Semax
A synthetic heptapeptide studied for its potential role in attention, working memory, and neuroprotection.
Semax has long attracted attention in neurobiological research. Its interest goes beyond the notion of cognition and touches several brain signalling mechanisms studied since the 1980s.
- Research Use Only
- Molecule under study
- Living document
- Current research state
- Used clinically in Russia since the 1990s; international research remains limited.
- Current clinical phase
- Approved in Russia (ischemic stroke, cognitive disorders) — not approved by the FDA/EMA
- Last update
- 20 juillet 2026 · Fiche v1.0
- Living document
- Updated regularly as research progresses.
What is Semax?
Semax is a small molecule called a "peptide". A peptide is a short sequence of amino acids — the basic building blocks of proteins.
It was developed in the late 1980s at the Institute of Molecular Genetics of the Russian Academy of Sciences, seeking to stabilize a natural fragment of a hormone called ACTH.
This fragment (positions 4 to 10 of ACTH) is known to influence memory and learning, but it is very rapidly degraded in the body. Adding a Pro-Gly-Pro motif to its end prolongs its duration of action.
Names you may come across
This molecule may appear under several names in the scientific, clinical or technical literature. Here are the main designations you may come across.
The official name used in scientific publications.
The chemical description: the stabilized 4-10 fragment of ACTH.
The single-letter code of the seven amino acids that make up the molecule.
Understanding it simply
A few simple reference points are enough to understand Semax.
A stabilized fragment
Semax reproduces a portion of a natural hormone (ACTH), but without its hormonal action. Only the effect on the central nervous system is retained.
A modulator, not a stimulant
Unlike caffeine or amphetamines, Semax does not act as an abrupt "jolt": it is studied as a subtle modulator of several neurochemical systems.
An unusual administration route
In studies, Semax is administered intranasally: the nasal mucosa provides direct and rapid access to the central nervous system.
La molécule ne donne pas d'ordre nouveau : elle ressemble à un messager que le corps connaît déjà et se fixe sur la même « serrure ». C'est pourquoi l'organisme la comprend naturellement.
The message "I've eaten enough" circulates more effectively: this is what explains researchers' interest in appetite.
What research shows today
Science advances step by step. We clearly distinguish what is firmly established from what remains under study.
- Structure and mechanism partially documented (analogue of ACTH 4-10 stabilized by Pro-Gly-Pro). — établi
- Modulation of BDNF and NGF expression observed in preclinical models. — établi
- Russian clinical trials published on ischemic stroke and cognitive disorders. — établi
- Few large international randomized controlled trials are available to date. — en cours
- Very long-term tolerability data are still being gathered. — en cours
Documented mechanism and clinical data published mainly in Russia; limited international experience and no approval by the FDA or EMA.
What the research shows
- Semax is described in the scientific literature as a stable analogue of the ACTH(4-10) fragment, without corticotropic hormonal activity.
- Preclinical studies report modulation of neurotrophic factor expression (BDNF, NGF) in the hippocampus.
- Russian clinical trials have evaluated its use in ischemic stroke and mild cognitive disorders.
What still remains to be studied
- International clinical data remain limited: few large-scale randomized controlled trials have been published outside Russia.
- The very long-term tolerability profile continues to be evaluated.
- No approval by the FDA or EMA to date; use outside the research setting is not regulated in most countries.
What we know today
Not all information carries the same weight of evidence. We therefore present it across three clearly distinct levels, from the most solid to the most indicative.
What scientific publications show
Scientific evidence- Russian publications report improvement in certain cognitive scores after ischemic stroke in treated patients.
- Preclinical work describes increased expression of BDNF (a neurotrophic factor) in the hippocampus of rodents.
- Modulation of the dopaminergic and serotonergic systems is documented in animal models.
What some professionals report
Documented- Publications stress the importance of supervised administration, in the context of specific indications (stroke, cognitive disorders).
- Trial authors note that Semax is not a stimulant and that its effects develop gradually.
What the community reports
Field observations- Users report a subjective improvement in concentration and mental clarity.
- Some report combined use with Selank to balance cognitive stimulation and calm.
Observations reported by the community do not constitute scientific evidence. Only controlled clinical trials are authoritative. In case of doubt, the advice of a qualified healthcare professional takes precedence.
How does Semax work?
Semax has no "single target": it acts as a modulator of several neurochemical systems at once.
Studied for its potential influence on the expression of neuronal growth factors (preclinical data).
Modulation observed in animal models — potentially related to attention and motivation.
Modulation described in several preclinical studies.
Semax inhibits the degradation of certain endogenous enkephalins (natural opioid peptides).
