Selank vs Semax — two Russian-developed peptides, two different origins
Semax is a synthetic analogue of a fragment of adrenocorticotropic hormone (ACTH 4-10). Selank is a synthetic analogue of tuftsin, an immunomodulatory tetrapeptide. They share a development origin in Russian research institutes and are often sold together, but they descend from unrelated parent molecules and were investigated in different research areas.
Selank and Semax are almost always sold as a pair, which creates the impression they are two versions of one idea. They are not related. What they share is a development lineage — both came out of Russian research institutes — and a literature that is unusually hard to evaluate from English-language sources.
Different parent molecules
| Semax | Selank | |
|---|---|---|
| Derived from | A fragment of adrenocorticotropic hormone (ACTH 4-10) | Tuftsin, an immunomodulatory tetrapeptide |
| Modification | Analogue of the fragment, stabilised against rapid degradation | Analogue of tuftsin, similarly stabilised |
| Primary research area | Neurological and cognitive models | Anxiolytic and immunomodulatory models |
| Published footprint | The larger of the two, including Russian clinical work | Smaller, more heavily preclinical |
Why the evidence is hard to read
A large share of the primary literature on both compounds was published in Russian-language journals, some of which are not indexed in the databases most readers search. The practical consequence is that claims circulate widely while the underlying papers are rarely read — and when a claim is repeated often enough without anyone checking the source, it acquires a confidence the evidence does not support.
- Check whether a cited study is accessible at all, not merely that a citation exists.
- Check whether the finding has been replicated outside the originating institution.
- Distinguish preclinical models from clinical work — the two are routinely conflated for these compounds.
- Treat translated abstracts carefully: an abstract is not a methods section.
What is verifiable
The mechanism literature is contested. The contents of the vial need not be. Both compounds are short sequences that are straightforward to characterise analytically, so a certificate naming the analysing laboratory with an attached chromatogram settles identity and purity regardless of where the pharmacology debate lands.
The compounds discussed here
Frequently asked questions
- Are Selank and Semax related compounds?
- Only by development history. Semax derives from a fragment of ACTH; Selank derives from tuftsin, an immunomodulatory tetrapeptide. Both were developed in Russian research institutes, which is why they are usually catalogued together, but structurally they are unrelated.
- Why is there less English-language research on these?
- Much of the primary literature was published in Russian-language journals, and a substantial portion is not indexed in the databases most readers search. That makes the evidence base harder to evaluate, not necessarily thinner — but it does mean claims are frequently repeated without anyone having read the source.
- Is one better studied than the other?
- Semax generally has the wider published footprint, including clinical work conducted in Russia. Selank's literature is smaller. In both cases, independent replication outside the originating research environment is limited, which is the relevant caveat when weighing any reported finding.
References
Primary literature for the compounds above. Links open the record on PubMed.
- The efficacy of semax in the treatment of patients at different stages of ischemic stroke Gusev EI, et al. Zh Nevrol Psikhiatr Im S S Korsakova. 2018. PMID 29798983 → · summary
- Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia Medvedev VE, et al. Zh Nevrol Psikhiatr Im S S Korsakova. 2007. PMID 18454096 → · summary
- Neuroprotective and antiamnesic effects of Semax during experimental ischemic infarction of the cerebral cortex Stavchansky VV, et al. Bull Exp Biol Med. 2007. PMID 17603664 → · summary