Selank

Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro; CAS 129954-34-3) is a synthetic heptapeptide developed at the Institute of Molecular Genetics of the Russian Academy of Sciences. It was designed as a metabolically stable analogue of tuftsin, an endogenous immunomodulatory tetrapeptide, by appending a C-terminal Pro-Gly-Pro tripeptide that confers resistance to rapid proteolytic degradation in plasma.

The compound exerts effects through several converging neurobiological pathways. Radioligand-receptor studies demonstrate that Selank acts as a positive allosteric modulator of GABA-A receptors, altering [3H]GABA binding in a concentration-dependent manner at a site distinct from the benzodiazepine binding pocket. In rat frontal cortex administered 300 mcg/kg intranasally, 45 of 77 examined GABAergic genes showed significant expression changes at 1 hour, and Gabre and Gabrq subunit transcripts increased 16.1-fold and 13.3-fold respectively at 3 hours post-dose.

Selank also dose-dependently inhibits enkephalin-degrading enzymes (enkephalinases) with an IC50 of approximately 15 micromolar, an inhibitory potency exceeding that of reference peptidase inhibitors bacitracin and puromycin. By slowing the hydrolysis of leu-enkephalin, the peptide prolongs endogenous opioid tone at sites linked to anxiety regulation.

Additionally, Selank rapidly elevates BDNF expression in the hippocampus and frontal cortex and normalizes stress-induced perturbations in serotonin, dopamine, and norepinephrine metabolism. Via its tuftsin-derived N-terminus, it modulates IL-6 gene expression and the Th1/Th2 cytokine balance, contributing immunomodulatory and adaptogenic effects that are mechanistically separable from its anxiolytic action.

The most substantive human evidence consists of a single randomized comparative trial published by Zozulia et al. (2008; PMID 18454096) in Zhurnal Nevrologii i Psikhiatrii Imeni S.S. Korsakova. The study enrolled 62 patients meeting DSM-IV criteria for generalized anxiety disorder (GAD) or neurasthenia; 30 received Selank intranasally and 32 received oral medazepam (a benzodiazepine), with anxiety assessed on the Hamilton Anxiety Rating Scale, the Zung Self-Rating Scale, and the Clinical Global Impression scale. Both treatments produced comparable reductions in anxiety scores. Selank additionally showed antiasthenic and mild psychostimulant effects not seen with medazepam, and was not associated with sedation or cognitive impairment. Critical limitations apply: the trial lacked a placebo arm, was small in sample size, was published only in Russian, and has not been independently replicated in Western journals. On the basis of this trial, Selank received regulatory approval from the Russian Ministry of Health in 2009 for GAD, neurasthenia, and adjustment disorders.

A 2008 study by Uchakina et al. (PMID 18577961) examined 14-day Selank therapy in patients with anxiety-asthenic disorders and demonstrated measurable shifts in Th1/Th2 cytokine balance and IL-6 expression, confirming immunomodulatory effects in a clinical population but not addressing primary anxiolytic or cognitive endpoints.

Preclinical evidence is more extensive. Kasian et al. (2017; PMC5322660) found that Selank (300 mcg/kg intranasal) combined with diazepam (1 mg/kg oral) over 14 days in rats subjected to unpredictable chronic mild stress produced anxiolytic effects 8.9-fold greater on open-arm time versus saline controls, exceeding either drug alone. A separate rodent study (PMID 31625062) found Selank at 0.3 mg/kg for 7 days prevented ethanol-withdrawal-induced memory disturbances and normalized BDNF dysregulation in hippocampus and frontal cortex.

No large-scale, placebo-controlled RCTs have been published in peer-reviewed Western literature. The overall human evidence base is narrow and should be interpreted with caution.

Typical dosage: 250-500 mcg (daily).

The only registered clinical formulation is Selank 0.15% nasal drops, marketed in Russia by ZAO Peptogen and delivering approximately 150 mcg per drop actuation. Russian clinical protocols, as reported in the context of the Zozulia 2008 trial, employed intranasal administration in 14-day treatment courses; precise per-dose microgram amounts are not detailed in the published abstract, but descriptions in the pharmacological literature cite 250-300 mcg three times daily intranasally as the standard therapeutic regimen.

