as acting through melanocortin receptors, on the strength of its being an ACTH fragment. The melanocortin pharmacophore is His-Phe-Arg-Trp. A 2022 review dedicated to melanocortin ligands states it plainly: four amino acids, His-Phe-Arg-Trp, are required for MC3R and MC5R activation; three, Phe-Arg-Trp, for MC4R; and the first seventeen residues of ACTH for MC2R.

Semax contains His-Phe and does not contain Arg-Trp at all — those are precisely the residues its designers replaced with Pro-Gly. At seven residues it cannot touch MC2R on length alone. That melanocortin review does not mention Semax anywhere. The Russian literature agrees from the other direction: Semax is described as an ACTH(4-10) analogue that is "completely devoid of any hormonal activity."

Other effects with real primary data, all in rats or mice: dopaminergic and serotoninergic activation, trkB regulation in hippocampus, immune and vascular gene expression after focal ischaemia, inhibition of enkephalin-degrading enzymes in human serum in vitro, and μ-opioid receptor regulation in mice after spinal cord injury.

Pharmacokinetics

No human pharmacokinetic study of Semax exists, by any route. That is not our search failing — it is FDA's finding, in writing, in 2026.

The 60–70% figure

Quoted everywhere as Semax's nasal bioavailability. Its actual source is the sentence in the Russian product information leaflet saying the drug is absorbed from the nasal mucosa and up to 60–70% is taken up. It carries no citation. It is a regulator-accepted claim in a product monograph, not a traceable measurement, and it should be quoted that way.

The "2 to 3 minute half-life" cites nothing

This number is on every vendor page. We followed it. The reference attached to it is a 2006 rat study of intranasal Semax distribution into brain and blood — a real paper, which reports no half-life at all: no C_max, no T_max, no bioavailability. What it reports is that two minutes after dosing, 0.093% of the administered radioactivity was present per gram of brain tissue, and 80% of that was still intact Semax.

The nearest thing to a measured half-life in the whole literature points the other way: a 2004 study found that against rat forebrain plasma membranes, "the half-life of Semax in the presence of the plasma membranes was demonstrated to be longer than 1 h." That is a test tube and rat tissue, not human plasma. Both the two-minute figure and the one-hour figure should be retired from any sentence about people.

What the evidence shows

There is a genuine clinical literature. It is Russian, it is largely Russian-language, none of it is registered, and none of it has been replicated outside Russia.

Registered trials on ClinicalTrials.gov: zero. No trial of the peptide Semax has ever been registered there.

The strongest thing that exists

Shmonin and colleagues, 2018, a meta-analysis of Semax in acute stroke. They screened 364 publications across PubMed and the Russian eLibrary; eight studies with 654 patients were suitable; three studies with 181 patients met inclusion criteria and shared endpoints. Intervention: Semax 1% intranasal, 12 to 18 mg a day in the first 10 to 14 days. They report improvement in neurological impairment, mobility and functional independence, concentrated in the severe and moderate strata.

Read that for what it is. It is the field's own meta-analysis, published in 2018, asking for the trial that would settle the question — which is a statement that as of 2018 the trial had not been done. One hundred and eighty-one patients, pooled from three heterogeneous Russian studies, with benefit appearing in some severity strata and not others.

A Western regulator's count of the entire human record

FDA reviewed Semax in May 2026 and tallied every human exposure it could find:

Doses ranged from a single 0.5 mg/kg to "2-4 drops per nostril three times a day for 10 days." FDA's assessment of the reporting quality, verbatim: "Most studies lacked detailed adverse event reporting." Only two studies were put forward as evidence of effectiveness, and FDA dismissed both — one for "small sample size, no blinding, no control group," the other because it was a meeting abstract. Its conclusion: "There is insufficient evidence of effectiveness to support use of semax (free base) or semax acetate for cerebral ischemia, migraine, or trigeminal neuralgia."

