Selank: what the anxiety trials actually tested, and where

Selank is a short synthetic peptide developed in Moscow and sold as an anxiety drug in Russia. Every human study we could find was run in Russia, most by groups that include the peptide’s own developers, and none compared it with a placebo. Those studies report that it eased anxiety about as well as a benzodiazepine without the sedation, which is an interesting claim that nobody outside that network has yet tested.

What selank is

Selank is seven amino acids long: threonine, lysine, proline, arginine, proline, glycine, proline. The first four are tuftsin, a fragment of the antibody molecule IgG that Victor Najjar’s group in Boston described in 1970 as a signal that nudges immune cells to engulf bacteria [1]. On its own, tuftsin breaks down within minutes in blood. Researchers at the Institute of Molecular Genetics in Moscow added a Pro-Gly-Pro tail to make it more stable, the same trick they used for its sister peptide, Semax. The result is described in their papers as the heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro [7].

How it might work is still a set of hypotheses rather than a settled mechanism. Three have been proposed, all from lab work:

• Enkephalin protection. In test tubes, selank slowed the breakdown of enkephalins (the body’s own opioid-like peptides) by enzymes in human blood serum, with a half-maximal effect at about 15 micromolar [6].
• GABA receptor modulation. In membranes isolated from rat brain, selank changed how the calming neurotransmitter GABA bound to its receptors, behaving like a positive allosteric modulator, which is loosely the way benzodiazepines act [7].
• Gene expression changes. In a human neuroblastoma cell line, selank shifted the activity of genes involved in GABA signalling, partly overlapping with the effects of GABA itself [8].

None of these has been shown to explain the clinical effects reported in people.

The human evidence

We found four clinical papers on anxiety and one small brain-imaging study. All were published in Russian journals, and the peptide’s co-developer, N. F. Myasoedov, is an author on most of them.

The 2008 study by Zozulia and colleagues is the one most often quoted. Its abstract says the anxiolytic effects of the two drugs were similar and that selank also had “antiasthenic and psychostimulant” effects [2]. The same team measured how fast enkephalin broke down in patients’ blood and found it was shorter in people with generalised anxiety; selank treatment moved that measure back up [2]. That fits their enzyme theory, but it is a correlation in a small, unblinded group.

A 2014 study by Medvedev and colleagues compared selank with phenazepam (a benzodiazepine widely prescribed in Russia) in 60 people with phobic, anxiety and somatoform disorders [3]. The authors report a “pronounced” anxiolytic effect lasting a week after the last dose. The abstract gives no numbers, no group sizes and no description of blinding.

The 2015 follow-up is the most detailed. Thirty patients took phenazepam alone and 40 took phenazepam plus selank [4]. The combination group improved faster on the Hamilton scale and reported fewer benzodiazepine side effects, including memory and attention problems, sedation and sexual difficulties, both during treatment and after the tranquilliser was stopped [4]. Again there was no placebo, so it’s impossible to say how much of that difference came from the peptide and how much from expectation, since patients and doctors knew who was getting the extra drug.

A smaller 2008 paper looked at immune markers. It reported that 14 days of selank shifted the balance of Th1 and Th2 cytokines in the blood of people with generalised anxiety and neurasthenia [5]. The clinical meaning of that is unclear.

The most recent human work, from 2020, was a brain-scanning study in 52 healthy volunteers who received selank, Semax or placebo [11]. Resting-state MRI showed changes in how the right amygdala connected with parts of the temporal lobe within 20 minutes of dosing. It had a placebo arm, but it measured brain connectivity, not anxiety.

Where the “nootropic” label comes from

Selank is often marketed online as a focus or memory aid. The human basis for that is thin. The 2014 abstract mentions “mild nootropic effects” without saying how they were measured [3], and the 2008 trial describes “psychostimulant” effects in anxious, fatigued patients [2]. The 2015 study used a Stroop test and a verbal fluency task, but its reported cognitive benefit was that people on the combination avoided the memory and attention problems caused by phenazepam [4]. That is a different thing from making a healthy person sharper, and no study we found tested selank on cognition in healthy adults. The memory findings people cite are from rats [10].

Why these trials don’t settle much

Three things limit what these studies can tell you. The first is the missing placebo. Anxiety scores fall in almost every anxiety trial, including in people taking dummy pills, so a drug that performs “about as well” as a benzodiazepine in a small open study might be doing a lot or very little.

The second is who ran them. Almost every paper, clinical and preclinical, comes from a small cluster of Moscow institutes linked to the peptide’s development. That doesn’t make the findings wrong, but independent replication is the usual test, and selank hasn’t had one.

The third is access. The clinical papers are in Russian, and the English abstracts leave out basics such as how patients were allocated, the dose and route, how many dropped out and the actual score changes. We can’t check the effect sizes, so we haven’t reported any.

What the animal and lab work suggests

Most selank research is in rodents. In rats under chronic mild stress, adding selank to diazepam reduced anxiety-like behaviour more than diazepam alone [9]. In rats given alcohol, selank protected against memory problems and changed levels of the growth factor BDNF in the hippocampus and prefrontal cortex [10]. These are standard models, but they measure things like time spent in the open arm of a maze, which doesn’t map neatly onto human anxiety.

The cell and membrane work described above [6–8] shows selank does something biologically. What it doesn’t show is that those effects happen at the doses people use, or that they reach the brain after a nasal dose in humans.

Safety and side effects reported

The Russian trials describe selank as well tolerated, and the 2015 study reports it reduced side effects of phenazepam rather than adding its own [4]. But none of these papers is large enough, long enough or transparent enough to detect uncommon harms. There is no published long-term safety data, no independent pharmacovigilance data we could find, and nothing on use in pregnancy, in children or alongside other psychiatric drugs apart from benzodiazepines.

Products sold online as “research peptides” add another unknown, since there’s no guarantee they contain what the label says or at the stated purity.

Legal and regulatory status

Selank is used as a prescription nasal medicine in Russia. It is not approved as a medicine by the UK’s MHRA, the European Medicines Agency or the US FDA, and we found no registered trials in those regions. In the UK and US it is sold only as a research chemical, which means it isn’t made or checked to medicine standards and isn’t meant for human use.

What we still don’t know

• Whether selank beats a placebo for anxiety in a properly blinded, randomised trial.
• The effect size in any trial, since the published abstracts don’t report the score changes.
• Whether nasal selank reaches the human brain in meaningful amounts.
• Whether any of the lab mechanisms (enkephalin protection, GABA modulation) operate in people.
• Long-term safety, and whether stopping it causes any rebound or withdrawal.
• Whether a research group without ties to its developers can reproduce the findings.

Educational content only — not medical advice. Many peptides discussed on HPR are not approved for human use. Talk to a qualified clinician before making any decision about your health.

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