selank: the Russian tuftsin-derived heptapeptide studied for anxiety

selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, an extension of the immune peptide tuftsin with a C-terminal Pro-Gly-Pro stabilizer. it was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in Moscow and registered in the Russian Federation in 2009 as an intranasal anxiolytic. it is not approved by the FDA, EMA, MHRA, or TGA.

what is selank?

selank is the natural tuftsin tetrapeptide (Thr-Lys-Pro-Arg) extended at the C-terminus by Pro-Gly-Pro, a glyproline motif the same Russian groups used to stabilize semax. the three proline residues introduce kinks in the backbone, reduce conformational flexibility, and confer relative resistance to many serum proteases that destroy tuftsin within minutes.

tuftsin itself was characterized by Najjar and Nishioka at Tufts University in 1970 as a phagocytosis-stimulating tetrapeptide cleaved from the heavy chain of IgG by leucokininase on neutrophil and macrophage membranes. it is a foundational immunopeptide with documented stimulatory effects on phagocyte activity, but its very short half-life made it impractical as a therapeutic. the Institute of Molecular Genetics (IMG RAS) in Moscow developed selank in the 1990s by appending the Pro-Gly-Pro tail to extend half-life and shift the activity profile toward neurotropic and anxiolytic endpoints rather than tuftsin's classical immune-modulating role [1]. the resulting heptapeptide retains some immune-modulating activity but is studied primarily as an anxiolytic and a cognition-supporting neuropeptide.

selank was registered in the Russian Federation in 2009 under the trade name Selanc as a 0.15 percent intranasal solution for generalized anxiety disorder (GAD) and neurasthenia (asthenic syndromes). a closely related peptide, semax, applies the same Pro-Gly-Pro stabilization strategy to a different parent sequence (ACTH(4-7)) and leans nootropic rather than anxiolytic; the two are often discussed together as a Russian neuropeptide cluster.

how does it work?

selank acts through several systems at once rather than a single receptor. the four most-replicated mechanisms are positive allosteric modulation of GABA-A binding (distinct from the benzodiazepine site), inhibition of enkephalin-degrading enzymes, state-dependent normalization of serotonin turnover, and induction of hippocampal BDNF expression. a fifth lineage-derived pillar is modest immune modulation.

the GABA system interaction is not a classical benzodiazepine mechanism. Vyunova and colleagues characterized selank as a subtype-selective concentration-dependent positive allosteric modulator of [3H]GABA binding on isolated rat brain plasma membranes, with binding sites that partially overlap but are not identical to benzodiazepine sites [2]. in some assays selank can block rather than potentiate diazepam activity, suggesting cross-talk distinct from classical benzodiazepine pharmacology. in rat hippocampus, a single intranasal dose alters transcript levels of GABA-A subunit genes including Gabra3, Gabra5, and Gabrg2, adding a transcriptional layer to the acute receptor interaction [3]. the enkephalin pathway interaction is one of the better-characterized molecular effects. Kost and colleagues at the Mental Health Research Center in Moscow demonstrated that selank dose-dependently inhibits plasma enkephalin-degrading enzymes with IC50 values around 15 to 20 micromolar [4]. inhibition of these enzymes prolongs the half-life of endogenous Leu-enkephalin and Met-enkephalin, increasing endogenous opioid tone in stress-relevant circuits without itself binding opioid receptors. in the Zozulia GAD/neurasthenia patient series, baseline plasma Leu-enkephalin half-life was lower in symptomatic patients and rose toward control values during selank treatment.

the BDNF effect is the most-cited molecular signature. Inozemtseva and colleagues showed that a single intranasal dose of selank (250 or 500 micrograms per kilogram in rats) increases hippocampal BDNF messenger RNA within three hours and BDNF protein within twenty-four hours [5]. that finding has been extended to selank-driven protection against ethanol-induced memory impairment, with BDNF restoration in both hippocampus and prefrontal cortex. the serotonin interaction is state-dependent. under unstressed baseline conditions, 5-HT and 5-HIAA shifts are modest. under stress, PCPA pretreatment, alcohol withdrawal, or chronic mild stress, selank normalizes 5-HT turnover by raising the 5-HIAA/5-HT ratio toward control values. that state-dependence is consistent with the clinical observation that selank reduces anxiety without producing mood-numbing or sedative effects.

what does the evidence show?

the Russian clinical literature centers on small open-label and active-controlled trials in generalized anxiety disorder and neurasthenia, conducted by Zozulia, Medvedev, Seredenin, and colleagues. the most-cited series randomized 62 patients to intranasal selank versus medazepam over 14 days, reporting comparable anxiolytic efficacy without sedation. English-language phase 3 RCTs with modern reporting standards do not exist.

