Comparison
Semax vs Selank
Semax and Selank were both developed at the Institute of Molecular Genetics in Moscow and share the same stabilising Pro-Gly-Pro tail. They are often confused, but they are studied for opposite ends of the mental-state spectrum.
Semax vs Selank at a glance
| Semax | Selank | |
|---|---|---|
| Parent peptide | ACTH(4–7) | Tuftsin |
| Main research focus | Cognition, stroke recovery | Anxiety |
| Key mechanism | BDNF / TrkB upregulation | GABA and serotonin modulation |
| Russian registration | 0.1% and 1% nasal drops | 0.15% nasal drops |
| Typical description | Stimulating | Calming |
How they work
Semax
Rat studies show Semax rapidly increases brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the hippocampus — signals involved in learning, memory and neuronal survival. It also modulates dopamine and serotonin systems and affects expression of genes related to inflammation and blood vessels after experimental stroke.
Selank
Selank appears to modulate the GABA system — rat studies show it changes expression of GABA-receptor genes and enhances the effect of diazepam. It also influences serotonin metabolism, inhibits enzymes that break down enkephalins (the body's own opioid peptides) and affects immune cytokines, consistent with its tuftsin origin.
Side effects compared
Semax
Russian clinical use reports good tolerability. Reported effects include nasal irritation, headache and, rarely, anxiety or irritability. There are no large Western safety trials.
Selank
Russian clinical reports describe few side effects, mainly nasal irritation and occasional fatigue. No sedation or withdrawal syndrome was reported in those studies, but there are no large independent safety trials.
Bottom line
Semax is investigated as a cognitive and neuroprotective agent; Selank as an anxiolytic. Neither is licensed in the UK, and most clinical evidence for both comes from Russian studies.
Frequently asked questions
What is the main difference between Semax and Selank?
Parent peptide: Semax — ACTH(4–7); Selank — Tuftsin.
Is Semax or Selank licensed in the UK?
Semax is not licensed in the UK. Selank is not licensed in the UK and is not a controlled drug.