Sleep, Energy & Cognition
Semax and Selank: What Evidence Exists Outside Russia?
The short answer
A ClinicalTrials.gov search run this session found zero registered trials for either Semax or Selank, under any spelling. On PubMed, the human literature for both peptides is small and almost entirely Russian: a 2007 open-label study tested Semax in 27 patients with motor neuron disease, and a 2008 trial compared Selank to the benzodiazepine medazepam (not placebo) in 62 patients with generalized anxiety disorder and neurasthenia. A 2026 review of peptide therapeutics, describing Semax and Selank alongside other 'neuroactive peptides,' concluded there is 'a current lack of clinical trials.' The evidence base for both compounds is largely non-replicated and comes from one country.
Quick answers
- What is it?
- Semax and Selank are synthetic peptides developed and used clinically in Russia for decades, now marketed internationally for focus, mood, and anxiety.
- Why are people interested in it?
- These peptides are increasingly sold online for cognitive and mood benefits, so buyers outside Russia want to know if there's any independent trial evidence behind them.
- What has actually been studied?
- A ClinicalTrials.gov search for both compounds, a 2007 open-label Semax study in 27 motor neuron disease patients, and a 2008 trial comparing Selank against the benzodiazepine medazepam in 62 patients with anxiety and neurasthenia.
- How strong is the evidence?
- Very weak: zero trials are registered on ClinicalTrials.gov for either compound, the existing human studies are small, unblinded or active-comparator (not placebo-controlled), and come entirely from Russian institutions with no independent replication.
- What don't we know yet?
- Whether either peptide works better than placebo, whether the Russian findings replicate outside Russia, basic pharmacokinetic and safety data by modern trial standards, and what either peptide does for sleep specifically.
- Where can I read the original research?
- Sources at the bottom of this page: Zozulia AA, Neznamov GG, Siuniakov TS, et al., Zhurnal Nevrologii i Psikhiatrii, 2008; and Serdiuk AV, Levitskiĭ GN, Miasoedov NF, Skvortsova VI, Zhurnal Nevrologii i Psikhiatrii, 2007.
The short answer: Semax and Selank are two synthetic peptides — Semax derived from a fragment of ACTH, Selank a synthetic analogue of the immune peptide tuftsin — that have been used clinically in Russia for decades and are now sold internationally, often marketed for focus, mood, and anxiety. A ClinicalTrials.gov search run this session found zero registered trials for either compound, under any name variant. The PubMed record is thin and geographically narrow: the clearest human data located this session were a 2007 open-label Semax study in 27 motor neuron disease patients and a 2008 Selank trial comparing it to a benzodiazepine (not placebo) in 62 patients with anxiety and neurasthenia. Both are Russian studies, published in Russian. A 2026 peer-reviewed review covering both compounds concluded plainly that there is "a current lack of clinical trials." This is not a case of hidden Western data — the trial registry and the literature both point the same direction.
What the research shows
Semax is a synthetic heptapeptide built from a fragment of adrenocorticotropic hormone (ACTH 4-10), developed in Russia in the 1980s and approved there for conditions including ischemic stroke and optic nerve disorders. Selank is a synthetic analogue of tuftsin, an immune-system peptide, developed by the same Russian pharmacological institute and studied there as an anxiolytic. Both are administered intranasally in most published research. Neither has gone through FDA review, and — as the ClinicalTrials.gov search run this session confirmed — neither has a single trial registered in the U.S. system, whether searched as "Semax," "Selank," or their known synonyms.
The clinical literature that does exist comes almost entirely from Russian institutions, published in Russian-language journals, and is small in scale. For Semax, one of the more substantive human studies retrieved this session is a 2007 report in the Zhurnal Nevrologii i Psikhiatrii testing intranasal Semax (1% solution, 12 mg/day) in 27 patients with motor neuron disease. It was an open-label trial — no blinding, no placebo control — run in sequential groups rather than randomized arms. The peptide did not change the underlying pattern of nerve fiber denervation the researchers measured by needle electromyography, but patients' self-reported quality-of-life scores improved, an effect the authors attributed to mood and motivation rather than a disease-modifying action. A separate Russian review from 2016 discussed Semax's proposed neuroprotective mechanism after ischemic stroke, centered on a protein called transthyretin, but this was a mechanistic review of prior work rather than a new clinical trial.
