Semax et Selank : voies de recherche intranasale ou sous-cutanée
For most research peptides, the route is subcutaneous and there is nothing to discuss. Semax and Selank are the exception. The registered Russian products are nasal solutions, the published clinical work overwhelmingly uses that route, and the reason is not convenience — it is a specific problem in the pharmacology of getting peptides into the brain.
The problem the nasal route is trying to solve
Peptides are poor candidates for reaching the central nervous system. They are relatively large, they carry charge, and the blood–brain barrier is built precisely to exclude molecules like that. A peptide injected subcutaneously enters general circulation, is distributed around the body, is degraded by circulating enzymes, and only a small fraction ever reaches the brain.
For a compound whose entire research interest is peripheral — tissue repair, metabolic signalling — that does not matter. For a compound whose entire research interest is in the brain, it is the central obstacle.
What the nasal route does differently
The nasal cavity has an unusual feature: the olfactory epithelium at the roof of the cavity is one of the few places where the nervous system is separated from the outside world by very little tissue. The olfactory and trigeminal nerve pathways that pass through it are studied as a route by which molecules can reach the central nervous system while partly bypassing both general circulation and the blood–brain barrier.
This is a real and active field — the literature calls it nose-to-brain delivery, and it extends well beyond these two peptides. Two things follow from it:
- The peptide avoids first-pass metabolism. It does not have to survive a trip through the liver or a long residence in the bloodstream.
- Distribution is different, not just faster. The point is not that intranasal is a shortcut to the same outcome. It produces a different distribution profile, which is why the route is chosen in study design rather than just being a milder alternative to a needle.
The trade-off is that intranasal delivery is far less consistent. Nasal absorption varies with mucosal condition, the volume the cavity can hold, how much drains away, and how much is swallowed. Subcutaneous delivery is the more reproducible of the two, which is exactly why so much peptide research uses it.
Why this route is specific to certain compounds
Nose-to-brain delivery is not a general-purpose substitute for injection. The literature applies it to a narrow set of compounds, and there are structural reasons:
- Small peptides pass more readily. Semax is seven amino acids and Selank is similarly short. Larger peptides cross the nasal epithelium poorly.
- They must survive the environment. Both compounds carry the Pro-Gly-Pro stabilising tail that makes them resistant to rapid enzymatic breakdown — without which neither route would work.
- The target has to be central. The route only makes sense if the research question concerns the brain.
This is why you see nasal formulations of Semax and Selank and essentially never of BPC-157, tesamorelin or the metabolic peptides. It is not that nobody has tried; it is that the route does not suit the molecule or the question.
Saline rather than bacteriostatic water
One practical difference is worth understanding, because it catches people out.
Intranasal research formulations in the published literature are generally prepared in saline, not in eau bactériostatique. The reason is benzyl alcohol — the preservative that makes eau bactériostatique suitable for a vial that will be entered repeatedly. Benzyl alcohol is an irritant to nasal mucosa, and the nasal epithelium is considerably more sensitive than subcutaneous tissue.
The registered Russian nasal products are accordingly aqueous solutions formulated for that route, not reconstituted with a benzyl-alcohol-preserved diluent. Anyone reading the literature and assuming the diluent carries across from one route to the other has misread it.
This article describes what the published research literature has done and why. It is not a preparation protocol, and nothing here is guidance for administering any compound to a person. Vistara Labs does not supply administration instructions for any product.
Which route the literature actually uses
For Semax and Selank specifically, the honest summary is that the intranasal literature is the main literature. The Russian clinical work that gives these two compounds their unusual track record was done with nasal formulations. Subcutaneous work exists but is a smaller body of research, and it is not what the registrations rest on.
That inverts the usual situation in this category, where injection is the default and anything else is a curiosity. Here, the nasal route is the one with the clinical history behind it.
How the compounds are supplied
Semax and Selank are supplied as lyophilised powder in a sealed vial, the same as the rest of the research-peptide category. The freeze-dried form is used because the dry state is markedly more stable than any solution — it survives shipping, tolerates temperature variation, and stores far longer. The choice of diluent, and therefore the route a study uses, is made by the researcher after the vial arrives, not by the supplier.
Vistara Labs stocks Semax 10 mg and Selank 10 mg as lyophilised powder, and supplies Semax Nasal Spray and Selank Nasal Spray as metered atomisers for intranasal research preparations — supplied ready-mixed, from within Canada to every province, with a certificate of analysis available on request. Background on each compound: what the Semax research covers and what the Selank research covers.
Frequently asked questions
Why are Semax and Selank studied intranasally rather than by injection?
Because both are studied for effects in the brain, and peptides cross the blood–brain barrier poorly. The nasal route is investigated as a path to the central nervous system along the olfactory and trigeminal nerves, partly bypassing general circulation.
Is intranasal delivery just a needle-free alternative?
No. It produces a different distribution profile rather than the same outcome by an easier route, which is why it is chosen in study design. It is also less reproducible than subcutaneous delivery, since nasal absorption varies with mucosal condition and how much of an administered volume drains or is swallowed.
Why do nasal research formulations use saline instead of bacteriostatic water?
Because bacteriostatic water contains benzyl alcohol as a preservative, and benzyl alcohol is an irritant to nasal mucosa. The registered nasal products are formulated as aqueous solutions for that route instead.
Can any peptide be studied intranasally?
No. The route suits short, enzymatically stable peptides with a central nervous system target. Most research peptides meet none of those conditions, which is why nasal formulations of compounds such as BPC-157 or tesamorelin are not a feature of the literature.
How are Semax and Selank supplied?
The vial format is lyophilised powder in sealed vials, the standard across the research-peptide category. The nasal sprays are supplied ready-mixed in saline in sealed metered atomisers.
Where to buy Semax and Selank nasal sprays in Canada
Researchers looking to buy Semax nasal spray or buy Selank nasal spray in Canada can source both from domestic stock: Semax nasal spray (10 mg, pre-mixed) and Selank nasal spray (10 mg, pre-mixed) ship from within Canada, with e-transfer and credit card accepted. Both are supplied ready-mixed in saline, for laboratory research use only.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
