The short version

Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.

What Selank is

Selank is a seven-residue peptide: tuftsin — Thr-Lys-Pro-Arg, a fragment of an immunoglobulin heavy chain — with Pro-Gly-Pro added. It was built at the Institute of Molecular Genetics of the Russian Academy of Sciences alongside its better-known sibling Semax, which is the same Pro-Gly-Pro tail on a different head. It is a registered, over-the-counter anxiolytic in Russia.

That last row is worth a moment. The Russian medicine's active substance is named on the label as the diacetate, and FDA's own entry is for "selank acetate." A certificate that says only "Selank" has not told you what is in the vial.

N-Acetyl Selank Amidate

A genuinely different molecule — acetylated at one end, amidated at the other — and the chemical rationale for capping a peptide against exopeptidases is real. What does not exist is any evidence about it. We searched the indexed literature for the acetylated or amidated form and found zero studies: not one animal study, not one clinical study, and not the Russian registered medicine, which uses plain Selank diacetate.

We are also not going to print a molecular weight for it. The registry entries are wrong, we could not verify one from any trustworthy source, and a number we calculated ourselves is not a citation. Every claim made for this analogue is borrowed from a different molecule.

How it is said to work

The GABA story — the strongest claim, and it is a test tube

Vyunova and colleagues, 2018, in Protein and Peptide Letters, is the paper behind "Selank modulates the benzodiazepine site." What they measured was tritiated GABA binding to isolated brain-cell plasma membranes. Their finding, verbatim:

Read the second half of that. In this assay Selank blocked diazepam's modulation. That is not "works like a benzodiazepine" — if anything it is the opposite, and it is one of the reasons the authors' own conclusion is hedged to "can be associated with." No cell, no animal, no person.

The BDNF story is a normalisation, not an increase

Kolik and colleagues, 2019, gave rats Selank 0.3 mg/kg a day intraperitoneally for seven days and found it "prevented ethanol-induced increase in BDNF content in the hippocampus and frontal cortex." It brought an elevation back down. It did not raise BDNF in healthy animals, and no study has shown it doing so. "Selank raises BDNF" is a misreading of a normalisation effect in an alcohol model.

The enkephalinase story does not survive the arithmetic

Kost and colleagues, 2001, showed Selank inhibits enkephalin-degrading enzymes in human serum, with an IC₅₀ of 20 µM. That is a real measurement on real human serum, and it is the basis for the whole "endogenous opioid" mechanism you will read about.

Now put a dose next to it. A 900 mcg intranasal dose spread through about five litres of plasma gives a theoretical ceiling near 0.24 µM — and that assumes 100% absorption and zero clearance, of a peptide whose measured half-life is minutes. That is roughly eighty-fold below the concentration at which the enzyme inhibition was observed. The arithmetic is ours and it is simple enough for you to check. On these numbers the enkephalinase mechanism is not plausible at any dose anyone actually uses.

The tuftsin and immune claims

Selank contains the tuftsin sequence, so an immune rationale is structurally reasonable. The evidence is a mouse spleen gene-expression study, one human immunomodulation paper from 2008 whose abstract we could not retrieve, and antiviral claims published by a single Russian group in a single journal with no independent replication anywhere. We are listing them so this page is not accused of hiding them, and we are not building anything on them.

Pharmacokinetics

The famous number is "92.8% bioavailable." It is worth understanding exactly what that figure is, because it is not what it sounds like.

It comes from the registered product's own information leaflet, which states that absolute bioavailability on the nasal mucosa is 92.8%, that the peptide appears in plasma within 30 seconds, and that plasma concentration falls over five to five and a half minutes.

Two minutes, or twenty-four hours?

The developers' own 2013 review gives an in vitro half-life of about two minutes, and in the same document says Selank "acts continuously for 20–24 h." Those are not in conflict — they are different quantities, and the marketing runs them together. The peptide is gone from plasma in minutes. The 20 to 24 hours is a claim about downstream effects, and it traces to the developers' review rather than to a controlled human duration-of-effect study.

There is no published human pharmacokinetic study of Selank by any route that we could find. No human C_max, no human half-life, no human AUC. Every number in circulation traces either to an unsourced line in a product leaflet or to the developing group's own rodent radiotracer work.

What the evidence shows

There is a real human literature here — around two hundred people in total. It is entirely Russian, almost entirely open-label, and it contains one result the marketing never mentions.

Registered trials on ClinicalTrials.gov: zero. No independent replication outside Russia by anyone.

