Side-by-side evidence
Outcomes where both peptides have published data. Each cell carries two grades: clinical evidence (human-RCT depth for this specific outcome) and community evidence (real-world adoption). How we grade evidence.
| Outcome | Selank | Semax |
|---|---|---|
| Anxiolytic effect | Clinical:Preliminary Community:Strong Russian trials report anxiolytic effects comparable to benzodiazepines without sedation. | Clinical:Preliminary Community:Moderate Mild anxiolytic effect; primary action is stimulation, not calming. |
| Cognitive / focus enhancement | Clinical:Preliminary Community:Strong Some reported attention and learning effects; data sparse outside Russian-language sources. | Clinical:Preliminary Community:Moderate Stimulant-style focus and BDNF elevation reported in rodent and small clinical studies. |
| Side effect burden | Clinical:Preliminary Community:Strong Generally well tolerated in available trials; nasal irritation possible. | Clinical:Preliminary Community:Moderate Generally well tolerated; can cause overstimulation or insomnia at higher doses. |
The Two Leading Nootropic Peptides
Selank and Semax are both synthetic peptides developed at the Institute of Molecular Genetics in Russia. Both are approved medications in Russia and have decades of clinical use — making them among the most well-studied nootropic peptides in existence.
Despite their shared origin, they target different neurological pathways and produce distinct cognitive and emotional effects.
Mechanism of Action
Selank (Anxiolytic + Cognitive)
Selank is a synthetic analog of the immunomodulatory peptide tuftsin, with added stability. Its primary mechanisms:
- GABAergic modulation — enhances GABA signaling, the brain's primary inhibitory system
- Serotonin metabolism — influences serotonin and its metabolites in the brain
- BDNF expression — increases brain-derived neurotrophic factor
- Enkephalin stabilization — slows the breakdown of endogenous anxiety-reducing peptides
- IL-6 modulation — anti-inflammatory effects in the CNS
Selank's profile is anxiolytic-first — it reduces anxiety while simultaneously supporting cognitive function.
Semax (Cognitive + Neuroprotective)
Semax is a synthetic fragment of ACTH (adrenocorticotropic hormone, residues 4–10) with a modified C-terminus for stability. Its mechanisms:
- BDNF and NGF upregulation — strongly increases neurotrophic factors
- Dopaminergic modulation — enhances dopamine and serotonin turnover
- Cholinergic enhancement — supports acetylcholine signaling (memory & learning)
- Neuroprotection — protects neurons from oxidative stress and ischemic damage
- Cortical excitability — increases attention and information processing
Semax's profile is cognition-first — it enhances focus, memory, and processing speed with secondary mood benefits.
Quick Comparison Table
| Feature | Selank | Semax |
|---|---|---|
| Primary effect | Anxiety reduction + cognition | Cognitive enhancement + neuroprotection |
| Core pathway | GABAergic / serotonergic | BDNF / dopaminergic / cholinergic |
| Anxiety reduction | Strong (primary effect) | Mild (secondary) |
| Focus / attention | Moderate | Strong (primary effect) |
| Memory | Moderate improvement | Strong improvement |
| Neuroprotection | Mild | Strong |
| Stimulating? | No — calming | Mildly — some users report alertness |
| Administration | Intranasal | Intranasal |
| Typical dose | 250–500 mcg/day | 200–600 mcg/day |
| Onset | 10–15 minutes | 10–15 minutes |
| Duration | 3–6 hours | 4–8 hours |
| Russian approval | Yes (anxiolytic) | Yes (nootropic/neuroprotective) |
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