For Selank, the clearest human study located this session is a 2008 trial, also published in the Zhurnal Nevrologii i Psikhiatrii, enrolling 62 patients with generalized anxiety disorder and neurasthenia. Thirty patients received Selank and 32 received medazepam, an existing benzodiazepine — the trial compared the new peptide against an approved drug, not against placebo. The researchers reported similar anxiolytic effects between the two, with Selank additionally showing antiasthenic and mildly stimulant effects, and tracked a blood biomarker (enkephalin activity) alongside psychometric rating scales. Whatever its results, a single 62-patient active-comparator trial from one country is a narrow foundation for the range of claims made about Selank in current marketing.
A 2026 review in JAAOS Global Research & Reviews, surveying therapeutic peptides used in orthopedic and recovery contexts, grouped Selank and Semax together with several other "neuroactive peptides" — alongside DSIP, epithalon, and dihexa — and stated that despite mechanistic interest in pathways like brain-derived neurotrophic factor signaling, "although preclinical studies are promising, there is a current lack of clinical trials." A 2025 review in Neuropeptides, focused on neurodegenerative disease, listed Semax among several bioactive peptides "found to modulate several critical mechanisms" but noted that "future clinical validation" was still needed before translating the preclinical work into treatment. Neither review pointed to trial evidence beyond what's summarized above.
None of this means Semax and Selank have no biological activity — animal and cell-based research on both compounds, not covered in depth here, has explored proposed mechanisms involving neurotrophic signaling and immune modulation. But the specific, narrow claim this article can support with retrieved data is about the human clinical trial base: it is small, it is not placebo-controlled in the trials found, it has not been replicated outside Russia, and it does not currently include a single entry in the primary Western clinical trials registry.
What we don't know yet
Whether either peptide works better than placebo. Neither of the human studies retrieved this session used a placebo control — the Semax study was open-label, and the Selank study compared the peptide to an active drug. No placebo-controlled trial of either compound was found.
Whether the Russian findings replicate outside Russia. Every human study located in this search originated from Russian institutions. No independent research group outside Russia appears to have run a controlled trial of either peptide.
Basic pharmacokinetics and safety data from modern trial standards. With no registered trials on ClinicalTrials.gov, there is no publicly tracked Phase 1 safety, dosing, or pharmacokinetic data for either compound meeting current Western trial registration and reporting norms.
Whether intranasal delivery — the route used in nearly all located studies — behaves the same as the oral or injectable forms sold to consumers today. The retrieved trials used intranasal administration specifically; how other routes perform was not addressed in any study found.
What either peptide does for sleep specifically. Despite being marketed in sleep and cognition stacks, none of the human studies retrieved this session used a sleep-related primary outcome for either Semax or Selank.
Sources
- Zozulia AA, Neznamov GG, Siuniakov TS, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia [Russian]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2008;108(4):38-48. PubMed
- Serdiuk AV, Levitskiĭ GN, Miasoedov NF, Skvortsova VI. The study of chronic partial denervation and quality of life in patients with motor neuron disease treated with semax [Russian]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2007;107(4):29-39. PubMed
- Rahman OF, Lee SJ, Seeds WA. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions. JAAOS Global Research & Reviews, 2026;10(1). DOI
- Giri S, Chandra P. Modulation of neuropathological pathways by bioactive peptides and proteins/polypeptides: Targeting oxidative stress in neurodegenerative diseases. Neuropeptides, 2025;114:102563. DOI
- Vyunova TV, Medvedeva EV, Andreeva LA, Dergunova LV, Limborska SA, Myasoedov NF. Possible role of transthyretin in the biological mechanism of the regulatory peptide neuroprotection [Russian]. Molekuliarnaia Genetika, Mikrobiologiia i Virusologiia, 2016;34(3):104-109. PubMed
Article records maintained via PubMed. Peptide Proof reports what studies found. It does not provide medical advice, dosing guidance, or treatment recommendations.
Topic: Brain & Cognitive Health | Evidence Index: semax · selank
Sources
- Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia
- Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2008 · n=62
- The study of chronic partial denervation and quality of life in patients with motor neuron disease treated with semax
- Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2007 · n=27
- Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.
- JAAOS Global Research & Reviews, 2026 · DOI
- Modulation of neuropathological pathways by bioactive peptides and proteins/polypeptides: Targeting oxidative stress in neurodegenerative diseases.
- Neuropeptides, 2025 · DOI
- Possible role of transthyretin in the biological mechanism of the regulatory peptide neuroprotection
- Molekuliarnaia Genetika, Mikrobiologiia i Virusologiia, 2016
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