Selank and Phenibut: Poorly Studied GABAergic Peptide Drugs Sold as Supplements in the US | Research

The takeaway

Selank and phenibut are Russian-developed GABAergic compounds sold as unregulated dietary supplements in the US despite limited safety data, with phenibut poison control calls rising substantially over 5 years.

Rising poison control calls
Phenibut-related calls to US poison control centers have increased substantially over 5 years, highlighting risks of unregulated GABAergic supplement sales

What the researchers found

Selank and phenibut are poorly studied GABAergic drugs sold as US dietary supplements. Phenibut poison control calls have increased substantially, and both carry risks of dependence, withdrawal, and serious adverse effects when misused.

Why it matters

People are buying selank and phenibut without prescriptions, often unaware of their risks. This review highlights the regulatory gap that allows poorly studied GABAergic peptides and drugs to be sold as supplements.

The numbers in context

Phenibut poison control calls rising over 5 years; high-dose GABA drugs cause respiratory depression, coma, death; chronic use causes dependence and withdrawal

How the study worked

Narrative review of pharmacology, clinical effects, abuse potential, and safety profiles of selected GABAergic agents including flunitrazepam, GHB, phenibut, and selank.

Who was studied

Review of pharmacology and abuse data for flunitrazepam, GHB, phenibut, and selank

What this study cannot tell us

Narrative review, not systematic. Very limited clinical data on selank specifically — most information comes from Russian literature that may not meet international standards. The review groups selank with much more dangerous substances, which may overstate its individual risk profile.

How to read the evidence

Not applicable (narrative review). Highlights the lack of rigorous clinical evidence for selank and phenibut safety and efficacy.

When this study was published

Published in 2021. Regulatory attention to GABAergic supplements has continued to increase since publication.

The bigger picture

The sale of unregulated GABAergic compounds as supplements raises serious safety concerns. As peptide-based supplements gain popularity, this review underscores the need for proper pharmacological evaluation before public access — particularly for substances with sedative and addictive potential.

Questions still open

Should selank be regulated differently from phenibut given that it is a peptide with a different safety profile?
What would rigorous clinical trials reveal about selank's actual efficacy and safety for anxiety?
Could selank offer benefits over benzodiazepines if properly studied, or does its GABAergic activity carry similar risks?

Common questions

Is selank safe to take as a supplement?

There is insufficient clinical evidence to confirm selank's safety. It is a synthetic peptide with GABAergic activity sold as a supplement in the US, but it has not undergone the rigorous testing required for FDA-approved medications. Caution is warranted.

What is the difference between selank and phenibut?

Selank is a synthetic peptide derived from the immune protein tuftsin with anxiolytic properties. Phenibut is a modified GABA molecule with stronger sedative effects. Both affect GABA receptors, but phenibut has a more established pattern of abuse, dependence, and withdrawal.

Read the original research

Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.

Journal of clinical pharmacology, 61 Suppl 2, S114-S128

View on PubMed ↗Publisher’s paper ↗

Citation

Doyno, Cassandra R; White, C Michael. (2021). Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.. Journal of clinical pharmacology, 61 Suppl 2, S114-S128. https://doi.org/10.1002/jcph.1922