Semax vs. Selank: shared origins, different targets

These two are often discussed together because they come from the same place and share a design trick. Their research focus is quite different, though.

Shared background

• Both were developed in Russia at the Institute of Molecular Genetics of the Russian Academy of Sciences. Both are registered as medicines in Russia, but neither is approved by the FDA or EMA.
• Both are short synthetic peptides with a C-terminal Pro-Gly-Pro extension added to a natural parent sequence. The extension is intended to slow enzymatic breakdown.
• Much of the literature is Russian-language and comes from a fairly small number of groups. Large Western RCTs are lacking for both.

Semax

• Its parent is ACTH(4–7), a fragment of adrenocorticotropic hormone with no meaningful hormonal (adrenal) activity.
• Research has focused on neuroprotection and cognition, including use after stroke in Russian clinical practice. Studies report effects on BDNF expression and on dopaminergic and serotonergic systems.

Selank

• Its parent is tuftsin, an immunomodulatory tetrapeptide.
• Research has focused on anxiety. Proposed mechanisms include modulation of GABAergic signaling and inhibition of enkephalin-degrading enzymes, plus some immunomodulatory effects.

Bottom line

Semax research leans cognitive and neuroprotective, and Selank research leans anxiolytic. For both, mechanism claims are ahead of robust human outcome data.

If you’ve found good papers on either one, especially independent replications, please share them below.