We could not read the individual Russian trials. Several are indexed on PubMed and one is catalogued by Cochrane as a controlled trial, but the abstracts sit behind access walls we could not get through, so we cannot tell you their sample sizes, randomisation or blinding. We are telling you that rather than describing studies we have not read.

Reconstitution

A 10 mg vial. The doses in circulation for injection are in the hundreds of micrograms, which makes dilution a precision question rather than a convenience one:

At 2 mL a 300 mcg dose is six marks on a U-100 syringe and a single-mark error is a 17% dose error. Going to the full 3 mL turns the same dose into nine marks, where the same single-mark error is 11%. The vial holds 3 mL, so that is the ceiling — there is no larger fill available, however much the precision argument might want one.

Reported protocols

This is the section that matters. The injectable dose in circulation does not correspond to anything — and it is far lower than the clinical evidence, not higher.

For scale: at the registered stroke dose of 12 mg a day, this 10 mg vial is less than one day. At the vendor convention it is a month. Those two facts describe the same compound.

One vendor page we found declines to give subcutaneous numbers at all, on the grounds that the strong data is intranasal and that dosing should not be moved between routes. That is a competitor being more careful than most, and we think they are right.

Storage

Lyophilised, sealed, cold, dark and dry. The handling conventions in our storage guide apply and are, as always, conventions carried across from peptides generally rather than published stability data for this compound.

One real datum does exist here, from the registered product rather than from us: the Russian nasal drops carry a two-year shelf life, and an opened bottle is 30 days at or below 25 °C. That is a solution in a preserved nasal formulation, not reconstituted lyophilisate, so it does not transfer directly — but it is the only manufacturer-set in-use limit that exists for this molecule anywhere, and it lands in the same region as the 28 days bacteriostatic water's preservative is validated for.

Reported effects

Semax has a decades-long clean record in Russia. It also has, by a Western regulator's account, no toxicology package at all. Both are true, and the second explains the first.

What the registered product's own leaflet says

The adverse reactions section of the Russian product information, in full, is that prolonged use may cause mild irritation of the nasal mucosa. On overdose it states that no overdose phenomena have been identified to date. Contraindications are hypersensitivity, age under 7, pregnancy and lactation, acute psychiatric states, anxiety disorders, and a history of seizures.

What FDA found when it went looking, in 2026

Four sentences from the same briefing document, quoted exactly:

There is one adverse event on the US FAERS system: a consumer reported ocular pain and burning after using Semax 0.1% nasal drops in May 2024, involving hospitalisation, with symptoms recorded as unresolved a year later. A single report proves very little in either direction. We are including it because it is the only one that exists.

Regulatory status

Russia — genuinely registered, and the form is nasal drops. Semax 0.1% nasal drops are registered to Peptogen, registration ЛП-№(009449)-(РГ-RU) dated 26 March 2025, indefinite duration, ATC N06BX. A separate 1% product is registered for a single indication, acute ischaemic stroke. Indications for the 0.1% product run from cognitive disorders in cerebrovascular disease through to adaptation and fatigue prophylaxis and minimal cerebral dysfunction in children aged 7 and over.

No injectable Semax product is registered in Russia, or anywhere else. The manufacturer's own product information describes intranasal administration only.

Two things we could not verify and are therefore not asserting: the widely repeated claim that Semax has been registered since 1994, which we could not find in any registry record or decree; and its current listing on Russia's Vital and Essential Drugs list, where the usual citation is a dead link.

Ukraine. Registered as nasal drops in both strengths. The certificate we can document, UA/1565/01/02, ran to 28 July 2014, and we could not confirm a current renewal. Note also that machine translations of the Ukrainian record render nasal instillations as "injections" — the dosage form on the same record reads unambiguously as nasal drops. Anyone citing a Ukrainian registration as evidence of an injectable product has hit that artefact.

Approved anywhere else. No. Not in the United States, the EU, the UK, Canada, Australia or Japan.

