Semax
A Russian-developed synthetic heptapeptide registered for stroke and neurological disorders in Russia — with genuine human clinical data, but almost entirely from Russian research groups and with no independent Western replication
🧑🐀 Both
- Full name
- Semax (Met-Glu-His-Phe-Pro-Gly-Pro)
- Class
- Synthetic heptapeptide; ACTH(4–7) analogue with C-terminal Pro-Gly-Pro stabiliser
- Molecular weight
- ~813.0 g/mol
- CAS number
- 80714-61-0
- Sequence
- Met-Glu-His-Phe-Pro-Gly-Pro
- First synthesized
- 1980s–1990s, Institute of Molecular Genetics, Russian Academy of Sciences (N.F. Myasoedov group)
- Regulatory status
- Registered prescription drug in Russia for ischemic stroke, transient ischemic attack, optic nerve disorders, and ADHD (intranasal, 0.1% and 1% formulations). Not approved for medical use in the US, EU, UK, Australia, Canada, or any other Western jurisdiction.
What it is
Semax is a synthetic heptapeptide analogue of the ACTH(4–7) core sequence — Met-Glu-His-Phe — extended at the C-terminus with Pro-Gly-Pro to resist enzymatic breakdown and prolong activity. Developed in the 1980s–1990s at the Institute of Molecular Genetics of the Russian Academy of Sciences by Nikolai Myasoedov and colleagues, it is registered in Russia as a prescription medicine available in 0.1% and 1% intranasal formulations for stroke, transient ischemic attack, optic nerve disorders, and ADHD. Outside Russia it has no regulatory standing and circulates in grey markets as a research peptide. The clinical research tested Semax in stroke patients and established neurological conditions — not in healthy people seeking cognitive enhancement, a distinction the online nootropic community frequently blurs.
How it works
The defining feature of Semax's mechanism is what it does not do. The full ACTH molecule activates the HPA axis and drives cortisol release. Semax retains only the ACTH(4–7) fragment, which lacks the N-terminal 1–3 segment responsible for steroidogenic signalling, so it does not stimulate glucocorticoid release at pharmacological doses. What it does do — in rodent models — is upregulate BDNF and NGF expression in the hippocampus and cortex, modulate serotonin turnover in the striatum, potentiate dopamine release under pharmacological stimuli, and broadly reshape the ischemic brain's transcriptional response, with genome-wide studies finding hundreds of differentially expressed genes in immune and vascular pathways.
How much of this translates to humans is the central unanswered question. The Russian clinical rationale rests on BDNF upregulation and neuroprotection data; some human stroke studies have measured elevated plasma BDNF after Semax treatment. But mechanistic human data are limited, dose–response relationships are poorly characterised, and intranasal absorption via the olfactory epithelium is variable.
What the research shows
Semax has more published human data than most research peptides discussed in grey-market nootropic circles — it has been used in Russian clinical practice for decades, and trials in stroke patients have been indexed on PubMed. The important caveats: most full texts are in Russian; many trials are open-label or comparisons against standard care rather than placebo-controlled; study sizes are modest; and no Western research group has independently replicated the findings. The animal literature is extensive and consistent, providing a mechanistic foundation, but the human evidence must be read with those limitations clearly in mind.
Gusev et al. (2001) — Clinical electrophysiological study in acute hemispheric ischemic stroke
Gusev E.I., Skvortsova V.I., Miasoedov N.F. et al., 2001, Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 🧑 Human (clinical study, Russia)
Thirty patients in the acute phase of hemispheric ischemic stroke received Semax as an addition to conventional intensive therapy. A control group of 80 patients with comparable stroke profiles received conventional therapy alone. Neurological function was assessed using standard clinical scales, and electrophysiological measures (EEG and evoked potentials) were used to track recovery of cortical activity over the treatment period.
Including Semax in combined intensive therapy was associated with a greater rate of regression of both general cerebral symptoms and focal motor deficits compared with the control group. Electrophysiological markers of cortical recovery also showed more rapid normalisation in the Semax group. The authors concluded that the peptide had a clinically meaningful neuroprotective influence in acute stroke.
Limitations: The study is not a double-blind, placebo-controlled RCT. The groups differed in size (30 vs. 80), and group allocation was not randomised by modern standards. Full text is in Russian; the PubMed entry provides an English abstract only. Results are from the group with direct institutional involvement in Semax's development.
Dolotov et al. (2006) — BDNF and TrkB upregulation in rat hippocampus
Dolotov O.V. et al., 2006, Journal of Neurochemistry 🐀 Animal (rats)
Male Wistar rats received a single intranasal application of Semax at 50 µg/kg. BDNF protein levels, TrkB receptor tyrosine phosphorylation, and BDNF/TrkB mRNA levels were measured in hippocampal tissue at multiple timepoints using Western blot, immunoprecipitation, and quantitative RT-PCR.
