Semax

A peptide drug registered in Russia

Not FDA-approved · not available for sale or prescription

FDA advisory vote, July 2026 · FDA staff opposed · no FDA action

Stylised model of the real sequence

Overview.

Semax has no FDA or EMA approval, and much of its clinical literature is small and published in Russian. It is a synthetic heptapeptide fragment of ACTH developed in Russia in the 1980s. FDA's 2026 briefing describes it as a registered drug in Russia, sold as 0.1% and 1% nasal drops, and it is reportedly on the Russian government's List of Vital and Essential Drugs. Russian clinical studies have examined it in chronic ischemic brain disease, peptic ulcer, migraine and trigeminal neuralgia. US supply comes through research or compounded/gray-market channels.

Also known as Met-Glu-His-Phe-Pro-Gly-Pro · MEHFPGP

The molecule, decoded.

Sequence: MEHFPGP
Length: 7 residues
Molecular weight: 813.9 g/mol
Formula: C37H51N9O10S
CAS number: 80714-61-0
Half-life: Not established
Routes studied: intranasal (human, standard route for the Russian-approved product; also rat SCI model), intraperitoneal (animal ischemia models)
Modifications: none reported beyond the native peptide bond sequence (free N- and C-termini)

How it works.

Semax lacks the melanotropic/corticotropic activity of full ACTH; it is instead proposed to inhibit enkephalin-degrading enzymes, interact with melanocortin MC4/MC5 receptors, and elevate brain-derived neurotrophic factor (BDNF) expression in animal studies. RNA-sequencing studies in rat models of transient cerebral ischemia show it normalizes large numbers of ischemia-disrupted genes related to neurotransmission, inflammation, and neurogenesis/angiogenesis pathways. Its exact mechanism of action in humans has not been established.

Evidence · Approved outside the US (Russia) · limited evidence

What the research shows

narrative review2026

A 2026 narrative review of peptides in aging research grouped Semax with peptides whose main proposed mechanism is neuroprotection and classed it, like the other non-FDA-approved peptides discussed, as having preclinical or limited clinical evidence without long-term safety data or systematic validation.

narrative review across multiple peptides

Source

rat study2024

RNA sequencing of rat frontal cortex 24 h after transient middle cerebral artery occlusion found 3,774 ischemia-disrupted genes; Semax and the related ACTH(6-9)PGP peptide both significantly reduced the ischemia-induced changes for 1,171 of them (about 31%), mainly immune- and neurosignaling-related, consistent with a previously observed histological neuroprotective effect.

rat transient MCAO (ischemic stroke) model

Source

rat study2025

Intranasal ACTH(4-10)Pro8-Gly9-Pro10 (i.e., Semax) increased anti-inflammatory cytokines (IL-4, IL-10, IL-13) in the spinal cord of rats after acute spinal cord injury, more so in mild versus severe compression injury and at earlier (3 h) versus later (6 h) time points.

male Sprague-Dawley rat acute spinal cord injury model

Source

What to know first.

Based on: a Russian drug registration, small Russian clinical studies and animal research; human safety is not well characterized.

Reported side effects

Not systematically documented: clinical studies have been small and mostly published in Russian

Cautions

FDA's 2026 PCAC review found Semax not well characterized (immunogenicity and impurity concerns) and identified no acute or repeat-dose toxicity studies and no pharmacokinetic data for subcutaneous use; much of the clinical literature is small and published in Russian
US product is unregulated, gray-market, or compounded material rather than the Russian-approved pharmaceutical formulation

Checked 2026-09

Where it stands.

Not FDA-approved · not available for sale or prescription. Semax is not FDA-approved and is not available for sale or prescription. In July 2026, FDA staff recommended against adding it to the list of substances pharmacies may compound; FDA’s advisory committee voted 8–5, with 1 abstention, to recommend it anyway. The vote is advisory, and FDA has not acted on it.

FDA: Not FDA approved; investigational in the US. FDA's briefing describes Semax as a registered drug in Russia, sold as 0.1% and 1% nasal drops (citing Russia's State Register of Medicines), and it is reportedly on Russia's List of Vital & Essential Drugs. Reviewed at the PCAC on 24 Jul 2026 for cerebral ischemia, migraine and trigeminal neuralgia: FDA proposed NOT adding Semax (free base) or Semax acetate; the committee voted 8 yes, 5 no, 1 abstain on each form to recommend inclusion (non-binding). No proposed or final FDA rule as of 26 Sep 2026.
Approved products: Semax (Russian Ministry of Health): ischemic stroke/TIA, cognitive/memory disorders, peptic ulcer, optic nerve disease, immune support
Compounding: Nominated for the 503A Bulks List by LDT Health Solutions for the International Peptide Society (received 16 Nov 2018, FDA-2018-N-2973-0002) and by Wells Pharmacy Network (received 14 Dec 2020, FDA-2015-N-3534-0284). 'Semax (heptapeptide)' was held in 503A Category 2; both nominators withdrew on 14 Apr 2026 (FDA-2015-N-3534-0484/-0485), and it now appears under 'nominated but withdrawn' on FDA's Category 2 page (updated 22 Apr 2026). FDA presented Semax to the PCAC on 24 Jul 2026 and proposed NOT adding it; the committee voted 8-5-1 on each form to recommend inclusion (non-binding). As of 26 Sep 2026 FDA has published no proposed or final rule: the substance is not on the 503A bulks list (21 CFR 216.23, unchanged since 2019) and is not in 503A Category 1.
Sport (WADA): Not named in the WADA 2026 Prohibited List. Its Russian government drug approval likely places it outside the S0 'non-approved substance' criterion, which requires no approval by any governmental health authority.
Enforcement: FDA warning letter to Tailor Made Compounding LLC, dated 2020-04-01, names Semax among bulk substances compounded without qualifying for a Section 503A exemption.
Tailor Made Compounding LLC pleaded guilty in October 2020 to distributing unapproved new drugs, including Semax; on 24 Feb 2021 it was sentenced to three years' probation and forfeited $1,788,906.82, and its owner received probation, home incarceration and a $20,000 fine (U.S. Attorney's Office, E.D. Kentucky).
A 2020 forensic chemistry paper (Vanhee et al.) reported Semax (with Selank) in seized suspicious preparations in Belgium, prompting LC-MS/MS screening methods for control laboratories.

References (7)

Semax

Overview.

The molecule, decoded.

How it works.

What the research shows

What to know first.

Reported side effects

Cautions

Where it stands.

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