The trial everyone cites: Selank versus a benzodiazepine

Zozulya, Neznamov and colleagues, 2008. Generalised anxiety disorder and neurasthenia, intranasal Selank 2,700 mcg a day in 22 patients against oral medazepam 30 mg a day in 10, over 14 days. High effectiveness was reported in 85% on Selank and 70% on medazepam, and where medazepam's anxiolysis came with sedation, Selank's came with a mild stimulating component.

That is a genuinely interesting result. Here is what is wrong with it:

• Not randomised, not blinded, no placebo arm. An open comparison.
• 22 against 10, with no stated allocation procedure.
• A five-day placebo run-in, with placebo responders excluded before the trial started. That removes the patients most likely to improve on anything. It inflates the apparent drug effect and means the numbers cannot be read as a response rate in ordinary patients.
• "85% versus 70%" is an unblinded global impression, not a scale-based effect size.
• The institute that developed the drug ran the trial and published the monograph we read it in.

The best-designed human study, and its result

Medvedev and colleagues, 2014, is the largest concurrent-comparator study that exists: 60 patients, 30 on intranasal Selank 2.7 mg a day against 30 on oral phenazepam 2 mg a day, over 14 days with a day-21 follow-up. Open and naturalistic by the authors' own description — again not blinded, not randomised.

The benzodiazepine won on acute efficacy, by more than double. That is not a finding you will see on a vendor page, and it is in the study those pages cite. What Selank did was hold its effect after treatment stopped, while phenazepam's collapsed, and cost far less in side effects along the way. That is a real and defensible profile — a weaker anxiolytic with a much cleaner tolerability picture — and it is a different claim from the one being sold.

Everything else

An open-label Phase II in 21 patients with no control group. A 20-patient observational study. A 15-patient pilot in older patients with vascular asthenia. A 70-patient study of Selank added to phenazepam. A single-dose resting-state fMRI study in 52 healthy volunteers. Every one is Russian, every one is intranasal, and only the two Medvedev studies have a concurrent comparator at all.

Reconstitution

A 10 mg vial, against doses in the hundreds of micrograms:

The 5 mL row makes a 500 mcg dose 25 marks on a U-100 syringe, which is the most forgiving of the three. Check your vial has the headroom for 5 mL first.

Reported protocols

The registered dose is measured in drops. The injectable dose is measured in micrograms and comes from nowhere we could find.

What the registered product says

Verbatim from the label: two drops in each nostril, three times a day, for 14 days, with the course repeatable after one to three weeks on a doctor's advice. The label gives no microgram figure at all.

At a nominal 0.05 mL drop of the 1.5 mg/mL solution — about 75 mcg a drop — that works out near 900 mcg a day. We could not verify the drop volume from any official source, so treat that conversion as an estimate rather than a label claim. Every microgram figure you see quoted for the registered dose is somebody's conversion, including ours.

The trial dose was higher than the licensed dose

Every clinical study used 2,700 mcg a day intranasally — the Phase II, the medazepam comparison, the vascular asthenia pilot and both Medvedev studies. That is roughly two to three times the label dose. The drug was licensed over the counter at a lower dose than the one it was trialled at, which is a checkable oddity worth knowing about.

The injectable convention

Storage

Lyophilised, sealed, cold, dark and dry. The conventions in our storage guide apply, and as always they are conventions carried across from peptides generally rather than stability data published for this compound.

Reconstituted in bacteriostatic water, the governing figure is the 28 days the benzyl alcohol preservative is validated for — and as the reconstitution section notes, at lower daily doses this vial outlasts that window. Our FAQs explain where the 28 days comes from.

Reported effects

The safety record is reassuring, and it is thin, and it is all from nose drops.

What the label reports

Adverse reactions, in full: allergic reactions including delayed ones, and an unpleasant taste if the drops run from the nasal cavity onto the pharynx. Contraindications are hypersensitivity, pregnancy and lactation, and anyone under 18, on the stated grounds of insufficient clinical data.

What the trials report

Pronounced drug-related adverse effects in 3 of 22 patients in the medazepam comparison. No adverse effects at all in the 21-patient Phase II. Mainly nasal dryness in the 30 Selank patients in Medvedev 2014, with tolerability significantly better than phenazepam — which is the clearest thing this compound has going for it.

"Anxiolytic without sedation or dependence"

Without sedation has real support: two open studies found benzodiazepine comparators produced sedation, asthenia, emotional indifference, sexual dysfunction and measurable cognitive impairment where Selank did not. Both were unblinded, and an unblinded rater judging sedation in a patient known to be on a benzodiazepine is precisely where expectation does the most work. Note also that the same study measured Selank's efficacy at less than half the benzodiazepine's.