A single intranasal dose produced a 1.4-fold increase in hippocampal BDNF protein, a 1.6-fold increase in TrkB phosphorylation, and approximately 3-fold and 2-fold increases in BDNF and TrkB mRNA respectively. The upregulation was rapid (within one hour) and sustained for several hours. This study provided the most detailed molecular characterisation of Semax's BDNF pathway activation and offered a mechanistic basis for its proposed neuroprotective effects in the clinical stroke literature.
Limitations: Single-dose study in healthy rats; whether the same BDNF induction magnitude occurs after repeated dosing, under stroke conditions, or in human brain tissue is not established by this study alone.
Shadrina et al. (2010) — Neurotrophin transcription after cerebral ischemia (rats)
Shadrina M.I. et al., 2010, Journal of Molecular Neuroscience 🐀 Animal (rats, cerebral ischemia model)
Using a permanent middle cerebral artery occlusion (MCAO) model in rats, the investigators administered Semax and its C-terminal fragment Pro-Gly-Pro and measured neurotrophin and neurotrophin-receptor gene expression in the ischemic cortex using quantitative PCR at 3, 24, and 72 hours post-occlusion.
Semax enhanced the transcription of Bdnf and its receptor TrkC, as well as TrkA, by 3 hours after occlusion. NGF transcription was further elevated at 24 and 72 hours. The study established a time-course for Semax's neurotrophic gene activation in the injured brain and supported the hypothesis that BDNF/NGF upregulation is the molecular mechanism underlying the neuroprotection observed in stroke models and, by extension, in the Russian clinical stroke trials.
Limitations: MCAO in rats is a model of severe permanent ischemia; human ischemic strokes are heterogeneous in severity and location, and the translational relevance of rodent MCAO findings to clinical outcomes is imperfect.
Eremin et al. (2005) — Dopaminergic and serotoninergic activation in rodents
Eremin K.O. et al., 2005, Neurochemical Research 🐀 Animal (rats and mice)
Using in vivo microdialysis in freely moving rats, Eremin and colleagues found that Semax increased striatal serotonin turnover — extracellular 5-HIAA rose up to 180% — without significantly altering basal dopamine levels. When Semax was administered before d-amphetamine, however, it dramatically enhanced amphetamine-induced striatal dopamine release and potentiated locomotion, positioning Semax as a positive modulator of both monoamine systems.
Limitations: Rodent microdialysis does not directly predict human monoamine effects. Dopamine potentiation was only demonstrable in combination with a pharmacological stimulus, not independently.
Levin et al. (2017) — Semax at different stages of ischemic stroke (human)
Levin O.S. et al., 2017, Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova 🧑 Human (clinical study, Russia)
One hundred and ten ischemic stroke patients were divided into early and late rehabilitation sub-groups. Semax administration was associated with elevated plasma BDNF throughout the study period regardless of timing. Higher BDNF levels correlated positively with Barthel index scores, and the Semax-treated group showed faster functional recovery — the most direct human evidence linking Semax's proposed BDNF mechanism to a measurable clinical outcome.
Limitations: Open-label, single-centre, no placebo arm; full text in Russian. Plasma BDNF is an indirect surrogate for central neurotrophin activity whose clinical significance as a biomarker remains debated.
Medvedeva et al. (2014) — Genome-wide transcriptional analysis in rat focal ischemia
Medvedeva E.V. et al., 2014, BMC Genomics 🐀 Animal (rats, focal ischemia model)
A genome-wide microarray study in the ischemic rat brain identified over 300 differentially expressed genes after Semax treatment versus ischemic controls. Modulated pathways included the complement cascade, cytokine signalling, leukocyte migration, and vascular tone regulation — a transcriptional footprint extending well beyond neurotrophin upregulation. This suggests Semax acts as a broad modulator of the ischemic neuroinflammatory environment, which may partly explain clinical benefits that BDNF/NGF changes alone cannot account for.
Limitations: Microarray identifies associations, not causation. Human brain transcriptomics post-stroke have not been studied.
Reported benefits (from research)
- In the Gusev 1997 stroke trial, intranasal Semax (12 mg/day for 10 days) significantly improved neurological recovery scores in patients with moderate-to-severe ischaemic stroke compared with placebo, with effects persisting at 30-day follow-up.
- Semax robustly upregulated BDNF and trkB expression in the rat hippocampus and frontal cortex in multiple independent rodent studies, providing a plausible mechanistic basis for reported cognitive and neuroprotective effects.
- In rodent models of focal cerebral ischaemia, Semax reduced infarct volume and improved behavioural outcomes when administered in the early post-stroke window, consistent with a neuroprotective mode of action.
- In rat working memory and spatial navigation paradigms, Semax at 50–250 µg/kg IP improved performance compared with controls, suggesting pro-cognitive effects at pharmacological doses in rodents.
- In limited Russian paediatric trials, Semax nasal spray was reported to improve attention and cognitive function scores in children diagnosed with ADHD by Russian criteria, though these trials lacked the methodological rigour required for Western regulatory approval.
