PwPepwise

Selank

Brain & Focus

Tuftsin analog

Selank is a synthetic heptapeptide (seven amino acid) anxiolytic developed in Russia, structurally derived from tuftsin.

§Dosing at a glance

3 protocols · from the research
What it's forDoseHow oftenHowFor how long
Animal Studies — Anxiolytic / Withdrawal0.3 mg/kg—IntraperitonealInjected into the abdominal cavity (research use).7 days
Animal Studies — Stress / Gut Protection750 μg/kg———
Animal Studies — Transcriptomic / Receptor Effects200 μg/kg—IntranasalSprayed into the nose.—

Approximate values pulled from the research — double-check before dosing.

§01Summary

Selank is a synthetic heptapeptide (seven amino acid) anxiolytic developed in Russia, structurally derived from tuftsin — a naturally occurring immune-regulating peptide — with an added Pro-Gly-Pro sequence that confers distinct neurological activity. It is designed to reduce anxiety and support cognitive function without the sedative or dependency risks associated with conventional anti-anxiety medications like benzodiazepines.

In clinical studies, Selank has been reported to produce anxiolytic effects comparable to established benzodiazepines such as medazepam and phenazepam in patients with generalized anxiety disorder (GAD) and related conditions1,2. Unlike classic benzodiazepines, it may also provide mild cognitive-stimulating and anti-fatigue (antiasthenic) benefits alongside its calming effects1. Early human research suggests that Selank may help reduce the side effects associated with benzodiazepine use when the two are combined2, and one study reported a residual anxiolytic effect persisting approximately one week after the last dose18. Beyond anxiety, preliminary animal research points to potential benefits including neuroprotection, support for gut health under chronic stress11,15, and cognitive enhancement16 — areas that are actively being studied.

This is the layperson summary. Mechanism, dosing, the evidence base, and the published literature are in the sections below — every claim links to its source.

§02In depth

Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro; TKPRPGP) is a synthetic heptapeptide analogue of the endogenous immunomodulatory tetrapeptide tuftsin (Thr-Lys-Pro-Arg), with an appended C-terminal Pro-Gly-Pro sequence that substantially alters its pharmacological profile and CNS penetrance. The peptide is metabolized in blood plasma primarily into the pentapeptide TKPRP, the tripeptide TKP, and the dipeptides RP and GP4, with intranasal administration confirmed to deliver Selank to brain tissue4.

Selank's anxiolytic mechanism appears to be multifactorial. At the receptor level, it acts as a positive allosteric modulator of GABA-A receptors, enhancing [³H]GABA binding in a concentration-dependent and subtype-selective manner in isolated brain membrane preparations6. Notably, Selank can also block the modulatory activity of benzodiazepines such as diazepam and olanzapine at these receptors, demonstrating a non-cumulative interaction pattern distinct from classical GABAergic drugs6. Route of administration influences downstream receptor engagement: intraperitoneal delivery increases GABA-A receptor binding sites in the frontal cortex by approximately 38%, while intranasal delivery increases NMDA receptor binding density in the hippocampus by approximately 23%, suggesting that biotransformation differences generate metabolites with varying receptor selectivity20.

A second well-characterized mechanism involves inhibition of enkephalin-degrading enzymes (enkephalinases). Selank inhibits enzymatic hydrolysis of plasma enkephalin with an IC50 of 15–20 μM in vitro5,7, substantially outperforming established peptidase inhibitors such as bacitracin and puromycin7. This prolongs endogenous enkephalin activity and may underlie the observed normalization of leu-enkephalin degradation half-life (tau₁/₂) in GAD patients treated with Selank1. Interestingly, shortened enkephalin half-life correlates with GAD severity but not with panic disorder or agoraphobia, suggesting diagnostic specificity for this mechanism5. Pentapeptide fragments of Selank retain enkephalinase inhibitory activity, while tri-, tetra-, and hexapeptide fragments do not, indicating a specific structure-activity relationship7.

At the transcriptomic level, a single administration of Selank significantly alters mRNA expression of 45 genes involved in GABAergic, dopaminergic, and serotonergic neurotransmission within 1 hour, with 22 genes remaining altered at 3 hours9. Gene expression changes show a positive correlation with GABA-induced transcriptional patterns, supporting shared mechanistic pathways9. Hippocampal transcriptomics reveal predominant effects on plasma membrane-associated and transmembrane protein genes — particularly those regulating ion homeostasis — providing a mechanistic basis for reported cognitive effects17. Selank also modulates serotonin metabolism in the brain stem under conditions of serotonin depletion, an effect not shared by its parent peptide tuftsin, attributable to the Pro-Gly-Pro extension19. Monoamine effects are strain-dependent in rodents: Selank increases hypothalamic norepinephrine in both mouse strains tested, but produces opposing effects on dopaminergic metabolites in frontal cortex and hippocampus depending on baseline stress phenotype13. Additionally, Selank regulates BDNF content in the hippocampus and prefrontal cortex, normalizing ethanol-induced BDNF dysregulation16, and modulates inflammatory gene expression in peripheral immune tissue through effects on the transcription factor Bcl610.