Without dependence has never been tested in a human being. No withdrawal study, no discontinuation-emergent-symptom study, no abuse liability study, no long-term cohort. The one supporting observation — that the effect persisted seven days after stopping while the benzodiazepine's collapsed — is consistent with an absence of rebound, in 30 unblinded patients over one week. It is an inference from the absence of a benzodiazepine mechanism and the absence of reports. It is not a finding.

Regulatory status

Russia. Selank is registered as Селанк nasal drops 0.15%, 1.5 mg/mL in a 3 mL dropper bottle, to Peptogen, registration ЛП-№(010951)-(РГ-RU) dated 15 July 2025 — a re-registration of a product first registered in 2009. ATC N05BX, other anxiolytics. It has been available over the counter, without prescription, since 2 August 2017. Labelled indications run across anxiety, unmotivated worry, panic attacks, neurasthenia, asthenia, mood instability, sleep disturbance and adjustment disorders.

No injectable Selank product is registered in Russia. The state register carries nasal drops and bulk substance powder, and nothing else.

Ukraine. Registered as nasal drops 0.15%, registration UA/11687/01/01.

Anywhere else. Not approved in the United States, the EU, the UK, Canada, Australia or Japan.

United States

"Selank acetate (TP-7)" sits on FDA's bulk drug substances page in the table of substances nominated but withdrawn — entries previously in category 2 of the interim policies, withdrawn by the nominators. The entry reads, verbatim:

Note the phrase "for certain routes of administration." That is the agency pointing at injection, and it is the same language it used for Semax and for Epitalon.

Selank was not part of the July 2026 review. On 23 and 24 July 2026 FDA's Pharmacy Compounding Advisory Committee heard seven peptides under docket FDA-2025-N-6895 — BPC-157, KPV, TB-500, MOTS-c, DSIP, Semax and Epitalon. Selank was not among them, and FDA has published no briefing document on it. It is not on the 503A bulks list, not on the 503B nominated list, and not scheduled for the further consultation. That is a worse position than its sibling, not a better one: Semax at least got a hearing.

Canada

Selank is not named in Health Canada's public advisory of 9 April 2026 — nor is Semax. The advisory names fourteen peptides: BPC-157, CJC-1295, DSIP, Epitalon, GHK-Cu, HCG, Ipamorelin, KPV, Melanotan I and II, MOTS-C, NAD+, SS-31, TB-500 and Retatrutide.

Sport

Selank is not named on the 2026 WADA Prohibited List — we read the list and searched it. As with Semax, the S0 catch-all arguably does not reach it either: S0 covers substances with no current approval by any governmental regulatory health authority for human therapeutic use, and Russia's Ministry of Health is one. On the plain text, a current Russian marketing authorisation takes Selank outside S0.

That is a reading of list text, not a ruling. We found no WADA statement, no anti-doping organisation decision and no published case addressing it. National anti-doping organisations have taken varying views of Russian-approved-only compounds, and the practical exposure to an athlete is their organisation's judgement rather than a settled question. Anyone subject to testing should ask their own ADO rather than rely on this paragraph.

Sentient Biogenix supplies Selank for laboratory research use only. It is not for human or veterinary use.

Questions we actually get

Isn't Selank sold over the counter in Russia?

Yes, and that is true and verifiable — as nasal drops, since August 2017. It is a different dosage form from the one in this vial, and the over-the-counter status attaches to the drops, not to the molecule.

Has injected Selank ever been studied in people?

No. Every human study of Selank we could find is intranasal. Injected Selank exists in rats and mice and nowhere else. One frequently cited paper appears in English translation to describe injection in 52 healthy volunteers — the Russian original specifies 60 microlitres per nostril.

Is it really 92.8% bioavailable?

That figure is a line in a Russian product leaflet with no citation and no species named, and the method behind it almost certainly counted radioactive label rather than intact peptide. Ninety three per cent absolute bioavailability across nasal mucosa is not credible for an uncapped heptapeptide. Treat it as a tracer-recovery number, not a drug-exposure number.

Is it as good as a benzodiazepine?

On the best-designed study that exists, no. In a 60-patient open comparison, phenazepam reduced anxiety by 55% at day 14 against Selank's 26.3%. What Selank did better was hold its effect a week after stopping, and cost far less in sedation, cognitive impairment and sexual dysfunction. That is a real profile — a milder anxiolytic with much better tolerability — and it is not the profile being marketed.

Where does the injectable dose come from?

Nowhere we could trace. Not the registered product, not any trial, not any animal pharmacokinetic bridge. The two common protocols disagree with each other by an order of magnitude per dose, which tells you what you need to know about their derivation.