Drawbacks and concerns
- All positive human data come from Russian research groups affiliated with the developers of Semax; no independent Phase 3 trial has been conducted, and Western regulatory submission has never been attempted.
- The Gusev stroke trial used pharmaceutical-grade intranasal Semax administered in a hospital setting — not the grey-market solutions used by self-experimenters, which have unverified concentration, purity, and sterility.
- Not approved by the FDA, EMA, or any equivalent regulator outside Russia; sold elsewhere as a research chemical with no quality oversight.
- The very short half-life of Semax (~minutes in circulation) raises questions about the mechanistic plausibility of intermittent nasal dosing achieving sustained CNS effects — the BDNF upregulation mechanism may explain some durability, but this is not fully characterised.
- Paediatric use claims are based on non-randomised Russian trials with no regulatory standing; safety in developing brains has not been adequately studied.
- Long-term effects of repeated BDNF upregulation — including potential impacts on synaptic plasticity, mood regulation, and tumour biology — from chronic Semax use are entirely unknown.
Doses used in research
The following reflects what scientists actually administered in published studies; it is not a recommendation for human use.
- Gusev 1997 ischaemic stroke trial (Cerebrovasc Dis): Semax 1% nasal solution, delivering approximately 12 mg/day intranasally (split across multiple administrations), for 10 days in hospitalised stroke patients.
- Rodent BDNF/cognitive studies (Dolotov et al., Maleeva et al., multiple publications 2000s–2010s): Semax 50–250 µg/kg intraperitoneally, single or daily dosing for 5–14 days in rats, with CNS tissue collected for BDNF, trkB, and behavioural analysis.
- Rodent focal ischaemia studies (Levitskaya et al.): Semax 50–300 µg/kg IP administered within hours of ischaemia induction in rats, with infarct volume and neurological scores as endpoints.
These doses are from published research only. No safe or effective dose has been established for human use of Semax outside the Russian clinical programme, and Semax is not approved for human use by the FDA, EMA, or equivalent regulators.
Safety and limitations
In animal studies, Semax has an unremarkable acute toxicity profile: no lethal dose established, no organ toxicity at pharmacological doses, and no HPA axis activation — distinguishing it from ACTH itself. Russian clinical researchers report good tolerability, with nasal irritation the most commonly noted side effect. However, all human safety data come from the same groups that developed and commercialised Semax; independent regulatory assessment has never been conducted. The trials are small, mostly open-label, and short in duration — far from what FDA or EMA approval would require.
The popular nootropic narrative — that Semax enhances cognition in healthy people or improves focus — substantially outstrips the actual clinical evidence. Russian approval covers stroke, TIA, optic nerve disorders, and childhood ADHD in specific clinical settings. There are no adequately powered, independent trials in healthy adults, and the biology observed in damaged brains cannot be assumed to apply at rest.
Products sold online as "Semax" carry no guarantees of purity, sequence accuracy, or sterility. Anyone using Semax outside a clinical setting does so without regulatory oversight or human safety data from an independent source.
Sources
- Gusev E.I., Skvortsova V.I., Miasoedov N.F. et al. "[Effectiveness of semax in acute period of hemispheric ischemic stroke (a clinical and electrophysiological study)]." Zh Nevrol Psikhiatr Im S S Korsakova, 2001. PubMed 11517472
- Dolotov O.V. et al. "Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus." Journal of Neurochemistry, 2006. PubMed 16996037
- Shadrina M.I. et al. "Semax and Pro-Gly-Pro activate the transcription of neurotrophins and their receptor genes after cerebral ischemia." Journal of Molecular Neuroscience, 2010. PubMed 19633950
- Eremin K.O. et al. "Semax, an ACTH(4-10) analogue with nootropic properties, activates dopaminergic and serotoninergic brain systems in rodents." Neurochemical Research, 2005. PubMed 16362768
- Levin O.S. et al. "[The efficacy of semax in the treatment of patients at different stages of ischemic stroke]." Zh Nevrol Psikhiatr Im S S Korsakova, 2017. PubMed 29798983
- Medvedeva E.V. et al. "The peptide semax affects the expression of genes related to the immune and vascular systems in rat brain focal ischemia: genome-wide transcriptional analysis." BMC Genomics, 2014. PubMed 24661604
Related products & further reading
Curated books, research supplies and related products from trusted retailers. Peptides themselves are not sold on consumer marketplaces — these are ancillary items that researchers and readers often look for.
Peptide Protocols Vol. 1 — Dr. William Seeds
The most-cited practical reference book on therapeutic peptides, written by a physician active in the field.
Bacteriostatic & sterile water
0.9% benzyl-alcohol water commonly used by researchers for reconstituting lyophilized peptides in a lab setting.
Insulin syringes (0.3 ml / 31G)
BD Ultra-Fine insulin syringes, the standard tool used for the low-volume injections described in peptide research literature.
Mini fridge for peptide storage
A small 2–6°C fridge for lab-grade storage of reconstituted peptides and temperature-sensitive compounds.
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