> Research Use Only (RUO): Selank is a synthetic research peptide not approved by the FDA for human use in the United States. All dosage figures, protocols, and study citations on this page are drawn from published preclinical and investigational research — including Russian clinical trials where Selank holds regulatory approval. This content is intended solely for qualified researchers. Nothing here constitutes medical advice, diagnosis, or treatment recommendations.
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What Is Selank? A Quick Pharmacological Overview
Selank (sequence: Thr-Lys-Pro-Arg-Pro-Gly-Pro; abbreviated TKPRPGP) is a synthetic heptapeptide developed in the 1990s at the Institute of Molecular Genetics of the Russian Academy of Sciences — the same institution that produced Semax. It is a structural analog of tuftsin, an endogenous tetrapeptide derived by enzymatic cleavage of immunoglobulin G that is naturally produced in the spleen and known for its immunostimulatory and mild nootropic properties.
The critical structural innovation in Selank is the Pro-Gly-Pro C-terminal extension grafted onto the tuftsin backbone. This tripeptide tail shields the molecule from rapid degradation by serum aminopeptidases and prolongs plasma half-life to approximately 15–20 minutes after intranasal delivery — a dramatic improvement over the minutes-long half-life of native tuftsin.
Primary Mechanisms
Selank does not operate through a single receptor like a classical drug. Its pharmacological profile emerges from simultaneous activity across several systems:
GABAergic modulation. Clinical studies published in Frontiers in Pharmacology (Semenova et al., 2017; PMID 28293190) demonstrated that Selank alters the gene expression of 84 proteins involved in GABAergic neurotransmission in human neuroblastoma cells. Unlike benzodiazepines — which directly open GABA-A receptor chloride channels — Selank modulates GABAergic tone through gene-expression changes, producing calm without forcing receptor occupancy or generating dependence signatures.
BDNF upregulation. Selank reliably increases brain-derived neurotrophic factor (BDNF) mRNA and protein in hippocampal and prefrontal cortical regions. A 2019 study (PMID 31625062) confirmed that Selank protected against ethanol-induced memory deficits specifically through BDNF regulation in these circuits — the same regions implicated in working memory and executive function.
Enkephalin system. Selank inhibits enzymes responsible for degrading endogenous enkephalins, elevating the availability of these endogenous opioid-adjacent peptides. This likely contributes to the mood-brightening and anti-fatigue effects reported in the comparative clinical trial.
Monoaminergic effects. Secondary modulation of serotonin and dopamine neurotransmission has been characterized in animal models, contributing to the mild psychostimulant and motivational profile observed in the clinical literature.
This multi-target mechanism is why Selank occupies a unique niche in research: it combines anxiolytic, nootropic, and immunomodulatory endpoints in a single molecule, with a pharmacological footprint distinctly different from either benzodiazepines or classic BDNF-raising compounds.
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Why Intranasal Administration Is the Primary Route
Of all the administration routes studied for Selank, intranasal delivery is the most well-characterized in the clinical literature, and it is the route associated with the compound's regulatory approval in Russia and Ukraine.
The pharmacokinetic rationale is straightforward. When delivered as nasal drops or a metered-dose nasal spray, Selank crosses the olfactory and trigeminal mucosal epithelium and reaches cerebrospinal fluid measurably within minutes — effectively bypassing the blood-brain barrier. Rodent studies estimate bioavailability via the intranasal route at approximately 92.8%, which is strikingly high for a peptide.
Subcutaneous injection is also used in research contexts and shares the same dosage range, but the foundational comparative clinical trial (Zozulia & Neznamov, 2008) used intranasal dosing exclusively. Researchers designing studies to match or replicate that evidence base therefore default to intranasal.
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Reconstitution Protocol
Selank arrives as a lyophilized white powder in a sealed glass vial with a rubber septum. Before use in any research context, it must be reconstituted with an appropriate aqueous vehicle.
Materials Required
- •Selank lyophilized vial (typical vial sizes: 5 mg or 10 mg)
- •Bacteriostatic water (BAC water) — 0.9% benzyl alcohol; the benzyl alcohol provides antimicrobial preservation and extends the usable life of the reconstituted solution
- •Two alcohol swabs
- •A sterile syringe with needle for transfer
- •A metered-dose nasal spray bottle (0.10 mL/spray actuation) for intranasal use
- •An insulin syringe for subcutaneous use
> Note: Sterile saline (0.9% sodium chloride) may be substituted for BAC water, but it provides no preservative function. Solutions made with saline must be used more quickly and are not appropriate for multi-day protocols without fresh preparation.
