Selank Trials: A Tuftsin Analogue Tested Against Benzodiazepines

LynxLab · 24 October 2026 · 8 min read

How Selank was built from tuftsin, what the Russian generalised anxiety trials against medazepam and phenazepam measured, and why it is unlicensed in the UK.

Photo: Miles Burke, Unsplash

Selank is a seven-amino-acid peptide designed in Moscow as a stabilised copy of tuftsin, a fragment of the body's own antibodies. In Russia it is registered as an anxiolytic. The claim that follows it around the internet, that it works like a benzodiazepine without the side effects, comes from three small Russian trials published between 2008 and 2015. This post explains how selank was built, what those trials measured, and what they can and cannot support.

From tuftsin to Selank: the design

Tuftsin is a four-amino-acid fragment, Thr-Lys-Pro-Arg, cut from the heavy chain of human immunoglobulin G. It was described in the 1970s by Victor Najjar at Tufts University, which gave it its name, as a stimulator of phagocytes. It is a natural product of the immune system, not a neuropeptide.

The Institute of Molecular Genetics of the Russian Academy of Sciences, working with the Zakusov Research Institute of Pharmacology, took that four-residue sequence and added Pro-Gly-Pro to the end. The authors of a 2016 paper in Frontiers in Pharmacology explain that the tail was added "to improve its metabolic stability and yield a relatively longer duration" (Volkova et al., Frontiers in Pharmacology, 2016). The result is Thr-Lys-Pro-Arg-Pro-Gly-Pro.

The compound has the formula C33H57N11O9 and a molecular weight of about 752 (PubChem CID 11765600). In the pharmaceutical literature it is also called TP-7, and the Russian product is a diacetate salt. The selank peptide sold for research carries the same seven-residue sequence.

How a Russian anxiolytic came out of an immune peptide

The jump from phagocyte stimulant to anti-anxiety drug was not planned. Animal work from the Moscow group found that the tuftsin analogue relieved "aggression and fear reaction in different animal species", and early clinical studies led by Sergei Seredenin at the Zakusov Institute, published in 1990 and 1998, followed. The 2016 Frontiers paper summarises those studies as showing an effect "similar to that of tranquilizers at low doses" without "amnesia, withdrawal, and dependence".

Russia registered the compound as a medicine. A 2022 review in the journal Pharmaceutics lists Selank thirteenth in a table of 14 original Russian peptide drugs, with its clinical group given as "anxiolytic" (Deigin et al., Pharmaceutics, 2022).

The 2008 generalised anxiety trial against medazepam

The best-known Selank trial was published in 2008 by Alexander Zozulya and colleagues at the Mental Health Research Centre in Moscow, with Nikolai Myasoedov and Sergei Seredenin as senior authors. It enrolled 62 patients with generalised anxiety disorder or neurasthenia. Thirty received Selank and 32 received medazepam, a benzodiazepine (Zozulya et al., Zhurnal Nevrologii i Psikhiatrii, 2008).

Patients were scored on the Hamilton anxiety scale, the Zung scale and the Clinical Global Impression scale. The abstract reports that "the anxiolytic effects of both drugs were similar", and that Selank also had "antiasthenic and psychostimulant effects" that medazepam did not.

The same study measured enkephalins in blood. Patients with GAD and neurasthenia had a shortened half-life of leucine-enkephalin, which correlated with how long they had been ill and how severe their anxiety and fatigue were. During Selank treatment that half-life increased, mostly in the GAD patients. The sibling post on this site explains how Selank is thought to work, including this enkephalin finding.

The phenazepam comparisons, 2014 and 2015

Phenazepam is a potent benzodiazepine widely prescribed in Russia and not licensed in the UK. In 2014 Vladimir Medvedev and colleagues compared Selank with phenazepam in 60 patients with anxiety-phobic and somatoform disorders, coded F40.2-9, F41.1-9 and F45.0-1 under ICD-10 (Medvedev et al., Zhurnal Nevrologii i Psikhiatrii, 2014). The abstract reports "pronounced anxiolytic and mild nootropic effects" of Selank, and says the anxiolytic effect "lasted for a week after last receiving the peptide".

A follow-up in 2015 asked a different question: what happens when Selank is added to phenazepam? Thirty patients received phenazepam alone and 40 received phenazepam plus Selank. The combination reached its effect on the Hamilton depression scale earlier, and reduced the side effects of phenazepam, listed as "attention and memory impairment, asthenia, sedation, increase in sleep duration, sexual disturbances, emotional indifference and orthostatism", both during treatment and after the tranquilliser was withdrawn (Medvedev et al., Zhurnal Nevrologii i Psikhiatrii, 2015).

