What have studies of Selank found? Human, animal and cell results

Evidence limits

What have studies of Selank not shown?

The people behind the studies matter too. Each of the four lists N. F. Myasoedov among its authors, and a 2016 paper from the same group says Selank 'was designed and produced at the Institute of Molecular Genetics, Russian Academy of Sciences' (Volkova et al., Frontiers in Pharmacology, 2016). That does not make the results wrong. It means the peptide's developers took part, and no independent replication was found in PubMed.

The numbers are small. The largest patient group in any abstract is 70 people, split into arms of 30 and 40 (Medvedev et al., 2015). Most Selank work is in rats, mice and cells, and the sections below keep those models apart from the patient studies.

What do the human studies of Selank report?

In 62 patients with generalised anxiety disorder (GAD) and neurasthenia (a diagnosis marked by fatigue and weakness), Selank (30 patients) and medazepam (32) had similar anxiolytic effects on the Hamilton, Zung and Clinical Global Impression scales, and Selank also showed antiasthenic (against weakness) and psychostimulant effects; the abstract gives no scale scores and no placebo group (Zozulia et al., *Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova*, 2008). In 60 patients with phobic-anxiety and somatoform disorders, a 2014 study against phenazepam reported 'pronounced anxiolytic and mild nootropic' (thinking and memory) effects, again without scores or a placebo group in the abstract (Medvedev et al., 2014).

In 70 patients with anxiety disorders, 30 given phenazepam alone and 40 given phenazepam with Selank, the abstract says phenazepam's own effect on the Hamilton Depression Rating Scale appeared earlier in the combined group, and that phenazepam's side effects, such as sedation and attention and memory impairment, were lower in the combined group; the abstract gives no scores, reports no placebo group and tests a combination, not Selank alone (Medvedev et al., Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova, 2015).

The abstracts do not print the scale scores or p-values behind 'similar' and 'pronounced', so the size of any difference stays unknown. The same limit applies to the 2008 blood-marker study, which followed patients for 14 days and gives no patient count in its abstract (Uchakina et al., 2008). The table below lists the five human-participant studies found.

How does Selank work in the body, according to research?

Research describes three mechanisms, each seen in laboratory, tissue or animal work and not confirmed in patients. In a laboratory test on human serum, Selank blocked the enzymes that break down enkephalins (the body's own pain and stress peptides) in a concentration-dependent way, a result in serum, with no count in the abstract, that does not establish a human result (Kost et al., 2001). In a radioligand binding study on isolated brain cell membranes, Selank affected GABA binding as a positive allosteric modulator, meaning it can strengthen a receptor's response without sitting on the main site, a laboratory finding with no count in the abstract that does not establish a human result (Vyunova et al., 2018). In rat frontal cortex, 29 genes met the study's change criteria one hour after Selank and 17 did so at three hours, with ten rats assigned per group, five sampled at each time point and tissue pooled; these are animal gene measurements, not clinical outcomes, and they do not establish a human result (Volkova et al., Frontiers in Pharmacology, 2016, Table 1).

Your body breaks enkephalins down quickly, so slowing the enzymes that do it is one way a peptide could change mood signals. In blood plasma, patients with various anxiety and phobic disorders had a shorter enkephalin half-life in generalised anxiety, with no patient count in the abstract, and Selank slowed enkephalin breakdown in plasma in a concentration-dependent way in the laboratory test, with no clinical outcome measured (Zozulya et al., Bulletin of Experimental Biology and Medicine, 2001).

Other findings fit the same picture without settling it. In rats, with no abstract available and so no count checked, Selank changed BDNF (brain-derived neurotrophic factor, a protein that supports nerve-cell growth) expression in the hippocampus, an animal finding that does not establish a human result (Inozemtseva et al., Doklady Biological Sciences, 2008). A nasal 'spray' is a delivery route, not a separate compound, as the Selank and Semax page sets out.

How soon do studies of Selank record a change?

No human study found for this page measured how quickly Selank changes symptoms. The closest timing data come from a 2020 imaging study of 52 healthy people, whose brain scans were taken before and 5 and 20 minutes after Selank, Semax or placebo and showed group differences in connectivity between the right amygdala (a brain region involved in regulating anxiety) and the right temporal cortex; this is a scan measure and does not report how anyone feels (Panikratova et al., Doklady Biological Sciences, 2020). In rat frontal cortex, 29 genes met the study's change criteria one hour after Selank and 17 did so at three hours, with ten rats assigned per group, five sampled at each time point and tissue pooled; these are animal gene measurements, not clinical outcomes, and they do not establish a human result (Volkova et al., Frontiers in Pharmacology, 2016, Table 1). The word 'immediately' has no support in these records.

Timing in longer studies is counted in days. In a four-week experiment in 24 Wistar rats in three groups, anxiety-phobic scores were lower from the second day and the effect held through week four, a result in rats only that does not establish a human result (Czabak-Garbacz et al., Pharmacological Reports, 2006). In patients, the 2014 comparison with phenazepam, in 60 patients with phobic-anxiety and somatoform disorders and with no placebo group reported in its abstract, says the anxiolytic effect lasted a week after the last administration of the peptide (Medvedev et al., 2014). The Selank pharmacokinetics page lines these time points up beside what is known about blood levels.

Have studies found that Selank affects sleep?

