Semax
Also referenced as: ACTH (4-10) analogue, Met-Glu-His-Phe-Pro-Gly-Pro
A synthetic ACTH fragment analogue used clinically in Russia and unapproved elsewhere.
- Evidence grade
- EExperimental / Limited Evidence
Experimental / Limited Evidence
- Regulatory status
- Not FDA Approved
Registered as a medicine in Russia for certain neurological indications. Registration in one jurisdiction is not FDA approval and does not import that country's evidence standards.
- Human data
- Limited
No registered clinical trials identified
- Last reviewed
- September 1, 2026
Overview
Semax is a heptapeptide based on the ACTH (4-10) fragment, modified to remove hormonal activity while retaining reported neurotropic effects.
It is genuinely used in Russian clinical practice, mainly in stroke and cognitive indications. The supporting literature is largely regional and hard to appraise against international trial standards.
Why It's Being Studied
- Ischaemic stroke recovery and neuroprotection.
- Cognitive performance and attention.
- BDNF expression and neuroplasticity.
Mechanism of Action
It is a modified fragment of a stress hormone that appears to influence brain growth factors rather than hormone levels.
Semax lacks corticotropic activity but is reported to increase BDNF and its receptor TrkB expression in the hippocampus, modulate monoaminergic and cholinergic transmission, and affect the expression of neurotrophin and immune-related genes in rodent brain.
Research Areas & Routes Studied
- Stroke recovery
- Cognition
- Neuroplasticity
- Optic nerve disease
- Intranasal
- Intravenous (Russian clinical use)
Evidence Summary
Clinical use in Russia is supported mainly by Russian-language studies that are difficult to appraise and rarely independently replicated. Western clinical evidence is absent.
Human clinical evidence
- Russian studies in ischaemic stroke and cognitive disorders report benefit; methodology and reporting standards limit interpretation.
Animal studies
- Rodent studies on BDNF expression, learning and neuroprotection.
Anecdotal / community information
- Widely discussed in nootropic communities without controlled evidence.
Reported Adverse Events in Research
- Nasal irritation with intranasal use is reported.
- No systematic international safety data.
Limitations of Current Evidence
- Evidence base is regionally concentrated and rarely replicated independently.
- No established dosing protocol outside Russian product labelling.
Why It Is Used
- Cognitive
Focus, Mood and Cognitive Load
Two Russian-developed peptides used together for the same reason people pair a stimulant with an anxiolytic: attention without the edge.
Read the case study
Research References
- Animal study
Semax and BDNF expression in rat hippocampus
- Clinical trial
Semax in ischaemic stroke: published clinical reports