Peptide Briefs

Selank

Evidence Grade: C — Approved as a drug in Russia on the strength of small, single-center, Russian-language clinical trials against active comparators rather than placebo. Mechanistic work in rats is reasonable; independent replication outside the developing institutes is essentially absent.

What it is

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro): the natural tetrapeptide tuftsin — a fragment of the IgG heavy chain with immunomodulatory activity — extended with a Pro-Gly-Pro tail to slow enzymatic breakdown. It was developed at the Institute of Molecular Genetics (Russian Academy of Sciences) with the V.V. Zakusov Research Institute of Pharmacology, and is sold in Russia as a nasal spray for anxiety.

Proposed mechanism

Reported mechanisms, mostly from rat and cell studies by the developing group:

  • Allosteric modulation of the GABA-A receptor system — Selank and GABA produced correlated shifts in expression of neurotransmission genes in rat frontal cortex
  • Increased enkephalin half-life in serum (inhibition of enkephalin-degrading enzymes), which the clinical trial authors linked to anxiety reduction
  • Changes in serotonin metabolism and in BDNF expression in animal brain
  • Immune-gene expression shifts, consistent with its tuftsin origin

A cell-culture follow-up found Selank alone did not change GABAergic gene expression in a neuroblastoma line, suggesting the effect in vivo may not be direct.

What the literature shows

Animal: Anxiolytic-like behavior in rodent models without sedation or motor impairment; an additive effect with diazepam under chronic stress; some reports of memory-related effects.

Human: The most-cited trial compared Selank (30 patients) with the benzodiazepine medazepam (32 patients) in generalized anxiety disorder and neurasthenia, using Hamilton, Zung, and CGI scales. Anxiolytic effects were reported as similar, with Selank showing additional anti-asthenic and mild stimulant effects. Later Russian work compared it with phenazepam and reported fewer side effects. These trials used active comparators rather than placebo, were small, and the full methodology is available only in Russian. No Western-registered trials were identified.

Regulatory status

Approved in Russia (2009) as a prescription nasal spray for generalized anxiety disorder and neurasthenia. Not approved in the US, EU, or elsewhere. Not scheduled. Not on the WADA Prohibited List.

Gaps and caveats

  • No placebo-controlled human trial in the English-indexed literature
  • Primary sources are largely Russian-language; abstracts are translated, full methods are not
  • All mechanistic and clinical work comes from two cooperating Moscow institutes
  • Pharmacokinetics beyond the nasal route are poorly described
  • Immune effects are reported in animals but uncharacterized clinically

Key references