No sleep-outcome study of Selank was found in PubMed on 14 October 2026. Only three records pair Selank with sleep terms in the title or abstract, and none measured sleep as a result for Selank itself. A 2016 rat study found that the Hcrt gene, which codes for the precursor of orexin (a brain signal that helps regulate sleep and wakefulness), changed three hours after Selank, and its authors suggest this may explain why Selank lacks the hypnosedative (sleep-inducing and sedating) action of benzodiazepines; it is a rat gene reading, with ten rats assigned per group in that study, that does not establish a human result and is not a sleep measurement (Volkova et al., 2016). In the 70-patient comparison in patients with anxiety disorders, phenazepam's longer sleep duration, a listed side effect, was lower in the group given phenazepam with Selank than in the group given phenazepam alone, and the abstract reports no placebo group (Medvedev et al., 2015).

Volkova et al. (2016) mention a 'normalizing effect' of Selank on sleep patterns in patients with GAD in their discussion, and their paper supplies no patient sleep data for it, so it is the authors' statement and not a result. A peptide named for sleep, DSIP, is compared with Selank on the Selank and Semax page.

Does Selank make people tired, sleepy or alert?

Records on how Selank feels are limited to clinician-rated scales and authors' statements. In the 62-patient study of patients with generalised anxiety disorder or neurasthenia against medazepam, Selank showed antiasthenic (against weakness and fatigue) and psychostimulant effects alongside its anxiolytic effect, on rating scales whose scores the abstract does not print (Zozulia et al., 2008). The authors of a 2016 rat gene-expression paper state that Selank lacks the hypnosedative action common to classical benzodiazepines, which is their interpretation of animal data (Volkova et al., 2016). No study read for this page recorded drowsiness or wakefulness as a measured outcome in healthy volunteers, so the records cannot say how a person feels.

A rating scale is not the same as how a day feels. The Russian product label lists only allergic reactions and an unpleasant taste as adverse reactions, with frequency unknown. The Selank side-effects page reads that label and the other safety records in full.

What have studies found about Selank and cortisol?

No human cortisol measurement for Selank was found. In male rats under chronic restraint stress, blood corticosterone (the main stress steroid in rats, the counterpart of human cortisol) rose, and it was lower in rats that received Selank; the study's main outcome was the condition of the colon wall, and it describes a stress model in animals, with no count in the abstract, that does not establish a human result and is not cortisol in people (Mukhina et al., Bulletin of Experimental Biology and Medicine, 2020). In PubMed, one record pairs Selank with corticosterone or cortisol terms in its title or abstract (searched 14 October 2026).

Can Selank cause dependence or withdrawal symptoms?

No study found measured withdrawal after stopping Selank. The authors of a 2016 paper state that clinical studies show Selank is not accompanied by the amnesia, withdrawal and dependence seen with benzodiazepines, citing Russian papers from 1990 and 1998 that this page did not open, so the statement is the authors' claim and not a result checked here (Volkova et al., 2016). The Russian product label says Selank does not cause drug dependence or habituation. A 2021 review calls Selank poorly studied and says agents with GABA-related action should be evaluated for abuse potential before public access (Doyno and White, 2021).

In rats, Selank was followed by lower signs of morphine withdrawal in a naloxone-precipitated withdrawal model; this is withdrawal from morphine, not withdrawal from Selank, and an animal-only result with no count in the abstract that does not establish a human result (Konstantinopolsky et al., Bulletin of Experimental Biology and Medicine, 2022). In alcohol-preferring rats, the authors report that Selank eliminated anxiety induced by alcohol withdrawal in two behaviour tests; this is withdrawal from alcohol, not from Selank, and an animal-only result with no count in the abstract that does not establish a human result (Kolik et al., 2014).

Does Selank cause weight gain or hair loss?

No human study found records weight gain or hair loss with Selank. A PubMed search on 14 October 2026 for Selank with hair or alopecia in the title or abstract returned no records. The only body-weight result found is from rats: in a four-week study of 24 rats, Selank 'did not cause any changes in the body mass by itself', a rat result that does not establish a human result (Czabak-Garbacz et al., Pharmacological Reports, 2006). The Russian product label lists only allergic reactions and an unpleasant taste as adverse reactions, with frequency unknown. An unrecorded effect is not a ruled-out effect.

Can Selank worsen anxiety?

In rats without chronic stress, courses of Selank or of diazepam shifted anxiety scores on the elevated plus maze (an anxiety test in which rats choose between open and closed arms) in the worse direction, and the shift was smaller after Selank; this is a rat result with no count in the abstract and not a human one (Kasian et al., Behavioural Neurology, 2017). No human study read for this page reports worsened anxiety as an outcome with Selank. In rats under chronic mild stress, the combination of Selank and diazepam returned anxiety scores to their pre-stress values; this is a rat stress-model result for a combination, with no count in the abstract, not a human finding (Kasian et al., Behavioural Neurology, 2017).

Are there published reviews of Selank?

PubMed returned three review-type records with Selank in the title or abstract on 14 October 2026, and none is a systematic review or meta-analysis of Selank trials. They are a 2017 review of tuftsin and its analogues (Siebert et al., Current Medicinal Chemistry, 2017), a 2006 review of anticoagulant effects of proline-containing peptides (Liapina et al., 2006), and a 2026 review of peptides in orthopaedics, which says preclinical results are promising but clinical trials are lacking (Rahman et al., 2026). A 2021 review of GABA-acting sedatives calls Selank poorly studied (Doyno and White, 2021).