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Selank is a synthetic seven-amino-acid peptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) built from tuftsin, a short immunomodulatory peptide, with a Pro-Gly-Pro tail added for stability. It was developed in Russia, where it is approved for the treatment of anxiety1, but it is not an FDA-approved drug2, has no EU centralised authorisation3 and is not named in Australia's Poisons Standard4. The evidence consists mainly of rodent studies and a few small Russian-language clinical trials.
This overview explains what the Selank peptide is, what the laboratory and clinical studies report, and where the evidence runs out. It summarises published research; it is not guidance on use.
Selank is a heptapeptide designed at the Institute of Molecular Genetics of the Russian Academy of Sciences, in cooperation with the Zakusov Research Institute of Pharmacology in Moscow.5 Its first four residues are tuftsin (Thr-Lys-Pro-Arg), a naturally occurring fragment of the heavy chain of human immunoglobulin G. The developers extended tuftsin at its C-terminus with three further amino acids, Pro-Gly-Pro, to improve its metabolic stability and lengthen its duration of action.5
That Pro-Gly-Pro tail is the same "glyproline" unit found on Semax, its sister compound from the same institute. The two peptides are often discussed together, but they are built on different parent molecules; our Semax vs Selank comparison sets out the differences.
Chemical identifiers below are as listed by PubChem.6 Values are for the free peptide; salt forms such as selank acetate have a higher mass per mole.
| Property | Selank |
|---|---|
| Class | Synthetic heptapeptide; tuftsin analogue with a C-terminal Pro-Gly-Pro |
| Sequence (one-letter) | TKPRPGP |
| Sequence (three-letter) | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Molecular formula | C33H57N11O9 |
| Molar mass | 751.9 g/mol |
| CAS number | 129954-34-3 |
| PubChem CID | 11765600 |
| Other names | TP-7 |
| Origin | Institute of Molecular Genetics (Russian Academy of Sciences) with the Zakusov Research Institute of Pharmacology, Moscow |
Put simply, Selank's status as a medicine is Russian; it has no approval in the US or the EU. Research-grade Selank sold for laboratory work is not a medicine in any jurisdiction.
Several mechanisms have been proposed, each resting on a small number of laboratory studies, most from the same Moscow research network.
Enkephalins are short opioid peptides that the body breaks down quickly. A 2001 study reported that Selank inhibited the enzymatic breakdown of enkephalin in human blood plasma in vitro, with a half-maximal inhibitory concentration (IC50) of 15 µM, more potently than the reference peptidase inhibitors bacitracin and puromycin. The same paper reported a shorter enkephalin half-life in the blood of patients with generalised anxiety disorder, and the authors proposed enzyme inhibition as one basis for Selank's reported anxiolytic activity.9 A micromolar IC50 in a test tube is a modest potency, and it does not show that the effect occurs at the concentrations reached in the body.
Benzodiazepines act as positive allosteric modulators of GABA-A receptors. In a 2018 radioligand study on brain membrane preparations, Selank was reported to alter [3H]GABA binding in a way consistent with positive allosteric modulation, and to interfere with the modulatory effects of diazepam and olanzapine. The authors hypothesised subtype-selective, concentration-dependent modulation of GABA receptors as one anti-anxiety mechanism.10
A 2016 study measured 84 neurotransmission-related genes in rat frontal cortex after Selank or GABA. It reported expression changes in 45 genes one hour after administration and 22 genes at three hours, with the changes after Selank correlating with those after GABA.5
Because tuftsin itself acts on immune cells, Selank's immune effects have also been examined. In mouse spleen, a single intraperitoneal injection of Selank was followed by a roughly threefold fall in mRNA for complement component C3 within 30 minutes, along with changes in other inflammation-related genes. The dipeptide fragment Gly-Pro produced similar profiles, which the authors suggested may contribute to Selank's overall effect.11
Anxiety and stress models account for most of the animal work. The table summarises the studies discussed on this page.