Each circle represents a natural signal being mimicked. The distinctive feature studied in Retatrutide is that it activates trois à la fois.
- 1Hippocampe · Cerveau
Region where increased BDNF is described in preclinical studies — involved in memory.
- 2Cortex préfrontal · Cerveau
Region associated with attention and working memory — often studied in cognitive assessments.
Each mimicked signal acts at a precise point in metabolism. It is their combined action that defines the studied profile of the molecule.
All of these mechanisms remain partially characterized in humans; most data come from animal models or small-scale studies.
Timeline des essais cliniques
A molecule under study progresses step by step. Here, simply, is where the research currently stands.
- Discovery· 1988Completed
Initial synthesis at the Institute of Molecular Genetics (Moscow)
Semax is designed as a stable analogue of the ACTH(4-10) fragment, with a Pro-Gly-Pro motif added to extend its duration of action.
- Preclinical· 1990sCompleted
Characterization of neurotrophic effects
Studies in animal models describe modulation of BDNF and NGF expression, as well as effects on the dopaminergic and serotonergic systems.
- Clinical· 1996-2000Completed
Registration in Russia
Semax is registered in Russia for certain cognitive and neurological indications, particularly in the context of ischemic stroke.
- Clinical· 2000-2020Completed
Russian trials in neurology
Several trials evaluate Semax in the context of acute ischemic stroke and post-stroke recovery (Skvortsova et al. studies).
- International· En coursOngoing
Evaluation outside Russia
Large randomized controlled trials outside Russia remain limited. Semax is not approved by the FDA or EMA.
Les analyses disponibles
The theory is put to the test. Here are the independent analyses already published for Semax, available in the Analyses Library.
The analyses for this molecule are currently being compiled.
Ouvrir la bibliothèque des analysesQuestions fréquentes
Is Semax a medication?
In Russia, yes, for certain cognitive and neurological indications. In the United States, Europe and most other countries, it is not approved for general use. PHL presents it for educational and reference purposes only (Research Use Only).
Why is it administered nasally in studies?
The intranasal route provides rapid access to the central nervous system via the nasal mucosa. This is the administration mode described in the majority of scientific publications.
Is Semax a stimulant?
No. Established: unlike caffeine or amphetamines, it does not act through direct, rapid stimulation. It is described in the literature as a discreet modulator of several neurochemical systems.
Are there clinical trials outside Russia?
To be studied: large-scale randomized controlled trials published outside Russia remain limited. This is one of the reasons why Semax is not yet approved by the FDA or the EMA.
What side effects have been reported?
Established: publications mainly report good short-term tolerability, with rare effects (nasal irritation, transient fatigue). To be studied: the full long-term profile, across large populations, is not yet consolidated.
Can it be combined with Selank?
Some Russian publications mention combined use (cognitive stimulation from Semax, anxiolytic action from Selank). However, this combination has not been the subject of large-scale international trials.
Publications scientifiques
Voici une sélection de publications de référence sur le Semax. Toutes sont réelles et vérifiables. La bibliographie continuera de s'enrichir.
Synthetic ACTH analogue Semax displays nootropic-like activity in humans
Kaplan A. Y. et al. · Neuroscience Research Communications · 1996
Nootropic analogue of adrenocorticotropin 4-10 – Semax (15 years experience in its design and study)
Ashmarin I. P. et al. · Zhurnal Vysshei Nervnoi Deiatelnosti Imeni I P Pavlova · 1997
Neuroprotective effects of Semax in acute period of hemispheric ischemic stroke (a placebo-controlled clinical trial)
Gusev E. I., Skvortsova V. I. et al. · Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova · 2005
Glossaire
- Peptide
- Une courte chaîne d'acides aminés, les briques élémentaires des protéines.
- ACTH
- Une hormone naturelle (adrenocorticotropic hormone) sécrétée par l'hypophyse ; le Semax en reprend un fragment sans son action hormonale.
- BDNF
- Brain-Derived Neurotrophic Factor : un facteur de croissance des neurones, étudié dans la mémoire et la plasticité cérébrale.
- NGF
- Nerve Growth Factor : un facteur de croissance des cellules nerveuses.
- AVC ischémique
- Un accident vasculaire cérébral causé par l'obstruction d'un vaisseau du cerveau.
- Intranasal
- Administration par le nez, via la muqueuse nasale.
- Nootrope
- Une molécule étudiée pour son influence sur les fonctions cognitives.
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Fiche de référence — version 1.0, mise à jour le 20 juillet 2026. The complete regulatory and scientific framework is gathered in the « Information importante » en tête de fiche.