Semax

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Snapshot

Chemistry and make-up

Semax is a seven-residue linear peptide built from the ACTH(4-7) fragment (Met-Glu-His-Phe) with a Pro-Gly-Pro tail bolted onto the C-terminus [A]. That Pro-Gly-Pro addition is the whole point of the design: the terminal proline-rich cap blocks aminopeptidase and carboxypeptidase cleavage, so the peptide survives long enough in plasma and CNS tissue to be active, unlike native ACTH fragments which are degraded almost immediately [A]. It carries one methionine (the sulfur in the formula) and one histidine imidazole, but no cysteine, so there are no disulfide bridges and no metal-binding motif.

It is typically supplied as the acetate salt. As with any peptide sold “as the name only”, the CoA must state the salt form and the observed mass, because acetate content changes the effective peptide mass per milligram. A separate trap is the N-acetyl-Semax variant: vendors market it interchangeably with Semax, but N-terminal acetylation is a real covalent modification that changes mass and peptidase kinetics, so it is a different substance and must not be conflated with plain Semax on a CoA or a listing.

What it is studied for (evidence)

• Mechanism (preclinical [A]): up-regulates BDNF and NGF and their receptor signalling in the hippocampus and prefrontal cortex. A single application produced roughly a 1.4-fold rise in BDNF protein and a 1.6-fold rise in trkB phosphorylation in rat hippocampus (Dolotov et al., *Brain Res* 2006). Downstream it engages CREB, MAPK/ERK and PI3K/Akt survival pathways, modulates dopaminergic and serotonergic tone, and dampens pro-inflammatory cytokines and oxidative stress in ischaemia models [A].
• Established (within its evidence base): a consistent rodent and Russian clinical literature for neuroprotection in cerebral ischaemia and for attention/cognition. Semax is a registered medicine in the Russian Federation, listed in the state register of medicines (GRLS, grls.rosminzdrav.ru) as a nootropic for cerebrovascular and cognitive indications; within Russia this counts as approved clinical use [B — GRLS state register is the primary source]. The commonly repeated “since 1994” origin date comes from secondary reviews and could not be confirmed against a specific GRLS registration certificate in this pass, so treat the exact year as unverified [D].
• Emerging / thin: almost all higher-quality human data is Russian-language, single-region, and small by Western standards. There is no large randomised placebo-controlled Western trial and no FDA/EMA/MHRA approval for any indication. Independent Western replication of the BDNF-driven cognitive claims is limited [A]. Treat the mechanism as well-described in animals but the human efficacy as regionally-established at best, unproven by Western regulatory standards.
• Marketing claims vs data: vendor and clinic pages present Semax as a proven human nootropic (“boosts focus, memory, mood”) and publish intranasal dosing protocols. The human evidence does not support treating those as established outside the Russian clinical setting, and responsible vendors publish none of the dosing. Claims that it “treats” ADHD, depression, stroke or brain injury pull the product into medicine-by-presentation territory and must be avoided.
• Human clinical status: approved and prescribed in Russia and some CIS states; not approved in UK, EU or US. No Western marketing authorisation.

Handling, format and stability

Supplied lyophilised. Research handling reconstitutes with bacteriostatic water (no dosing guidance here). Lyophilised powder is the stable form: vendor and stability guidance puts it at roughly 24 months or more at minus 20 C desiccated and dark, around 12 months at 2 to 8 C, and only weeks at room temperature once in solution [D — vendor stability claims, verify against your own CoA/stability data]. Reconstituted solution is cold-chain dependent and light-sensitive. Note the format split in the market: Semax circulates both as research lyophilised vials and as intranasal sprays (often Semax plus Selank combinations); the spray format is a human-use presentation and is not how a reputable supplier should list a research product.

Regulatory and trade status

• UK/EU RUO: legal to sell and possess as a research chemical; not a licensed medicine in the UK or EU. Any human-use or treatment claim triggers the Human Medicines Regulations 2012 and MHRA scrutiny, so listings and emails must stay strictly research use only [B].
• Russia/CIS: registered prescription medicine (the origin of essentially all clinical data), listed in the Russian state register of medicines (GRLS) [B]; the “since 1994” date is secondary-sourced and not independently confirmed here [D].
• US: not FDA-approved and not submitted; sold only as a research chemical labelled not for human use. In April 2026 Semax (acetate and free base) was removed from 503A Category 2 and referred to the Pharmacy Compounding Advisory Committee, and on 24 July 2026 the PCAC voted 8 to 5 (1 abstention) to recommend Semax for the 503A bulks list [B] (FDA PCAC July 2026). This is an advisory recommendation only, not a rule; it still requires FDA rulemaking (realistically into 2027) and does not change the UK sell-as-RUO position. Worth tracking for direction of travel.
• WADA (sport): not an approved human drug in the WADA-relevant jurisdictions, so it is treated under S0 (non-approved substances) and should be regarded as prohibited in sport. WADA does not list Semax by name [B — verify current wording].
• Customs: lower profile than the GLP-1 class; the main trade risks are marketing language and the Semax vs N-acetyl-Semax identity question.

Sources

• [A] Dolotov et al., “Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus”, *Brain Res* 2006 — https://www.sciencedirect.com/science/article/abs/pii/S0006899306022955
• [B] Russian state register of medicines (GRLS), primary registry for the Semax registration — https://grls.rosminzdrav.ru
• [B] FDA, Bulk Drug Substances Used in Compounding under 503A (Semax removed from Category 2 April 2026; PCAC recommended it 8-5 on 24 July 2026) — https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
• [B] WADA Prohibited List (S0 non-approved substances) — https://www.wada-ama.org/en/prohibited-list
• [B] PubChem CID 9811102 (C37H51N9O10S, MW 813.9)
• [D] Vendor/clinic pages (Peptidepedia, Swolverine, nasal-spray retailers) — commercial; publish dosing and human-use claims we do not use; treated as leads only.

Plain summary

Semax is a Russian-developed seven-amino-acid brain peptide that raises BDNF and NGF in animal studies and is a registered stroke and cognition medicine in Russia (listed in the GRLS state register; the often-quoted 1994 start date is secondary-sourced), but it has no UK, EU or US approval and almost no large Western trial evidence, so its human benefits are regionally-claimed rather than independently proven. Commercially the biggest traps are naming and identity: plain Semax and the acetylated N-acetyl-Semax are different molecules, and it is often sold as a human-use nasal spray, so responsible vendors keep listings research use only and demand a CoA that states the salt form and the observed 813.9 mass.

For laboratory and research use only (RUO). Not for human or veterinary use, not for consumption, and not a medicine. Information is a research summary, not medical advice, and contains no dosing guidance.

For laboratory research use only. Not for human or veterinary use, not for consumption, and not a medicine. This is a research summary, not medical advice, and contains no dosing guidance.