§04Evidence & efficacy

Evidence base
130Studies
16Human
45Animal

Selank's most substantiated area of efficacy is the treatment of generalized anxiety disorder (GAD) and related anxiety-spectrum conditions. In the highest-quality study reviewed, Selank demonstrated anxiolytic effects comparable to the benzodiazepine medazepam in patients with GAD and neurasthenia as measured by the Hamilton, Zung, and CGI scales, while also providing additional antiasthenic and psychostimulant benefits not seen with medazepam1. A second RCT found that combining Selank with phenazepam accelerated the onset of anxiolytic effect compared to phenazepam alone, with superior preservation of cognitive performance and quality of life outcomes2. A non-randomized comparison study reported that Selank's anxiolytic effect may persist for approximately one week following treatment cessation18.

An fMRI-based connectomics study in healthy participants found that Selank altered resting-state functional connectivity between the right amygdala and temporal cortical regions, providing objective neuroimaging evidence consistent with its anxiolytic profile3.

In animal models, Selank has been reported to reduce anxiety behaviors in alcohol withdrawal paradigms8, enhance cognitive function in aged rats and protect against ethanol-induced memory impairment16, and demonstrate antidepressant-relevant serotonergic activity in the brain stem19. Immune and gut-related benefits under chronic stress conditions have also been observed in preclinical settings10,11,15.

§05Safety

Selank has been reported to exhibit a favorable tolerability profile relative to benzodiazepines in human clinical studies. In a study comparing Selank combined with phenazepam versus phenazepam alone, the combination group showed significantly reduced phenazepam-associated adverse effects including attention and memory impairment, asthenia, sedation, hypersomnia, sexual disturbances, emotional indifference, and orthostatic hypotension — suggesting that Selank may mitigate rather than exacerbate benzodiazepine-related side effects2. A comparative study with phenazepam reported Selank to be well-tolerated in patients with phobic-anxiety and somatoform disorders, though specific adverse event rates were not quantitatively detailed18. Early mechanistic work noted that Selank does not appear to cause the side effects typical of most conventional anxiolytics5.

In animal studies, course administration of Selank as a standalone agent was associated with a modest worsening of anxiety indicators under non-stress conditions, an effect that was less pronounced than that observed with diazepam12. The in vitro finding that Selank can block the modulatory activity of benzodiazepines such as diazepam and olanzapine at GABA-A receptors6 suggests the potential for pharmacodynamic interactions when co-administered with these agents — a relationship that ongoing research is actively characterizing.

No formal dose-escalation, maximum tolerated dose, or long-term human safety studies are represented in the reviewed literature. Systematic adverse event reporting with quantitative frequency data is an area where the human evidence base is still developing.

§06History

Selank was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and the V.V. Zakusov Institute of Pharmacology, emerging from a research program focused on peptide-based psychopharmacology in the late Soviet and early post-Soviet era. It was rationally designed as a synthetic analogue of tuftsin — a naturally occurring immunomodulatory tetrapeptide fragment of IgG — with the addition of a C-terminal Pro-Gly-Pro sequence to enhance stability and CNS activity.

Early mechanistic research in the 2000s established Selank's enkephalinase inhibitory properties as a proposed basis for its anxiolytic activity, with human serum studies demonstrating potent dose-dependent inhibition of enkephalin-degrading enzymes5,7. Pharmacokinetic characterization using tritium-labeled peptides confirmed intranasal delivery to brain tissue and identified primary metabolic degradation products4.

The first comparative randomized clinical trial, published in 2008, established Selank's anxiolytic efficacy relative to medazepam in GAD and neurasthenia, alongside a distinctive antiasthenic and psychostimulant profile1. Selank subsequently received regulatory approval in Russia as an anxiolytic nasal spray under the brand name Selank. A second RCT published in 2015 explored its use as an adjunct to phenazepam for anxiety-spectrum disorders2.

Subsequent research has broadened the mechanistic understanding of Selank to include GABAergic allosteric modulation6,9, monoaminergic effects13,19, neuroimaging-confirmed amygdala connectivity changes3, BDNF regulation16, and gut-protective properties under chronic stress11,15. The compound remains primarily studied within Russian scientific institutions, with active research ongoing across neurological, immunological, and gastrointestinal domains.

§07References