the Zozulia series in GAD and neurasthenia is the foundational clinical dataset. comparable Hamilton Anxiety and Zung-scale reductions to medazepam were reported, but the selank arm also showed anti-asthenic and mild psychostimulant effects that the benzodiazepine arm lacked, and improved plasma Leu-enkephalin half-life correlated with response. a separate active-comparator trial against phenazepam reached similar conclusions: equivalent anxiolytic efficacy with a different tolerability profile, no daytime sedation, no motor slowing, and no documented dependence within the trial period. most published Russian clinical doses fall in the 400 to 900 micrograms per day range, divided across two or three intranasal administrations, for 10 to 14 day courses. preclinical chronic mild stress models in rats report behavioral anxiolysis and the ability to enhance the anxiolytic effect of sub-effective diazepam doses, suggesting a benzodiazepine-sparing combination strategy in research settings [6].

the lineage-derived immune-modulating effects are the second tier of preclinical evidence. selank modulates IL-6 expression in anxiety-asthenic patients (suppressing elevated IL-6) and induces type I interferon without raising TNF-alpha or IL-10. preclinical antiviral activity against influenza A has been reported in cell culture and in vivo, with the strongest signal in prevention-dosing protocols [7]. these findings are mechanistically interesting (tuftsin lineage) but are not an approved indication anywhere and should be framed as translational hypotheses rather than clinical claims. the most important honest caveat is the language gap. the strongest selank clinical data live in Russian journals with English-language indexing typically at abstract level only. no modern multicenter Western-standard double-blind RCT has been published. long-term safety beyond the 10-14 day Russian course regimen is not well characterized in published English literature, and product identity and purity in the US research peptide market are uncontrolled.

regulatory status

selank is registered in the Russian Federation as an intranasal pharmaceutical (Selanc, 0.15 percent nasal drops) for GAD and neurasthenia in adults. it is not FDA approved, not EMA approved, and not currently approved in any Western jurisdiction. WADA does not specifically list selank on the prohibited list as of 2026, although the general "non-approved substances" section can apply where selank is not registered.

the FDA 503A compounding picture is similar to several other community peptides. selank acetate (TP-7) was nominated for 503A bulk drug substance status and placed in Category 2 (do-not-compound) in September 2023. the nomination was withdrawn by the nominator, and selank was removed from Category 2 on September 27, 2024 on procedural grounds rather than as a positive safety determination. it is currently not on Category 1 either, leaving its compounding status unresolved. the Russian formulation is the registered standard: 0.15 percent aqueous selank delivered as intranasal drops, typically two to three times daily during 10 to 14 day courses for the GAD and neurasthenia indications. community use in the US sometimes employs higher concentrations or different intranasal device formats, none of which has been formally compared to the registered formulation.

safety profile and side effects

across the published Russian clinical experience, selank has a favorable acute tolerability profile. no sedation, no motor slowing, no cognitive blunting, no documented dependence within the typical 10-14 day course, and no acute toxicity signal at registered doses. the long-term safety database in chronic use beyond a few weeks is sparse, and product quality in the US research peptide market is uncontrolled.

the favorable acute profile is the main pharmacologic argument for selank versus benzodiazepines. classical benzodiazepines (medazepam, diazepam, phenazepam) produce dose-dependent sedation, motor slowing, anterograde memory impairment, and dependence with chronic use. selank's allosteric and transcriptional mechanism appears to avoid those specific liabilities in the registered Russian experience. the limitations to teach honestly are real. English-language head-to-head RCTs with modern reporting standards are sparse. intranasal pharmacokinetics are highly formulation- and technique-dependent. nose-to-brain transfer measured in rats showed brain content peaking at roughly 0.16 percent of administered radiolabel versus 1.04 percent in plasma, illustrating that only a modest fraction of an intranasal dose reaches the CNS. drug-drug interactions are not formally characterized. theoretical interactions exist with serotonergic agents (selank normalizes 5-HT turnover state-dependently rather than additively) and with benzodiazepines (cross-talk at GABA modulation has been observed in vitro). pregnancy and pediatric data are absent from the published English literature.

where it fits in peptide science

selank sits in the small Russian Pro-Gly-Pro-stabilized neuropeptide cluster alongside semax. both share a stabilizing C-terminal tail strategy, the same Moscow institute lineage, and intranasal administration. they differ in parent sequence and clinical lean: selank is anxiolytic, semax is nootropic.

the most natural comparison is semax, which extends the ACTH(4-7) fragment with the same Pro-Gly-Pro tail. semax has the strongest Russian clinical evidence in ischemic stroke and dyscirculatory encephalopathy, with a different downstream neurotrophin and monoamine profile that supports its nootropic positioning. the two are sometimes stacked in community practice as an "anxiolytic plus focus" combination, though no controlled combination trial has been published.

outside the Russian peptide cluster, selank's closest functional comparators are Western anxiolytics: benzodiazepines, SSRIs, beta-blockers, and the 5-HT1A partial agonist buspirone. each has a different mechanism, time-to-effect, and side-effect profile; selank's distinguishing claims are rapid onset (hours), non-sedating tolerability, and the absence of documented dependence in the Russian clinical experience. those claims rest on a small evidence base that has not been formally replicated in English-language RCTs. for broader context on how regulatory neuropeptides fit into the larger peptide landscape, see our free peptides and your body module and our overview of clinical evidence standards.