| Study | Model | What the authors reported |
|---|---|---|
| Zozulya et al., 20019 | Human plasma, in vitro | Inhibition of enkephalin breakdown (IC50 15 µM) |
| Volkova et al., 20165 | Rats, frontal cortex | Expression changes in 45 of 84 neurotransmission genes at one hour |
| Kasian et al., 201712 | Rats, chronic mild stress, elevated plus maze | Lower anxiety measures, alone and combined with diazepam |
| Vyunova et al., 201810 | Brain membranes, radioligand binding | Positive allosteric modulation of GABA binding |
| Kolomin et al., 201411 | Mouse spleen | Rapid changes in C3 and other inflammation-related genes |
Most Selank animal work relies on a few standard behavioural paradigms. The elevated plus maze measures how much time a rodent spends in open versus enclosed arms of a raised, cross-shaped platform; more open-arm time is read as lower anxiety-like behaviour. Chronic mild stress protocols expose animals to weeks of unpredictable minor stressors, such as altered light cycles or damp bedding, to model a persistent stressed state. Both are widely used, but both are sensitive to handling, strain, time of day and the experimenter, which makes replication across laboratories important.
In the 2017 study, rats were tested in the elevated plus maze with and without a period of unpredictable chronic mild stress, after courses of Selank, diazepam or both. The authors reported that Selank alone was most effective at reducing anxiety measures raised by the repeated handling and administration itself, while the Selank-diazepam combination was most effective under chronic stress.12 The elevated plus maze is a standard rodent anxiety test, but rodent anxiety behaviour is an imperfect proxy for human anxiety disorders.
The human studies of Selank are few, small and published in Russian with short English abstracts. All three below compared Selank with benzodiazepine tranquillisers used in Russia.
A search of ClinicalTrials.gov in September 2026 found no registered trials with Selank as the intervention. There are no large, independent, placebo-controlled trials.
These are preliminary findings. They justify further research, not conclusions about effects in people.
Selank is supplied for in vitro and animal-model work as a lyophilised (freeze-dried) powder, often as the acetate salt. For preparing solutions in the lab, see reconstitution with bacteriostatic or sterile water. Because peptide powders carry counter-ions such as acetate and some residual water, the mass of peptide itself (the net peptide content) is lower than the gross powder weight; a certificate of analysis should say how purity and content were measured, as explained in how to read a peptide COA. Titan Peptides supplies Selank 10 mg for laboratory research only. For the ACTH-derived sister compound, read our Semax research overview.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It is the immune peptide tuftsin extended with a Pro-Gly-Pro tail for metabolic stability. It was designed at the Institute of Molecular Genetics in Moscow with the Zakusov Institute of Pharmacology, and most of its research concerns rodent anxiety and stress models.
No. The Drugs@FDA database contains no product containing Selank. The FDA's compounding safety page, current as of April 2026, lists selank acetate among substances previously placed in category 2 over potential safety risks before the nominations were withdrawn, and says the agency lacks important information about its safety in humans.
Selank is not named in the June 2026 Poisons Standard. Under the Therapeutic Goods Act 1989, goods presented or likely to be taken as being for therapeutic use are therapeutic goods regardless of labelling. Research-grade Selank is not an approved medicine and is supplied for laboratory research only. Our guide to research peptide law in Australia explains more.
Mainly anxiety and stress models in rats, alongside laboratory work on enkephalin-degrading enzymes, GABA-A receptor binding and immune gene expression. In people, three small Russian-language studies compared Selank with benzodiazepines in anxiety-related disorders. None was placebo-controlled and none is registered on ClinicalTrials.gov, so the clinical evidence remains limited.
Tuftsin is a naturally occurring four-amino-acid peptide, Thr-Lys-Pro-Arg, from the heavy chain of human immunoglobulin G. Selank is tuftsin with three more amino acids, Pro-Gly-Pro, added to the C-terminus. The developers added that tail to slow enzymatic breakdown and extend the peptide's duration of action.
Its safety in humans has not been established by large controlled trials. The FDA says it lacks important information about safety issues raised by selank acetate in humans and noted a potential immunogenicity risk. The published clinical studies are small, Russian-language and not placebo-controlled. Titan Peptides supplies Selank for laboratory research only.
Semax and Selank share a Russian origin and the same Pro-Gly-Pro tail, but they are built on different parent peptides and studied in different models. Here is how they compare, study by study.
Semax is a seven-amino-acid ACTH fragment analogue listed as an essential medicine in Russia but not approved in the US or EU. Here is what the rodent and small clinical studies report, and how much weight they can bear.
What bacteriostatic water actually contains, how it compares with sterile water, when benzyl alcohol can interfere, and how to reconstitute a lyophilised peptide and calculate stock concentrations.