United States — reviewed once, in 2026, and the answer was no

Semax appears on FDA's published bulk drug substances page in the table of substances nominated but withdrawn, with the rationale that compounded drugs containing it "may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation and peptide-related impurities."

That page is no longer the whole story. FDA re-evaluated Semax and published a briefing document on 11 May 2026 — the first and only Western regulatory assessment of this compound that exists. Its conclusion, verbatim:

On 24 July 2026 FDA's Pharmacy Compounding Advisory Committee considered Semax alongside DSIP and Epitalon, under docket FDA-2025-N-6895, and legal commentators reporting from the meeting record it voting 8 to 5 with one abstention to recommend adding Semax anyway — against FDA's own stated position. A committee recommendation is advice. FDA is not bound by it, formal rulemaking has not happened, and nothing about the legal status of this compound has changed.

Worth noting what the nominations actually proposed, since it is the whole subject of this page: "intranasal spray or subcutaneous injection." FDA's answer on the injection half was that it could not find any literature on it.

Canada

Semax is not named in Health Canada's public advisory of 9 April 2026. That advisory names fourteen peptides — BPC-157, CJC-1295, DSIP, Epitalon, GHK-Cu, HCG, Ipamorelin, KPV, Melanotan I and II, MOTS-C, NAD+, SS-31, TB-500 and Retatrutide — and Semax is not among them.

Sport

Semax is not named on the 2026 WADA Prohibited List — we read the list and searched it. Here, unusually, the S0 catch-all may genuinely not apply either: S0 covers substances with "no current approval by any governmental regulatory health authority for human therapeutic use," and Semax holds a current Russian marketing authorisation. On a plain reading of the text, that takes it outside S0.

We are not telling an athlete this compound is permitted. That is a reading of list text, not a ruling, and we found no WADA determination either way. Section S2.2.2 prohibits corticotrophins and their releasing factors, and Semax is nominally an ACTH fragment analogue — the structural argument in the mechanism section says it is not corticotropic, but nobody has adjudicated that. Anyone subject to testing should ask their anti-doping organisation directly rather than relying on this paragraph.

Sentient Biogenix supplies Semax for laboratory research use only. It is not for human or veterinary use.

Questions we actually get

Isn't Semax an approved drug in Russia?

Yes — as nasal drops. That registration is real, current and verifiable. It is for a different dosage form, at doses between three and sixty times higher than what is sold for injection, and it says nothing about injecting the compound.

Has anyone studied injected Semax?

No. FDA looked for exactly this in 2026, because a compounder had nominated subcutaneous injection as a dosage form, and reported: "We were unable to find literature that discussed administration via subcutaneous injection ROA." Not one human study, by any injected route, for any endpoint.

Why is the injectable dose so much smaller than the registered dose?

Nobody knows. It is 40 to 400 times below the doses used in the clinical literature and below the bottom of the registered adult range. It was not derived from a bioavailability conversion, because no human bioavailability has ever been measured. It appears to be an assumption that injection is more efficient than a nose drop, with an invented divisor.

What's the half-life?

Unknown in humans. The "2 to 3 minutes" on every vendor page cites a rat study that reports no half-life at all. The only measured figure anywhere is over an hour, in a test tube against rat brain membranes. Neither number describes a person.

Is N-Acetyl Semax Amidate better?

It is a different molecule, and the argument for it is structural reasoning rather than data. There is no comparative pharmacokinetic study, no comparative efficacy study, in any species. Every piece of clinical and mechanistic evidence for Semax used plain Semax.

Is it on the Health Canada list?

No, and that is a genuine difference from most of this catalogue. It is also not permission. That list names products Health Canada seized, and the advisory says in terms that many other unauthorised peptides exist and should all be avoided.

