Selank: What It Is, Does It Work, and Is It Safe?

What is Selank?

Selank is a heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. The first four amino acids are tuftsin, a small peptide cut from an antibody that takes part in immune signalling, followed by the same Pro-Gly-Pro tail that Semax has ^[1]. It was developed in Russia as a peptide anxiolytic, a calming drug that is not a benzodiazepine.

How does Selank work?

• Enkephalins. People with generalized anxiety had a shorter enkephalin half-life in their blood. Selank inhibited the enzymes that break enkephalins down, and the authors proposed this as the reason it calms ^[2]. Blocking opioid receptors with naloxone changed its effect in mice, which points the same way ^[3].
• GABA. In rats it changed the expression of dozens of genes involved in GABA signalling within an hour, in a pattern that correlated with GABA itself ^[4]. A later paper proposed that it acts as an allosteric modulator of GABA receptors, at a site different from where diazepam binds ^[5].
• Monoamines. In mice it changed noradrenaline, dopamine and serotonin metabolites, and the direction depended on the strain: anxious mice responded differently from calm ones ^[6].
• Immune signalling. In patients with anxiety it shifted cytokine balance over a 14-day course ^[7].

Does Selank work? The anxiety trials

So in the studies that exist, yes, it reduced anxiety. Read the limits before you rely on that: three trials, about 190 patients in total, all Russian, none compared against a placebo in the abstract, and no independent replication. A Belgian control laboratory described Selank as a research peptide that, to its knowledge, has not completed any clinical trials ^[11].

How long does Selank take to work, and how long does it last?

There is no proper onset study. Two findings give a rough picture:

• Minutes. In 52 healthy volunteers, brain scans showed changed connectivity of the amygdala, the anxiety centre, at 5 and 20 minutes after Selank ^[12]. That is a change on a scan, not a measured drop in anxiety.
• Days after stopping. In the 60-patient trial the anti-anxiety effect lasted for a week after the last dose ^[9].

The published courses ran for about two weeks ^[7]. I found no PubMed abstract with human pharmacokinetics, so there is no verified half-life.

Selank side effects: is it safe?

The trial authors describe it as lacking the side effects typical of most anxiolytics ^[2], and in the add-on trial it reduced sedation, memory impairment and other benzodiazepine side effects instead of adding to them ^[10]. None of the abstracts reports dependence or withdrawal.

What is missing matters more:

• No abstract gives a table of adverse events with numbers.
• No long-term data.
• No data in pregnancy, in children, or alongside antidepressants.
• It acts on the immune system as well as the brain, and the long-term meaning of that is unknown.
• Outside Russia it is sold as a research chemical with no control of purity ^[11].

Selank is not approved by the FDA or the EMA.

Selank vs Xanax and other benzodiazepines

There is no trial of Selank against alprazolam (Xanax). The comparisons are with two other benzodiazepines, medazepam and phenazepam, and in those its effect on anxiety was similar without the sedation. In rats, Selank added to diazepam worked better against chronic stress than either alone ^[13]. The details, and why this is not a reason to swap a prescription on your own, are in Selank vs Xanax.

What dose was used in the studies?

The English abstracts of the clinical trials do not state the dose. In Russia it is used as a nasal preparation. I will not repeat dosing charts from vendor sites, because I cannot trace them to a study.

Selank vs Semax

Selank is the calming one, studied for anxiety. Semax is the stimulating one, studied for stroke recovery and cognition. See Semax vs Selank and the Semax guide.