Animal studies in the peer-reviewed literature used 300 mcg/kg intranasally in rats over 14 days; this dose was reported as the most effective in prior dose-finding work. One neuroprotection study used 0.3 mg/kg (300 mcg/kg) intraperitoneally for 7 days.

Outside Russia, Selank is not approved by the FDA or EMA and is available only as a research chemical or through compounding pharmacies. Community and practitioner reports commonly describe intranasal doses of 250-500 mcg per session, given once to twice daily in 10-14 day cycles, with off-cycle periods of equal or longer duration. Subcutaneous injection at similar microgram doses has also been described in community settings, though no published human pharmacokinetic or dosing data exist for the injection route.

This information is provided for educational and research reference purposes only and does not constitute medical advice. Selank is not approved for therapeutic use outside Russia and Ukraine, and any clinical application should occur only under the supervision of a licensed medical professional.

Lyophilized (before reconstitution)

Multiple vendor sources cite roughly the same profile as Semax (related Pro-Gly-Pro-stabilized Russian peptide): ~24 months at −20°C, ~12 months at 2–8°C, and up to ~6 months at room temperature if sealed and dry. Keep away from light and humidity.

Reconstituted

Vendor sources show the same wide 7–28 day spread as Semax refrigerated (2–8°C) in bacteriostatic water, depending on the source consulted. Never freeze. Because the disagreement across sources is larger, this should be treated as lower-confidence guidance than the more consensus-driven peptides in this tier. This is a vendor-derived convention rather than a peptide-specific stability study — the window traces to the 0.9% benzyl alcohol preservative's antimicrobial validation, not to a Selank-specific assay. See the Storage & handling primer for context.

For general storage chemistry (bacteriostatic vs sterile water, freeze-thaw, BUD framework), see Storage & handling.

Last reviewed: July 1, 2026

The most commonly cited combination in the Russian peptide research community is Selank paired with Semax, another synthetic peptide developed at the same institution (Institute of Molecular Genetics). The pharmacological rationale is complementarity: Semax is reported to act primarily via BDNF upregulation and ACTH-fragment neuropeptide signaling, producing stimulatory and focus-enhancing effects, while Selank provides GABAergic stabilization and anxiolysis. The combination is described by community users as producing a state of calm cognitive engagement. No controlled human trials of this combination have been published; the evidence is entirely anecdotal and based on community self-reports.

In the preclinical literature, Selank combined with diazepam in rats (Kasian et al., 2017; PMC5322660) produced synergistic anxiolytic effects greater than either compound alone, with the proposed mechanism being that Selank increases the affinity of diazepam for GABA-A receptors. Some practitioners have extrapolated this to adjunctive use during benzodiazepine tapering, but no human data support this specific application.

Selank combined with phenazepam has been referenced in Russian preclinical literature as well, again showing enhanced anxiolysis, though published human data for this pairing are absent.

Selank is not currently FDA-approved for any indication. It is generally classified as a research compound. Regulatory status varies by country.

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Reported side effects: Very well-tolerated. Rare: mild drowsiness

Published clinical trials of Selank have reported no significant adverse effects, and the compound's documented absence of sedation, muscle relaxation, cognitive impairment, and dependence liability is a consistently cited distinction from benzodiazepines. The Zozulia et al. 2008 trial (n=62) does not detail adverse events in its published abstract. No cases of tolerance, withdrawal syndrome, or physiological dependence have been described in the peer-reviewed literature.

Because Selank is composed solely of natural amino acids, its metabolic breakdown is expected to produce non-toxic peptide fragments, a theoretical safety advantage noted in the primary literature. However, long-term human safety data are essentially absent; the longest available human exposure data derive from 14-day clinical courses.

Anecdotal and post-marketing reports associated with the Russian 0.15% nasal spray include transient nasal irritation, sinus discomfort, mild headache, dizziness, and fatigue. Subcutaneous injection in research contexts outside Russia may produce localized pain, bruising, or swelling at the injection site.

No formal contraindications appear in the published literature, which reflects the limited scope of existing research rather than confirmed broad safety. Insufficient data exist for use in pregnancy, breastfeeding, or pediatric populations. The compound is not scheduled under international narcotics conventions (INCB/UN). Practitioners monitoring off-label use have recommended vigilance for blood pressure fluctuations, nausea, flushing, and cardiac irregularities, though these potential effects have not been confirmed in trial data.