Semax vs Selank: Research Profile Comparison
Semax and Selank are routinely mentioned in the same breath, and for once there is a real reason: both are synthetic heptapeptides developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, both are registered as medicines in Russia and in almost no other jurisdiction, and both are studied largely through Russian-language literature that is unevenly translated. That shared provenance is where the similarity ends. They derive from entirely different parent molecules and are studied against different pathways.
| Semax | Selank | |
|---|---|---|
| Parent molecule | SemaxFragment of adrenocorticotropic hormone — the ACTH(4–10) sequence, modified at the C-terminus for stability | SelankAnalogue of tuftsin, a tetrapeptide fragment of immunoglobulin G, extended with a stabilising tripeptide |
| Length | SemaxHeptapeptide (7 residues) | SelankHeptapeptide (7 residues) |
| Primary research focus | SemaxNeurotrophic and neuroprotective models; attention and memory paradigms in rodent studies | SelankAnxiolytic models; immunomodulation via the tuftsin pathway |
| Proposed mechanism | SemaxReported to increase BDNF and NGF expression in preclinical models; no corticotropic activity, the ACTH hormonal action having been engineered out | SelankReported to modulate GABAergic and monoamine signalling, and to inhibit enkephalin degradation, in preclinical models |
| Regulatory status | SemaxRegistered as a medicine in Russia; no MHRA, EMA or FDA authorisation — see our Semax legal note | SelankRegistered as a medicine in Russia; no MHRA, EMA or FDA authorisation — see our Selank legal note |
| Evidence base | SemaxSubstantial Russian clinical literature, limited independent Western replication | SelankSmaller literature than Semax, similarly concentrated in Russian-language publications |
| Handling | SemaxLyophilised; short-chain peptide handling applies — see storage | SelankLyophilised; short-chain peptide handling applies — see storage |
Takeaway
The shared institute, shared peptide length and shared regulatory position make these two look like a matched pair, and they are genuinely studied alongside one another. But Semax descends from a pituitary hormone fragment and is studied for neurotrophic signalling, while Selank descends from an immunoglobulin fragment and is studied for anxiolytic and immunomodulatory activity. The single most important caveat applies to both equally: the evidence base is overwhelmingly Russian-language and thinly replicated outside it, so confidence intervals on any reported finding should be read as wider than the publication count alone suggests.
Research-profile comparison for laboratory reference only — not a usage, dosing, or stacking guide. See our legal & compliance hub for the regulatory position on either compound.
Common Questions
Are Semax and Selank the same compound?
No. Both are seven-residue synthetic peptides from the same research institute, which is why they are so often paired, but they come from different parent molecules — Semax from an ACTH fragment, Selank from the immunoglobulin-derived tetrapeptide tuftsin — and are studied against different pathways.
Does Semax still act like ACTH?
The ACTH(4–10) fragment Semax is based on lacks the portion of the hormone responsible for corticotropic activity, and the published rationale for the molecule is specifically that the hormonal action is absent while neurotropic activity is retained. It is studied as a neuroactive peptide, not as a hormone analogue.
Is Semax legal in the UK?
Semax has no UK marketing authorisation and is not a licensed medicine here; it is supplied for laboratory research use only. Our Semax legal note sets out the position, and the UK compliance overview covers the framework it sits in.
Why is most Semax and Selank research in Russian?
Both were developed at the Institute of Molecular Genetics of the Russian Academy of Sciences and brought to market within the Russian pharmaceutical system, so the clinical literature accumulated there. Independent replication in Western journals is limited, which is a meaningful limitation on how confidently any individual finding should be read.
Are Semax or Selank on the WADA Prohibited List?
Neither appears on the Prohibited List as a named substance at the time of writing, but WADA revises the list annually and also prohibits broad classes of compound by mechanism rather than only by name. Anyone subject to anti-doping testing should check the current list with WADA directly rather than rely on a supplier page.