Step-by-Step Reconstitution
1. Wipe both vials — use separate alcohol swabs on the rubber septum of the Selank vial and the BAC water vial. Allow each to air-dry for 30 seconds.
2. Draw bacteriostatic water — using a sterile syringe, draw the appropriate volume of BAC water (see concentration table below).
3. Inject slowly into the Selank vial — direct the stream against the glass wall, not directly onto the powder. This prevents mechanical damage to the peptide structure.
4. Do not shake — gently swirl or rotate the vial until the powder fully dissolves. Shaking generates foaming that can denature the peptide.
5. Transfer to spray bottle (intranasal use) — draw the reconstituted solution into the syringe and fill the nasal spray bottle. Pump the sprayer several times to prime and confirm actuation volume.
Concentration Reference Table
| Vial Size | BAC Water Added | Concentration | Volume per 0.10 mL Spray |
|---|---|---|---|
| 5 mg | 2.0 mL | 2,500 mcg/mL | 250 mcg |
| 5 mg | 5.0 mL | 1,000 mcg/mL | 100 mcg |
| 10 mg | 5.0 mL | 2,000 mcg/mL | 200 mcg |
| 10 mg | 10.0 mL | 1,000 mcg/mL | 100 mcg |
Most common research preparation: 5 mg vial + 2.0 mL BAC water → 2,500 mcg/mL → 250 mcg per 0.10 mL spray actuation. This matches the standard single-dose lower bound from the clinical literature and makes dose accounting straightforward.
For subcutaneous research: reconstitute the 5 mg vial in 2.0 mL BAC water and draw 0.10 mL (10 units on a standard insulin syringe) per 250 mcg dose.
> Use the Peptides.SO Peptide Reconstitution Calculator to verify volumes for any vial size and target concentration before preparation.
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Dosage Ranges from the Research Literature
Selank's dosing parameters are better established than most research peptides, owing to the Russian regulatory clinical trials. The following ranges are drawn from published clinical and preclinical research.
Intranasal Dosage Ranges
| Research Context | Dose per Administration | Frequency | Total Daily |
|---|---|---|---|
| Anxiolytic — low end | 250 mcg | 2–3× daily | 500–750 mcg |
| Anxiolytic — standard clinical | 400–750 mcg | 2–3× daily | 800–1,500 mcg |
| Anxiolytic — high clinical | 750–1,000 mcg | 2–3× daily | up to ~2,700 mcg |
| Immunomodulation (influenza prophylaxis) | 300 mcg | 3× daily for 5–7 days | 900 mcg |
| Cognitive/attention under stress | 250 mcg (morning + early PM) | 2× daily | 500 mcg |
> Doses above 1,000 mcg per administration are not associated with proportionally greater anxiolytic effect in the literature and are not characteristic of the registered protocol.
Subcutaneous Dosage Ranges
Subcutaneous injection shares the same per-dose range (250–1,000 mcg) but is less well-characterized in the clinical literature. All head-to-head comparisons to medazepam used intranasal delivery.
Starting Parameters for Research
The foundational 62-patient Zozulia & Neznamov (2008) trial used approximately 300–400 mcg per intranasal dose, three times daily, for 14 days, matching the Russian registered nasal drops formulation (~75 mcg/drop; 4 drops per nostril). This is the most directly evidence-anchored parameter set available.
250 mcg (one spray per nostril at 2,500 mcg/mL concentration) represents the practical minimum for most research designs and functions as a full working dose — Selank does not require titration or a loading phase.
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Timing Protocols
Daily Timing
Selank's intranasal half-life of approximately 15–20 minutes produces relatively rapid onset and short duration of peak CNS exposure, though downstream effects on BDNF and enkephalin metabolism persist beyond the pharmacokinetic window. The clinical literature supports a morning and afternoon split for two-dose protocols, keeping the later dose before early evening to avoid any interference with sleep architecture.
