Selank

Selank is a synthetic peptide derived from the naturally occurring human tetrapeptide tuftsin. It consists of seven amino acids and was developed by combining tuftsin with a stabilizing sequence to increase its duration of action in the body.

Selank is purported to help regulate anxiety, improve mood, and enhance cognitive function. Studies suggest it may influence the balance of neurotransmitters such as serotonin and dopamine, which play roles in stress response and emotional stability.

The peptide Selank has been studied for its anxiolytic properties. In clinical-context and cellular studies it has demonstrated reductions in anxiety comparable to low doses of benzodiazepines. For example, in cell cultures it appears to modulate the system of GABAergic system by altering GABAₐ receptor-related binding and thereby influencing gene expression linked to anxiety responses. Studies in animals also found that single injection of Selank mitigated anxiety induced by ethanol withdrawal in rats, supporting its anxiolytic potential ^{1, 2}.

Selank has also shown cognitive and immunomodulatory effects in pre-clinical and human studies. Animal work indicates improved learning and memory consolidation under stress or hypoxia alongside elevations in neurotrophic factors such as Brain-Derived Neurotrophic Factor (BDNF). Studies also show modulation of immune-system gene expression, with changes in inflammatory cytokine profiles and immune cell signalling in both rodents and human cohorts ³. Taken together, these results suggest that Selank’s main benefits include anxiety reduction, cognitive enhancement, and immune system support.

Although the word on Selank’s safety is positive, dedicated safety studies — English-language ones, at least — are absent, and the few details we have are mentioned in passing. For example, in a 2013 review on synthetic peptides that spans nearly 30 pages, we get only these statements on Selank’s side effect profile ⁴.

• “Selank has a prolonged effect and no side effects and, on the whole, is [efficiently delivered] in young and elderly monkeys.”
• “The action of Selank is not accompanied by undesirable characteristics (hypnosedation and myorelaxation) and side effects (amnesia, withdrawal, and dependence).”
• “According to the results of preclinical and clinical studies of Semax and Selank, it can be concluded that both peptides are safe and highly effective.”

That makes Selank look pretty good from a safety perspective, but the U.S. Food & Drug Administration (FDA) would disagree with the claim that the peptide is free of side effects. Specifically, the FDA warns that compounded drugs containing Selank pose a risk for immunogenicity, a state in which the body perceives a substance as a threat and mounts a potentially life-threatening immune response against it. The FDA qualifies the risk to “certain routes of administration” but doesn’t specify which routes, and also notes a lack of safety information concerning Selank administered to humans ^{5, 6}.

Selank is a synthetic heptapeptide which appears to exert its action in the central nervous system by modulating the inhibitory neurotransmitter GABA-A receptor complex; for example, in a rodent study it acted as a positive allosteric modulator of GABA binding, suggesting it enhances GABAergic inhibition ⁷. Additionally, studies in neural tissue show that Selank alters the expression of genes involved in neurotransmission and the GABAergic system, though it does not directly change the mRNA levels of GABAergic genes in human neuroblastoma cells, implying an indirect modulatory effect. Moreover, clinical research in patients with generalized anxiety disorder found changes in enkephalin activity accompanying Selank treatment, indicating it may also influence endogenous opioid-peptide systems alongside GABAergic modulation ^{8, 9}.

The U.S. Food and Drug Administration has flagged selank acetate as a peptide for which the agency “lacks important information” and has identified safety/compounding concerns (the agency listed selank acetate among peptide bulk drug substances that pose immunogenicity/quality risks) ¹⁰. While, not specifically prohibited in sports, athletes should never assume a substance is permitted just because it is not explicitly named on a list. They must check with the relevant anti-doping authority for their sport or league.