What "comparable to benzodiazepines" does and does not mean

The phrase is accurate as a summary of the 2008 abstract. Selank matched medazepam on anxiety scales in a 62-patient study. It is also the full extent of the claim, and five features of the evidence limit it.

No placebo arm: the comparator in each trial was an active benzodiazepine, so the trials cannot show how much of either drug's effect was placebo.
No blinding reported: the abstracts do not describe double-blind design, and a nasal peptide is hard to blind against a tablet.
Small samples: 30 to 40 patients per arm is a pilot-trial size by UK standards.
One research network: the designers of the peptide at the Institute of Molecular Genetics are co-authors on all three trials.
Russian-language publication: all three appear in the Korsakov Journal of Neurology and Psychiatry, with English abstracts only.

None of these makes the trials wrong. They mean that the trials are hypothesis-generating by the standards NICE would apply to a new anxiolytic. A UK clinician who wanted to compare Selank with diazepam would have to start with a randomised, placebo-controlled trial, because none exists. Laboratories that buy selank for behavioural work are, in effect, working upstream of that trial.

Legal status in the UK, EU and US

In Russia Selank is a prescription medicine. Everywhere else it is a research chemical. The MHRA's guidance on unlicensed medicines states that they "do not have a marketing authorisation in the UK and may not have been assessed by the MHRA" (MHRA, Supply unlicensed medicinal products, updated 2025). Selank has never held a UK authorisation and is not a controlled substance, which is why it can be sold for laboratory use but not for human use.

The FDA has gone further. In its review of bulk substances nominated for pharmacy compounding, it placed "Selank acetate (TP-7)" in category 2, the list of substances that "may present significant safety risks". Its reasoning was that compounded Selank "may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation and peptide-related impurities" and that the agency "lacks important information regarding any safety issues raised by selank acetate administered to humans" (FDA, Certain Bulk Drug Substances, category 2).

There is no EU authorisation through the EMA either. For anyone searching for selank uk suppliers, the practical position is that the vial comes with a lab report, not a patient leaflet, and the research-use-only label is a legal fact rather than a slogan.

LynxLab stocks selank 10mg for research use at £24.99 a vial, tested to 99% purity, with the certificate of analysis on the product page.

What a sceptical reader should take from the trials

The Selank story is coherent. A stable immune-derived peptide, screened for behaviour in animals, moved into Russian psychiatry and matched two benzodiazepines on anxiety scales in three small trials, with fewer sedative side effects. The 2015 finding that it reduced phenazepam's side effects while the tranquilliser was being withdrawn is the most clinically interesting result in the set.

The story is also thin at every point a regulator would press on. No placebo, no blinding, fewer than 200 patients in total, and a single research network across 15 years of papers. For laboratories sourcing selank for research, that is the state of the human evidence in October 2026: suggestive, consistent, and untested outside Russia.

Frequently asked questions

Is Selank a benzodiazepine?

No. Selank is a peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, derived from the immune fragment tuftsin. It was compared with the benzodiazepines medazepam and phenazepam in Russian trials in 2008, 2014 and 2015, and matched them on anxiety scales, but it is a different class of molecule with no confirmed receptor.

Is Selank approved in the UK?

No. Selank has no marketing authorisation from the MHRA, the EMA or the FDA. It is registered as an anxiolytic in Russia only, and the FDA has placed it in category 2 of its compounding list because it lacks safety information for human use.

What did the Selank anxiety trials find?

Zozulya and colleagues reported in 2008 that Selank and medazepam had similar anxiolytic effects in 62 patients with generalised anxiety disorder or neurasthenia. Medvedev and colleagues reported in 2014 and 2015 that Selank had a pronounced anxiolytic effect in 60 patients and reduced the side effects of phenazepam in a 70-patient study.

Why is Selank called a tuftsin analogue?

Tuftsin is the natural four-residue fragment Thr-Lys-Pro-Arg from the heavy chain of immunoglobulin G. Selank is that sequence with Pro-Gly-Pro added at the end to slow its breakdown by peptidases, so it is an analogue in the chemical sense: the same core with a stabilising extension.

Sources

Research use only

Selank from LynxLab

10mg vials from £24.99. ≥99% purity, lab report on the page. Same-day dispatch, UK stock.

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