Semax + Selank

Identity and composition

Semax + Selank is a co-formulation of two independent synthetic heptapeptides developed in Russia, studied in research for their neurotrophic (Semax) and anxiolytic/immunomodulatory (Selank) profiles. It is not a single molecule, but the combination of two distinct peptides in a single presentation.

Each component has its own chemical identity:

• Semax: sequence Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP); an analog of the ACTH(4-10) fragment, described as (Pro8,Gly9,Pro10)ACTH-(4-10). Identity references: CAS 80714-61-0, formula C37H51N9O10S, molecular weight 813.93 g/mol.
• Selank: sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro (TKPRPGP); analogue of the peptide tuftsin, also known as TP-7. Identity references: CAS 129954-34-3, formula C33H57N11O9, molecular weight 751.9 g/mol.

Since this is a combination of two separate molecules, there is no single CAS, molecular formula or molecular weight for the "Semax + Selank" combination: only the per-component values listed above apply. Both share a C-terminal Pro-Gly-Pro motif added to resist enzymatic degradation.

Product for research use.

Mechanism of action

These are two distinct mechanisms that operate through independent pathways, which constitutes the proposed rationale for combining them.

Semax is a synthetic analog of the ACTH(4-10) fragment with a Pro-Gly-Pro tail that resists enzymatic degradation. In preclinical models, its ability to increase the expression of BDNF (and of its receptor TrkB) and of NGF in the brain has been investigated. In an in vivo study, Semax was observed to increase BDNF expression in different regions of the rat brain (PMID 14556513). In a rat model of cerebral ischemia-reperfusion, a neuroprotective/anti-inflammatory profile was reported: an increase in active CREB and a decrease in MMP-9, c-Fos, and active JNK (PMID 34201112).

Selank is a synthetic analog of tuftsin, extended with Pro-Gly-Pro. Its best documented mechanism in the primary literature is the dose-dependent inhibition of enzymes that degrade enkephalins (more potent than bacitracin and puromycin in vitro), proposed as the basis of its anxiolytic activity (PMID 11550013), with additional immunomodulatory effects reported. Various secondary sources summarize Selank as a modulator of the GABA system; however, the primary evidence available here supports the inhibition of enkephalin-degrading enzymes, not a direct binding to GABA receptors.

Important: these mechanisms are described for each peptide separately; no studies were found on the specific co-formulation.

Pharmacokinetics

Both are peptides with low oral bioavailability, so in research they are administered by the parenteral or intranasal route (nasal spray, subcutaneous, or intravenous).

No reliable numerical value for half-life (t1/2) or Cmax was confirmed for either of the two peptides in the reviewed sources. Some secondary sources describe a rapid onset of action (within minutes) via the intranasal route, but no primary pharmacokinetic parameters were verified. Consequently, any specific half-life figure must be considered uncharacterized in this sheet.

Scientific evidence

The available evidence is preliminary and mostly preclinical (rodents), complemented by small Russian clinical studies on each peptide separately.

• Semax it has been studied mainly in contexts of cerebral ischemia/ischemic stroke and cognition; in rat models an increase in BDNF has been observed (PMID 14556513) and a neuroprotective profile in ischemia-reperfusion (PMID 34201112). - Selank it has been investigated as an anxiolytic peptide in anxiety models (PMID 24913576) and by its mechanism of inhibition of enkephalin-degrading enzymes (PMID 11550013); in Russian trials it has been reported comparably to benzodiazepines.

Key limits that must be made clear: no controlled studies were located on the specific Semax + Selank coformulation; the assessments of the combination are extrapolations from single-agent data. Neither of the two peptides has FDA or EMA approval, and Western replication is lacking.

Research applications

Product for research use.

This material is offered only for experimental in vitro work or in research models, handled by qualified personnel.

• It may be of interest for research in: studies of neurotrophic signaling (BDNF/NGF, TrkB pathway) associated with Semax; studies of anxiolytic mechanisms linked to the inhibition of enkephalin-degrading enzymes associated with Selank; comparative characterization of heptapeptides with the C-terminal motif Pro-Gly-Pro.
• Not applicable for: clinical use, therapeutic use, diagnosis, or prevention of any condition; nor for veterinary use. It is not an approved medicine and must not be used as such.

Since there are no studies on the specific combination, any experimental design that involves it must treat its combined effects as uncharacterized.

Research protocols

The reference presentation is 10 mg of Semax + 10 mg of Selank. This quantity describes the contents of the vial and is not linked to any clinical dosing evidence: it should not be interpreted as a usage guideline.