References

1. US Food and Drug Administration. FDA Briefing Document, Pharmacy Compounding Advisory Committee — Semax-related bulk drug substances, 11 May 2026. fda.gov — the conclusion against listing, the absence of human pharmacokinetics, the absence of any injected-route literature, the human exposure tally, and the four toxicology findings quoted above.
2. US Food and Drug Administration. July 23–24, 2026 meeting of the Pharmacy Compounding Advisory Committee, docket FDA-2025-N-6895 — agenda and meeting materials. fda.gov
3. US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks — the nominated-but-withdrawn table. fda.gov
4. Peptogen. Semax 0.1% nasal drops — manufacturer's product information (Russian). peptogen.ru — registration number and date, dosage form, indications, dosing, the 60–70% nasal absorption statement, the adverse reactions and overdose sections, and the 30-day in-use limit. Cross-checked against the Vidal and RLS Russian drug registers.
5. Shmonin AA, Verbickaya EV, Soloveva LN, Malceva MN, Melnikova EV. Meta-analysis: Semax effectiveness in the acute period of stroke. Bulletin of Rehabilitation Medicine 2018;17(2):81–88. journals.eco-vector.com — 3 studies, 181 patients, 12–18 mg/day intranasal, and the authors' call for a proper double-blind trial.
6. Dolotov OV, Karpenko EA, Inozemtseva LS, et al. Semax, an analogue of adrenocorticotropin (4-10), binds specifically and increases levels of brain-derived neurotrophic factor protein in rat basal forebrain. Journal of Neurochemistry 2006;97 Suppl 1:82–86. PMID 16635254. pubmed.ncbi.nlm.nih.gov
7. Shadrina M, Kolomin T, Agapova T, et al. Comparison of the temporary dynamics of NGF and BDNF gene expression in rat hippocampus, frontal cortex, and retina under Semax action. Journal of Molecular Neuroscience 2010;41(1):30–35. PMID 19662538. pubmed.ncbi.nlm.nih.gov — the "multidirectional activation" finding.
8. Shevchenko KV, Nagaev IYu, Alfeeva LYu, et al. Kinetics of Semax penetration into the brain and blood of rats after its intranasal administration. Russian Journal of Bioorganic Chemistry 2006;32(1):64–70. PMID 16523722. pubmed.ncbi.nlm.nih.gov — the paper cited for a "2 to 3 minute half-life," which reports no half-life.
9. Dolotov OV, Zolotarev YA, Dorokhova EM, et al. The binding of Semax, ACTH(4-10) heptapeptide, to plasma membranes of the rat forebrain basal nuclei and its biodegradation. Russian Journal of Bioorganic Chemistry 2004;30(3):213–217. link.springer.com — the ">1 h" in-vitro half-life and the MEHFPGP → HFPGP → PGP degradation path.
10. Yuan X-C, Tao Y-X. Ligands for melanocortin receptors: beyond melanocyte-stimulating hormones and adrenocorticotropin. Biomolecules 2022;12(10):1407. pmc.ncbi.nlm.nih.gov — the His-Phe-Arg-Trp pharmacophore requirement. Semax is not mentioned in it.
11. Health Canada. Think twice before injecting peptides bought online: unauthorized products can seriously harm you. Public advisory, 9 April 2026. recalls-rappels.canada.ca
12. World Anti-Doping Agency. The 2026 Prohibited List, in force 1 January 2026, sections S0 and S2.2.2. Read via the Austrian Federal Law Gazette's official reproduction (BGBl. III Nr. 219/2025) because WADA blocks automated access to its own copy.

What we could not read, and have therefore not described: the individual Russian stroke and cerebrovascular trials indexed as PMIDs 11517472, 15792140, 29798983, 10199046 and 30225715; the 1996 human cognitive study by Kaplan and colleagues that is most often cited as proof of nootropic effect; and the single chemistry paper on N-acetylated Semax. Each exists and is indexed. None of their abstracts were retrievable, so this page reports their existence and nothing about their contents.