Description
Selank and Semax are both synthetic peptides developed in Russia, and they’re often mentioned together because they share a similar research lineage and are used for related purposes, though they act somewhat differently.
Selank
- A synthetic analog of the endogenous peptide tuftsin (an immunomodulatory peptide).
- Studied mainly for anxiolytic (anti-anxiety) effects, along with some claimed nootropic and immune-modulating properties.
- Proposed mechanism involves influencing GABA and serotonin systems, as well as regulating enkephalin degradation (via effects on enkephalinase enzymes).
- Typically administered intranasally in the contexts where it’s studied/used, since peptides are broken down if taken orally.
Semax
- A synthetic analog of a fragment of ACTH (adrenocorticotropic hormone), though it lacks hormonal activity.
- Studied mainly for cognitive-enhancing (nootropic) and neuroprotective effects — things like memory, focus, and recovery after stroke or brain injury.
- Proposed mechanism involves boosting BDNF (brain-derived neurotrophic factor) and NGF (nerve growth factor), and modulating dopamine/serotonin activity.
- Also typically given intranasally.
Key comparison
| Selank | Semax | |
|---|---|---|
| Origin | Tuftsin analog | ACTH(4-10) fragment analog |
| Primary reported effect | Anxiolytic, stress-reduction | Nootropic, neuroprotective |
| Secondary effects | Mild cognitive/immune effects | Mild anxiolytic effects |
| Main proposed pathway | GABA/serotonin, enkephalinase inhibition | BDNF/NGF upregulation |
A practical way people frame the difference: Selank is generally positioned as the one aimed more at calming/anxiety, while Semax is positioned more toward mental sharpness and neuroprotection — though there’s overlap, and both are used off-label/research-context rather than as approved medications in most countries (Semax and Selank do have limited approved medical use in Russia).
Worth noting: research on both is limited mostly to Russian studies and smaller trials, so the evidence base is thinner than for well-established drugs, and they aren’t approved by the FDA or EMA.