Is N-Acetyl Selank Amidate worth the premium?

There is no published study of it. None. Not in an animal, not in a person, not in a test tube. The two chemical databases people check for it are both publishing the wrong molecule — one of them is publishing Semax. Every claim about it is borrowed from plain Selank.

References

1. Peptogen. Селанк® (Selank) nasal drops 0.15% — registered product information (Russian), read via the RLS and Vidal drug registers. rlsnet.ru — registration number and date, dosage form, composition including the diacetate salt, indications, the drops-based dosing, the 92.8% bioavailability statement, and the adverse reactions and contraindications sections.
2. US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks — the nominated-but-withdrawn table, entry "selank acetate (TP-7)." fda.gov
3. US Food and Drug Administration. July 23–24, 2026 meeting of the Pharmacy Compounding Advisory Committee, docket FDA-2025-N-6895 — the seven peptides heard, Selank not among them. fda.gov
4. Zozulya AA, Neznamov GG, Syunyakov TS, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic. Zhurnal Nevrologii i Psikhiatrii im. S.S. Korsakova 2008;108(4). PMID 18454096. Design, doses and results read via the Zakusov Institute monograph «СЕЛАНК: original peptide anxiolytic» (Moscow, 2011) — a primary but interested source, as the institute developed the drug.
5. Medvedev VE, et al. Comparative efficacy of Selank and phenazepam in anxiety disorders. Zhurnal Nevrologii i Psikhiatrii im. S.S. Korsakova 2014;114(7):17–22. PMID 25176261. pubmed.ncbi.nlm.nih.gov — 60 patients, the 26.3% against 55% day-14 result, the day-21 responder counts and the adverse effect comparison.
6. Vyunova TV, Andreeva L, Shevchenko K, Myasoedov N. Peptide-based anxiolytics: the molecular aspects of heptapeptide Selank biological activity. Protein and Peptide Letters 2018;25(10):914–923. PMID 30255741. pubmed.ncbi.nlm.nih.gov — the GABA allosteric modulation finding, in isolated plasma membranes, and the blocking of diazepam's modulation.
7. Kost NV, Sokolov OY, Gabaeva MV, et al. Semax and Selank inhibit the enkephalin-degrading enzymes of human serum. Russian Journal of Bioorganic Chemistry 2001;27:156–159. PMID 11443939. link.springer.com — the 20 µM IC₅₀ the arithmetic in the mechanism section works from.
8. Kolik LG, Nadorova AV, Antipova TA, et al. Effect of Selank on BDNF content in rat brain structures under ethanol withdrawal. Bulletin of Experimental Biology and Medicine 2019;167:641–644. link.springer.com — 0.3 mg/kg/day intraperitoneally in rats, and the prevention of an ethanol-induced BDNF increase.
9. Volkova A, et al. Selank administration affects the expression of some genes involved in GABAergic neurotransmission. Frontiers in Pharmacology 2016;7:31. frontiersin.org — 30 male Wistar rats, single intranasal dose of 300 mcg/kg.
10. Kolomin T, Shadrina M, Slominsky P, Limborska S, Myasoedov N. A new generation of drugs: synthetic peptides based on natural regulatory peptides. Neuroscience & Medicine 2013;4:223–252 — the developing group's own review, source of the two-minute in-vitro half-life and the "acts continuously for 20–24 h" claim.
11. Panikratova YR, et al. Functional connectivity changes after single intranasal administration of Semax and Selank. Doklady Biological Sciences 2020;490:9–11. PMID 32342318. link.springer.com — 52 healthy volunteers. The English translation says "injection"; the Russian original specifies 60 microlitres per nostril.
12. Health Canada. Think twice before injecting peptides bought online: unauthorized products can seriously harm you. Public advisory, 9 April 2026. recalls-rappels.canada.ca
13. World Anti-Doping Agency. The 2026 Prohibited List, in force 1 January 2026, section S0. Read via the Austrian Federal Law Gazette's official reproduction (BGBl. III Nr. 219/2025) because WADA blocks automated access to its own copy.

What we could not read, and have therefore not described: the abstract of the 2008 medazepam trial itself, which is why its design is reported from the developing institute's monograph; the 2008 human immunomodulation paper, the only human immune study; and the mouse study comparing intranasal against intraperitoneal Selank, which is the single most decision-relevant animal paper for the question this page is about. We could not verify the drop volume behind any microgram conversion of the registered dose, the species behind the 92.8% figure, or any molecular weight for N-Acetyl Selank Amidate. Each of those is stated as a gap above rather than filled in.