Research guide
September 16, 2026
Semax and Selank are both synthetic heptapeptides (chains of seven amino acids) developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, and both end in the same stabilizing Pro-Gly-Pro sequence. The core difference in any Semax vs Selank comparison is the parent molecule: Semax is modelled on a fragment of adrenocorticotropic hormone (ACTH), while Selank is modelled on tuftsin, a short peptide derived from immunoglobulin G.
That difference shaped the research: Semax has mostly been studied in brain ischemia models and stroke, Selank in anxiety research. Both are used as medicines in Russia, neither is approved by the US Food and Drug Administration (FDA), and most published evidence comes from Russian groups, often in Russian-language journals or animal models.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is described as an analogue of ACTH(4-10), the fragment of adrenocorticotropic hormone that earlier research identified as the shortest piece retaining the hormone’s behavioural effects in animals, without its hormonal activity. Semax keeps the first four residues of that fragment and replaces the last three with Pro-Gly-Pro, a glyproline sequence that resists breakdown by peptidases.
According to a review by its developers, a team led by N.F. Myasoedov and I.P. Ashmarin began this work in the late 1970s. In their animal behaviour tests, the natural fragment’s effect lasted 30 to 60 minutes while Semax’s lasted 20 to 24 hours, and Semax showed neither corticotropic nor melanocyte-stimulating activity.
Regulatory status: Semax is used in clinical practice in Russia, where it has been studied in stroke and other cerebrovascular conditions. It is not an FDA-approved drug and is not authorized by Health Canada for human or veterinary use.

Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its first four residues are tuftsin, a tetrapeptide from the Fc region of the immunoglobulin G heavy chain, isolated in 1970 and known in immunology for activating phagocytic cells. As with Semax, Pro-Gly-Pro was added to the C-terminus to improve metabolic stability and extend the duration of activity.
Selank was created at the Institute of Molecular Genetics of the Russian Academy of Sciences in cooperation with the V.V. Zakusov Research Institute of Pharmacology. Its developers report that a Selank medicine passed preclinical and clinical testing and was registered by the Russian Ministry of Health in 2009, for use in generalized anxiety disorder and neurasthenia.
Like Semax, Selank is not approved by the FDA and is not authorized by Health Canada. Flux Peptides does not stock Selank; it appears in this guide only for comparison.

The two peptides share a design strategy rather than a mechanism. Each takes a short natural regulatory peptide and adds Pro-Gly-Pro for stability, but the parent molecules point research in different directions.
One small human study did compare them directly: a Russian brain imaging study in 52 healthy volunteers that measured resting-state connectivity, not clinical outcomes.

This summary covers published structure, research and regulatory facts only.
| Feature | Semax | Selank |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent peptide | ACTH(4-10), with its last three residues replaced by Pro-Gly-Pro | Tuftsin (Thr-Lys-Pro-Arg), extended with Pro-Gly-Pro |
| Main research models | Rat ischemia and BDNF studies, Russian stroke studies | Rodent anxiety models, Russian anxiety disorder studies |
| Status in Russia | Used in clinical practice | Registered by the Ministry of Health in 2009 |
| FDA or Health Canada approval | None | None |
| Available from Flux Peptides | Yes, for laboratory research only | No |
The evidence for Semax comes from very different types of study.
None of these findings establishes an effect in people, and Semax has no approved medical use in Canada or the United States.
Medicine status in Russia does not carry over to other countries. Neither Semax nor Selank is an FDA-approved drug. When both were nominated for use by US compounding pharmacies, the FDA listed a possible risk of immunogenicity (an unwanted immune response) linked to peptide aggregation and impurities, and said it lacked adequate human safety information. Those nominations were later withdrawn.
In Canada, neither peptide is authorized by Health Canada for human or veterinary use. Our guide to whether peptides are legal in Canada outlines the general framework; for a specific situation, consult qualified legal counsel.
Flux Peptides supplies Semax research peptide vials for laboratory research. It does not stock Selank. Every batch is assayed by HPLC against a minimum 99.0% purity specification, each order carries a batch identifier, and customers can email fluxpeptides@gmail.com with their order number and batch ID to request that batch’s analysis. Our guide to peptide purity testing explains how to read the results.
Lyophilized stock is sealed, held at minus 20 degrees Celsius and dispatched from within Canada. For handling, see how to store peptides. Flux does not publish dosing information of any kind, and its products are not for human or veterinary use. You can also browse the full research catalogue.
No. Semax is not an FDA-approved drug, and it is not authorized by Health Canada. It is used as a medicine in Russia. When it was nominated for use in US compounding, the FDA noted a possible immunogenicity risk and said it lacked sufficient information to know whether it would cause harm in humans.
In rat studies, Semax has been associated with higher hippocampal BDNF and with changes in immune and vascular gene expression after experimental brain ischemia. It has been studied in stroke patients in Russia, but an independent review found few well-conducted published human studies. These are research observations, not established effects in people.
In Russia, Semax is used in clinical practice, particularly in stroke care. In Canada and the United States it has no approved medical use and is supplied only as a research compound for laboratory work on ACTH-derived peptides, neurotrophin signalling and ischemia models. Flux Peptides does not publish dosing or usage protocols.
Direct comparisons are scarce. One Russian study of 52 healthy volunteers compared Semax, Selank and placebo using resting-state brain MRI and reported both shared and distinct effects on connectivity between the right amygdala and temporal cortex. It did not measure clinical outcomes, and no large comparative trials were found.
Flux Peptides supplies Semax strictly for laboratory research. It is not approved by Health Canada for human or veterinary use, and nothing in this article is medical advice.