COGNITIVE & NOOTROPIC / FAQ
Questions From the Literature
Direct, citation-anchored answers to the questions readers most often bring to these two cognitive research peptides.
What is Selank?
Selank is a synthetic heptapeptide — seven amino acids — derived from tuftsin, a naturally occurring fragment of immunoglobulin G with immunostimulatory properties. The sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro is tuftsin extended at the C-terminus with Pro-Gly-Pro to slow enzymatic degradation and improve metabolic stability. It is catalogued as TP-7 and described as a tuftsin analogue in the literature [1]. It is not an approved drug in the US or Europe; outside Russia it is sold only as a research chemical [6].
What does Selank do?
In animal and limited human research, Selank reduces anxiety, modulates mood, and may support cognition without the sedation or dependence associated with benzodiazepines [6]. Its mechanisms include positive allosteric modulation of GABA receptor binding [1], inhibition of enzymes that break down endogenous enkephalins [7], induction of BDNF expression in the hippocampus [4], and modulation of the Th1/Th2 cytokine balance [5]. A small Russian clinical study reported anxiolytic effects in patients with generalized anxiety disorder comparable to a benzodiazepine comparator [6]. Community users frequently describe reduced situational anxiety, calm without sedation, and a mild focus effect — though these are anecdotal, not clinical evidence.
What is Selank peptide used for?
In Russia, Selank has been used clinically for anxiety-related and neurasthenic disorders, and a clinical study specifically examined it in generalized anxiety disorder [6]. In research settings, it is studied for anxiolytic effects, mood modulation, immunomodulation, and cognitive support. Outside Russia it is not approved for any medical use and is classified as a research chemical. It is not a supplement, not an approved drug, and not intended for human consumption outside a research context. This site does not recommend or advise on any use.
How does Selank work?
Selank's anxiolytic effects are attributed to two primary non-benzodiazepine mechanisms. First, it acts as a positive allosteric modulator of GABA receptor binding — enhancing how GABA binds to its receptor in a subtype-selective, concentration-dependent way [1], and shifting gene expression in GABAergic-pathway genes in rat frontal cortex [3]. Second, it inhibits the enzymes (enkephalinases) that normally break down endogenous enkephalins in human plasma, thereby extending the half-life of those natural anxiety-calming opioid peptides [7]. It also modulates BDNF expression in the hippocampus [4] and the Th1/Th2 cytokine balance [5], suggesting effects beyond the purely anxiolytic.
What is Semax?
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It combines the ACTH(4-7) fragment of adrenocorticotropic hormone with a C-terminal Pro-Gly-Pro tail to slow degradation. Crucially, it lacks the steroidogenic (cortisol-releasing) activity of full-length ACTH. In the research literature it is also catalogued as ACTH(4-7)PGP and MEHFPGP [10]. It is a prescription medicine in Russia and Ukraine for ischemic stroke and cognitive impairment; in the United States it is an unscheduled research chemical [9].
What is Semax peptide used for?
In Russian and Ukrainian clinical practice, Semax is used for ischemic stroke, transient ischemic attack, optic-nerve disease, and cognitive impairment. In research, it is studied primarily for neurotrophin upregulation (BDNF and NGF induction in rodent brain) [10][11], neuroprotection in cerebral ischemia models [9][12], and nootropic effects. A 2025 study documented protective effects in mouse spinal cord injury via an opioid-receptor-linked mechanism [8]. There are no published Western randomized controlled trials for any indication. Community users report focus, mental clarity, and mood lift — but these are anecdotal, not clinical evidence.
Is Semax a peptide?
Yes. Semax is a synthetic linear heptapeptide — a chain of seven amino acids: methionine, glutamic acid, histidine, phenylalanine, proline, glycine, and proline (one-letter code MEHFPGP). It is commonly supplied as the acetate salt. It is not a hormone, not a steroid, and not a growth factor; it is a small peptide that acts on neurotrophin signaling pathways and, in injury models, on immune and vascular gene expression [9][10][11]. As a synthetic research peptide it is not an approved drug in the United States or Europe.
How does Semax work?
The best-characterized effect of Semax in rodents is rapid, region-specific induction of the neurotrophins BDNF and NGF. A single intranasal dose raised NGF and BDNF mRNA in the hippocampus and BDNF in the brainstem, while NGF fell in frontal cortex — a pattern that is gene- and region-specific, not a global surge [10]. A companion study identified a specific, reversible, calcium-dependent binding site with KD 2.4 nM and confirmed a rapid rise in BDNF protein in rat basal forebrain [11]. In ischemia models, its protection is dominated by immunomodulatory and vascular gene-expression shifts [9]. It also inhibits enkephalin-degrading enzymes in human serum in vitro and modulates monoaminergic signaling in rodents [8].
Are Selank and Semax the same thing?
No. Selank and Semax are distinct synthetic heptapeptides with different amino-acid sequences, different parent molecules, and different primary mechanisms. Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) is a tuftsin analog whose primary documented effects are anxiolytic via GABAergic and enkephalin-stabilizing mechanisms [1][7]. Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is an ACTH(4-7) analog whose primary documented effects are neurotrophin upregulation and neuroprotection in injury models [10][11]. They share only the C-terminal Pro-Gly-Pro metabolic stabilizer and their Russian research origin. Their pharmacology is categorically different.
Is Selank or Semax FDA-approved?
Neither compound is FDA-approved for any indication, and neither has EMA approval. Selank has regulatory registration in Russia only, where it has been used clinically for anxiety-related disorders [6]. Semax is a registered prescription medicine in Russia and Ukraine for ischemic stroke, TIA, and cognitive impairment; outside those jurisdictions it is a research chemical [9]. In the United States, both compounds are sold only as unscheduled research chemicals. They are not approved medicines, not dietary supplements, and not intended for human consumption outside a research context.
What are the main differences between Selank and Semax in the research?
Their research profiles reflect their different parent molecules. Selank's evidence concentrates on anxiety, mood, and immune modulation — it is described as an anxiolytic with GABAergic and enkephalin-based mechanisms, and it has a small human dataset in anxiety patients [6]. Semax's evidence concentrates on neurotrophin induction and neuroprotection in ischemia and injury models — its most replicated finding is rapid BDNF and NGF upregulation in specific brain regions [10][11]. In community use, Selank is more often taken for anxiety and social situations, while Semax is more often described as a focus and clarity nootropic. Neither characterization is clinically validated; both are anecdotal alongside a largely regional evidence base.