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AMIRAVOResearch Library

Selank vs Semax

Selank and Semax are heptapeptides developed in Russia that share a Pro-Gly-Pro tail but derive from different parent molecules: Selank is an analog of tuftsin, and Semax is an analog of an ACTH fragment 1,2,8. Both have been studied mainly in rodents and in Russian-language clinical reports, and the FDA lists both among bulk substances for compounding about which it has limited or no safety information 9.

Unbranded reference vial illustrating Selank; not an actual product
Selank
Approved outside the US
Unbranded reference vial illustrating Semax; not an actual product
Semax
Approved outside the US

Side by side

FieldSelankSemax
ClassSynthetic heptapeptide, analog of tuftsin 7,8Synthetic heptapeptide, analog of an ACTH fragment 2,3
Origin and structureThr-Lys-Pro-Arg-Pro-Gly-Pro: the tuftsin sequence with Pro-Gly-Pro attached; the FDA lists it as selank acetate (TP-7) 1,8,9Met-Glu-His-Phe-Pro-Gly-Pro: an ACTH(4-7) fragment with Pro-Gly-Pro attached, also described as an ACTH(4-10) analog 1,2,3
Proposed mechanismInhibited enkephalin-degrading enzymes in human serum in vitro 1; changed expression of genes tied to GABAergic neurotransmission in rat frontal cortex (animal data) 6Inhibited enkephalin-degrading enzymes in human serum in vitro 1; increased BDNF and trkB signaling in rat hippocampus (animal data) 2; altered immune-response gene expression in rat ischemia (animal data) 3
Half-lifeNot identified in the sources reviewedNot identified in the sources reviewed
Highest human trial phaseComparative clinical study versus medazepam in 62 patients, published in Russian 5Clinical study in 110 post-stroke patients, published in Russian 4
FDA statusListed by the FDA (as selank acetate, TP-7) among bulk substances for compounding that may present significant safety risks; FDA lacks important information on safety in humans 9Listed by the FDA (as semax, heptapeptide) on the same page; FDA has no, or limited, safety information for the proposed routes 9
Published human outcomesIn 62 patients with generalized anxiety disorder or neurasthenia, anxiolytic effects on psychometric scales were similar to medazepam, and the authors also described antiasthenic and psychostimulant effects 5In 110 post-stroke patients, groups receiving Semax had higher plasma BDNF and a faster rise in Barthel index scores than groups that did not 4
Safety signalsNo safety findings were given in the abstract of the clinical study; the FDA notes it lacks information on safety in humans 5,9No safety findings were given in the abstract of the clinical study; the FDA notes limited safety information 4,9
WADA statusNot individually named in the 2026 Prohibited List text reviewed; class S0 covers substances with no current governmental approval for human therapeutic use, and this was not assessed here 10Not individually named in the 2026 Prohibited List text reviewed; class S0 covers substances with no current governmental approval for human therapeutic use, and this was not assessed here 10
Evidence levelMostly rodent and in vitro data, with one small Russian-language comparative clinical study 1,5,6,7Mostly rodent and in vitro data, with one Russian-language clinical study 1,2,3,4

Selank: what the data says

In the human literature identified, a Russian-language study of 62 patients with generalized anxiety disorder and neurasthenia compared Selank (30 patients) with medazepam (32 patients) and reported similar anxiolytic effects on the Hamilton, Zung and CGI scales, along with antiasthenic and psychostimulant effects for Selank 5. The abstract does not describe blinding or randomization 5.

In rats (animal-only evidence), Selank prevented ethanol-induced memory and attention disturbances and prevented the ethanol-induced rise in BDNF content in the hippocampus and frontal cortex 7. In rat frontal cortex, it changed the expression of 45 of 84 neurotransmission-related genes one hour after administration, and the changes correlated with those produced by GABA, leading the authors to propose allosteric modulation of the GABAergic system 6. A separate rat study of the analog TP-7 reported reduced anxiety-phobic behavior over four weeks 8.

Semax: what the data says

In rats (animal-only evidence), a single application of Semax increased BDNF protein and trkB phosphorylation in the hippocampus, and treated animals made more conditioned avoidance responses 2. In rats with focal cerebral ischemia, transcriptome analysis found that immune-response genes were the most markedly affected by Semax 3.