In the reviewed literature, no validated doses were identified for the Semax + Selank co-formulation, nor a trial phase for the combined product. The available studies correspond to each peptide separately and mostly to rodent models or small Russian trials, without transferable dose parameters that can be cited with direct support here.

For the foregoing reasons, experimental protocols must be defined by the researcher according to their design, without assuming equivalence with clinical dosing schemes.

Reconstitution

General standard laboratory guide for lyophilized peptides:

• It is usually reconstituted with bacteriostatic water (water for injection with ~0.9% benzyl alcohol), which helps to limit microbial growth in multi-dose uses. For some protocols sterile water for injection is also used.
• Add the diluent letting it run slowly down the wall of the vial, without injecting it directly onto the powder, to reduce mechanical stress on the peptide.
• Do not shake; swirl gently until fully dissolved. Let it stand until the solution becomes clear.
• The diluent volume is chosen according to the desired working concentration; since there are two peptides in the vial, consider that both are solubilized in the same volume.

Handle with aseptic technique at all times.

Stability and storage

Standard laboratory handling for this type of peptide:

• Lyophilized (powder): it is the most stable form. It is usually kept refrigerated and, for prolonged storage, frozen; protected from light and humidity. Under these conditions the dry material tolerates long-term storage well.
• Reconstituted (in solution): it is less stable. It is kept refrigerated (2-8 °C) and it is recommended to use it within a short time window. Avoid repeated freeze-thaw cycles, which can degrade the peptide.

These ranges are a general handling guide; no specific stability data were found for the co-formulation.

Safety profile

The safety profile should be read with caution and as preliminary. The Russian clinical reports on Selank describe the absence of the sedation, cognitive impairment, tolerance and dependence typical of benzodiazepines. Nevertheless, no rigorous long-term safety data or Western studies were found for either of the two peptides, and none for the combination.

Both remain research compounds not approved outside Russia/Ukraine, and the safety of the specific co-formulation is uncharacterized. No formal contraindications, interactions or quantified adverse-event data that could be cited are available in the consulted literature.

As research material, it must be handled with appropriate protective equipment and under the practices of a qualified laboratory. It is not intended for clinical use.

Comparative context

Within nootropic/anxiolytic peptides, each component contributes a distinct profile, and that complementarity is the rationale for combining them:

• Semax is distinguished by a dual upregulation of BDNF and NGF, uncommon among nootropics; it derives from the ACTH(4-10) fragment and its primary mechanism is neurotrophic.
• Selank differs from benzodiazepine-type anxiolytics by its reported lack of sedation and dependence; it is derived from tuftsin and its primary documented mechanism is the inhibition of enkephalin-degrading enzymes, with immunomodulatory effects.

Both share the C-terminal Pro-Gly-Pro motif, added to provide metabolic stability, but they come from different parent peptides and act by distinct pathways (neurotrophic versus enkephalinase inhibition/immunomodulation). There is, however, no direct comparative evidence on the blend as such.

History and development

Both peptides were developed and are used clinically in Russia.

• Semax appears on the Russian List of Vital and Essential Medicines, and has been studied mainly in cerebral ischemia/ischemic stroke and cognition.
• Selank was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences, and has been investigated for generalized anxiety disorder and neurasthenia, being reported in Russian trials as comparable to benzodiazepines (medazepam).

Neither of the two has FDA or EMA approval, and replication in the West is scarce. The combination "Semax + Selank" brings together two molecules with independent development histories; no studies on the co-formulation itself were identified.

FAQ

Customer reviews

Average rating: 5.0 out of 5, based on 7 customer ratings.

Certificate of analysis per batch

Semax + Selank batch with certificate of analysis published in the COA catalog:

• Batch EXO010626217E — 10 mg + 10 mg, issued 2026-05-30

Scientific references (2)

Peer-reviewed literature on Semax + Selank, with its PubMed identifier where available:

• Semax and its metabolites have an effect on the dopaminergic system (Dolotov OV, et al. · Neurochemical Research · 2005) — Study on the mechanism of action of Semax in the dopaminergic system. PMID 16362768.
• Semax and selank inhibit the enkephalin-degrading enzymes from human serum (Kost, et al. · Bioorganicheskaia Khimiia · 2001) PMID 11443939.

Otras presentaciones de Semax + Selank

• NA Semax Amidate
• Semax

Other related research peptides

• Adamax
• Cerebrolysin
• NA Selank Amidate
• NA Semax Amidate
• P21
• P21-Adamantane
• PE 22-28
• Selank
• Semax