Two peptides, one Russian research lineage
Semax and Selank both come from the Russian Academy of Sciences research network that has spent decades developing short peptides as nasal drops. Both are seven amino acids long, both end in the same Pro-Gly-Pro sequence added to slow their breakdown, and both are sold in Russia by the manufacturer Peptogen as non-prescription nasal drops. That shared ancestry is why the two names get mentioned in the same breath, and why people searching for one often want to know how it differs from the other.
Past the shared tail, they are built on different starting molecules and were developed for different things.
Where the two peptides diverge
Semax is built on ACTH 4-7, a fragment of adrenocorticotropic hormone, the pituitary hormone that normally drives cortisol release. Semax keeps only the piece of ACTH that appears to act in the brain and drops the part that acts on the adrenal glands. It was developed for stroke recovery and cognition, and its best-documented mechanism is a rise in brain-derived neurotrophic factor (BDNF), shown in rats after a single intranasal dose.
Selank is built on tuftsin, a small fragment of the antibody protein immunoglobulin G with roles in immune signalling. It was developed for anxiety and stress, and the proposed mechanisms come from rat gene-expression work pointing to the GABA system, plus older work suggesting it protects the body's own calming opioid peptides (enkephalins) from breakdown.
| Semax Stocked locally | Selank Stocked locally | |
|---|---|---|
| Built on | ACTH fragment (4-7) | Tuftsin (immune peptide) |
| Developed for | Stroke recovery, cognition | Anxiety, stress |
| Best-documented mechanism | BDNF and trkB, shown in rats | GABA gene expression, shown in rats |
| Human comparator trials | vs standard rehabilitation (stroke) | vs medazepam and phenazepam (benzodiazepines) |
| Russian product strengths | 0.1% and 1% nasal drops | 0.15% nasal drops |
| Non-prescription in Russia since | Sold as 0.1%/1% drops | August 2017 |
What the human evidence actually shows
Neither peptide has a large, independently replicated, placebo-controlled trial published in an English-language journal. That single fact matters more than any mechanism story.
For Semax, the main human study is a 2018 Russian trial that randomised 110 adults recovering from ischaemic stroke to Semax plus standard rehabilitation, or rehabilitation alone, over five months. Blood BDNF rose faster on Semax and daily-living scores improved faster in the first month. It was not placebo-controlled, and it measured BDNF in blood rather than in the brain.
For Selank, two Russian trials compared it against a benzodiazepine rather than a sugar pill. A 2008 trial put it head to head with medazepam in 62 people with generalised anxiety disorder or neurasthenia and found a similar anti-anxiety effect, with Selank reported to add a mild anti-fatigue effect the benzodiazepine lacked. A 2014 trial compared it with phenazepam in 60 people with anxiety and somatoform disorders and reported a comparable effect with a mild nootropic angle. Both trials were small, both came from the same research network that developed the peptide, and neither used a placebo arm.
Read individually, each study looks encouraging. Read as a body of evidence, both peptides sit at the same stage: promising rat mechanism work, plus small human trials against an active comparator rather than placebo, mostly published in Russian-language journals, with no confirmation from an outside research group.
Side effects: an honest gap
Russian clinical papers for both peptides describe them as well tolerated, but the published abstracts do not give side-effect counts, so no reliable frequency figure exists for either one. Nasal irritation is a plausible issue with any nasal drop, simply because that is true of nasal drops generally, not because either peptide has a documented rate. Long-term data in healthy adults does not exist for either compound. Cerebrolysin, the other peptide product associated with stroke recovery, has a larger published trial base than either.
Choosing between them is choosing a use case, not a winner
Semax and Selank were not designed to compete with each other. Semax's published work centres on stroke rehabilitation and a BDNF mechanism; Selank's centres on anxiety and a GABA mechanism. Someone searching for a "smarter" or "calmer" option between the two is really asking which use case matches their interest, not which peptide has stronger data, because by the site's own evidence standard, neither has the kind of trial base that settles the question either way.
Status in the Philippines
Neither Semax nor Selank is registered with FDA Philippines as a medicine, and neither is a scheduled controlled substance under RA 9165. Both reach the Philippines exclusively through research-chemical suppliers, usually as lyophilised powder rather than the finished Russian nasal drops. Anyone considering either compound is working from a smaller and less independently verified evidence base than for an approved medicine, and that gap does not close just because two peptides share a research lineage.
Both peptides are popular in Manila's office and biohacker circles for the same reason: they promise a nasal-drop or injectable alternative to registered stimulants, anxiolytics or nootropic drugs, without the prescription step. That popularity is a market fact, not a clinical one. Neither compound has been evaluated for stroke care or anxiety treatment by any Philippine regulator, and both sit outside the country's pharmacy system entirely.
Storage
Lyophilised powder for either peptide is best kept refrigerated and away from light before mixing. Once reconstituted, both should be kept at 2 to 8°C in the main body of the fridge rather than the door, and a brownout can push a household fridge out of that range within a few hours in Manila's climate. The beginner guide covers handling basics that apply to both peptides equally.