In a Russian-language study of 110 patients after ischemic stroke, those who received Semax had higher plasma BDNF throughout the study and a faster improvement in Barthel index scores than those who did not 4. The abstract describes subgroups by rehabilitation timing and Semax use but does not state that allocation was randomized or blinded 4. In human serum in vitro, both Semax and Selank inhibited enkephalin-degrading enzymes, which the authors suggested could contribute to their biological activity 1.

Key research differences

  • Parent molecule: Selank is a tuftsin analog and Semax is an analog of an ACTH fragment, each with a Pro-Gly-Pro tail 1,3,8.
  • Shared in vitro activity: both inhibited enkephalin-degrading enzymes in human serum, with a lower IC50 reported for Semax (10 micromolar) than for Selank (20 micromolar) 1.
  • Studied mechanisms in rodents differ: Semax with hippocampal BDNF/trkB signaling and immune-response gene expression 2,3, Selank with GABAergic gene expression and BDNF content after ethanol exposure (animal data) 6,7.
  • Clinical focus differs: the human report on Selank concerns anxiety disorders and neurasthenia 5, whereas the human report on Semax concerns recovery after ischemic stroke 4.
  • Both human reports were published in Russian, and their abstracts do not describe blinding or randomization 4,5.
  • The FDA lists both and states that it lacks important safety information on Selank and has no or limited safety information on Semax for the proposed routes 9.

Where the evidence is limited

Evidence for both compounds is limited 4,5. Most of the data identified come from Russian research groups, the two human reports identified are Russian-language studies whose abstracts do not describe blinding or randomization, and no independent replication was identified 4,5. The rodent studies use different models and are not directly comparable 2,6. No check of regulatory status outside the United States was made in this review.

Frequently asked questions

How are Selank and Semax related?
Both are synthetic heptapeptides ending in Pro-Gly-Pro 1. Selank is a tuftsin analog, whereas Semax is an analog of an ACTH fragment 1,3,8.
Has either been studied in humans?
A Russian-language study of 62 patients with generalized anxiety disorder or neurasthenia compared Selank with medazepam 5, and a Russian-language study of 110 post-stroke patients examined Semax 4. Their abstracts do not describe blinding or randomization 4,5.
What have animal studies reported?
In rats (animal only), Semax increased hippocampal BDNF and trkB signaling 2, and Selank altered expression of GABA-related genes in the frontal cortex 6.
What does the FDA say about them?
The FDA lists both on its page of bulk drug substances for compounding that may present significant safety risks, noting immunogenicity concerns and limited or absent safety information in humans 9.
Are they named on the WADA Prohibited List?
Neither is individually named in the 2026 list text reviewed; whether the general S0 class for non-approved substances applies depends on approval status, which was not assessed here 10.

References

  1. Semax and selank inhibit the enkephalin-degrading enzymes from human serum (in Russian) Bioorganicheskaia Khimiia. 2001
  2. Semax, an analog of ACTH(4-10) with cognitive effects, regulates BDNF and trkB expression in the rat hippocampus Brain Research. 2006
  3. Semax, an analog of ACTH(4-7), regulates expression of immune response genes during ischemic brain injury in rats Molecular Genetics and Genomics. 2017
  4. The efficacy of semax in the treatment of patients at different stages of ischemic stroke (in Russian) Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 2018
  5. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia (in Russian) Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova. 2008
  6. Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission Frontiers in Pharmacology. 2016
  7. Selank, Peptide Analogue of Tuftsin, Protects Against Ethanol-Induced Memory Impairment by Regulating of BDNF Content in the Hippocampus and Prefrontal Cortex in Rats Bulletin of Experimental Biology and Medicine. 2019
  8. Influence of long-term treatment with tuftsin analogue TP-7 on the anxiety-phobic states and body weight Pharmacological Reports. 2006
  9. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2; content current as of 04/22/2026) FDA (Human Drug Compounding). 2026
  10. International Standard: Prohibited List 2026 WADA. 2026

For research use only. Not for human or veterinary use. Not a drug, food, or dietary supplement. This page compares published research and is not medical advice or a recommendation.