All products are for laboratory research purposes only. Not for human consumption.
Comparison
Semax vs Selank: What Each Is Studied For
They are almost always discussed together and they share an origin, a country of registration and a price. What they are studied for is not the same thing at all.
The short answer
Side by side
| Semax | Selank | |
|---|---|---|
| Classification | Synthetic heptapeptide, ACTH(4-10) analogue | Synthetic heptapeptide, tuftsin analogue |
| CAS number | 80714-61-0 | 129954-34-3 |
| Molecular formula | C37H51N9O10S | C33H57N11O9 |
| Molecular weight | 813.92 g/mol | 751.88 g/mol |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Strengths | 5 mg, 10 mg | 5 mg, 10 mg |
| From, per vial | $7.01 £5.54 | $7.01 £5.54 |
| From, per box of 10 | $70.14 £55.41 | $70.14 £55.41 |
| Research status | Registered as a medicine in Russia. Not approved in the UK, EU or US. Most published research is Russian-language and has not been widely replicated. | Registered as a medicine in Russia. Not approved in the UK, EU or US. Human data is limited and published largely in Russian-language journals. |
In detail
What the research actually compares
Descriptions of published research activity and findings. Nothing here is a claim about what these products do, or a statement that either is safe or effective for any purpose.
Different parent molecules
Semax is built from ACTH(4-10), a fragment of adrenocorticotropic hormone, with a Pro-Gly-Pro tail added to slow enzymatic breakdown. Selank is built from tuftsin, a four-residue fragment of an immunoglobulin, with the same Pro-Gly-Pro stabilising strategy. The shared tail is why the two look related on paper; the parent fragments they come from are unrelated.
What each is actually studied for
The Semax literature centres on neurotrophins: published work reports that it regulates BDNF and its receptor trkB in the rat hippocampus, and that it activates transcription of neurotrophin genes after cerebral ischaemia. The Selank literature centres on anxiety: a Russian clinical study reported anxiolytic effects the authors described as comparable to benzodiazepines, and animal work has examined it in morphine withdrawal.
The evidence problem they share
Almost all of the human data for both compounds was produced in Russia and published in Russian-language journals, and very little has been independently replicated elsewhere. That is not evidence that the findings are wrong, but it is a materially weaker base than a compound with multi-country trials behind it. Treat the clinical claims for both with the same caution.
Practical differences
None worth speaking of. Both are supplied as lyophilised powder in boxes of ten vials, both at 5 mg and 10 mg, and both at identical prices. The choice between them is about which research question you are asking, not about cost or format.
Common questions
Which is better, Semax or Selank?
Neither, because they are studied for different things. No published study has compared them head to head. Semax research concentrates on neurotrophin expression and neuroprotection models; Selank research concentrates on anxiolytic activity. The useful question is which of those a given experiment is designed to probe.
Are Semax and Selank approved anywhere?
Both are registered as medicines in Russia. Neither is approved in the UK, the EU, the US or any other major jurisdiction, and both are supplied here strictly as reference material for laboratory research.
Why do they both end in Pro-Gly-Pro?
It is the same stabilising strategy applied to two different parent fragments. Short peptides are broken down quickly by peptidases; adding a Pro-Gly-Pro tail slows that considerably. The shared tail is a formulation choice by the same research group, not evidence that the two molecules do related things.