Two-dose protocol (500 mcg/day):
- •Dose 1: Morning, upon waking
- •Dose 2: Early afternoon (12:00–14:00)
Three-dose protocol (750–1,200 mcg/day, matching registered Russian protocol):
- •Dose 1: Morning
- •Dose 2: Midday
- •Dose 3: Early evening (before 18:00)
Cyclical Protocol
The registered clinical protocol and the Zozulia & Neznamov (2008) trial both used 14-day treatment courses. After a completed course, research designs typically incorporate a 14-day washout before a second cycle. This approach reflects both the observed sustained effects beyond the treatment window and the absence of dependence signals that would otherwise require prolonged tapering.
Selank does not produce receptor downregulation or tolerance signatures consistent with benzodiazepine-class compounds, which is one reason the 14-on/14-off pattern rather than indefinite dosing is the standard research design.
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Selank + Semax: Research Stacking Context
Semax and Selank are structurally unrelated peptides from the same Russian research program that act through complementary mechanisms: Semax is primarily a melanocortin analog with strong BDNF-upregulating and pro-cognitive properties, while Selank leads with GABAergic modulation and anxiolytic endpoints. Both share the intranasal route and overlapping BDNF modulation, which is why they are frequently co-studied.
In research contexts where investigators are interested in simultaneous anxiolytic and cognitive-enhancement endpoints, Semax and Selank are sometimes co-administered, each at the lower end of their respective dose ranges (250 mcg Semax / 250 mcg Selank, both intranasal, morning dose). The theoretical rationale is that Semax's stimulating-nootropic profile may be moderated by Selank's GABAergic calming tone, and Semax may amplify the BDNF component of Selank's mechanism.
No published controlled clinical trial has tested this combination directly. Research using it should be considered exploratory and outside the established clinical evidence base.
For a detailed comparison of both peptides' mechanisms and research profiles, see the Semax vs Selank Neuroprotective Peptides Comparison Guide.
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Storage and Stability
Proper storage is essential to preserve Selank's bioactivity across a research protocol.
Lyophilized (Powder) — Unopened Vial
- •Long-term: Store at or below −18°C (−0.4°F), desiccated (with silica gel or in a sealed container to exclude moisture)
- •Short-term (up to 3 weeks): Room temperature is acceptable if desiccated and away from light, but refrigerator storage is preferred over relying on room-temperature stability
- •Lyophilized Selank is generally stable for up to 24 months at −18°C or below when properly sealed
Reconstituted Solution
- •Refrigerator (2–8°C): Stable for 2–7 days when reconstituted with bacteriostatic water; solutions made with plain sterile saline should be used within 24–48 hours
- •Freezer (−18°C or below): Store aliquots for up to 3 months; allow to thaw slowly at room temperature before use
- •Freeze-thaw cycles: Minimize — each cycle degrades the peptide. For protocols longer than one week, pre-aliquot into single-week volumes before freezing
| Form | Refrigerator (2–8°C) | Freezer (−18°C) |
|---|---|---|
| Lyophilized | Up to 3 weeks (not ideal) | Up to 24 months |
| Reconstituted in BAC water | 2–7 days | Up to 3 months |
Light and oxygen also degrade peptides. Store reconstituted Selank in opaque or amber-colored vials when possible, and purge with inert gas or minimize headspace if storing for more than a few days.
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Safety Profile from Research
Selank's safety profile, as characterized in published Russian clinical research, is notably clean relative to classical anxiolytics.
No sedation. In the Zozulia & Neznamov (2008) trial, Selank produced anxiolytic effects equivalent to medazepam on the Hamilton Anxiety Scale (HAM-A), Zung Self-Rating Anxiety Scale, and Clinical Global Impression (CGI) instrument — but without the sedation or cognitive dulling that accompanied the benzodiazepine comparator. Researchers documented a mild stimulant and anti-fatigue effect in the Selank group that was absent in the medazepam group.
No receptor downregulation. Unlike benzodiazepines, which produce GABA-A receptor downregulation with chronic use, Selank does not appear to reduce receptor density or sensitivity in available animal studies. No withdrawal phenomena have been characterized.
Low adverse event burden. Published Russian clinical data report minimal adverse events at registered doses. The most common finding is mild nasal mucosal irritation associated with intranasal delivery, which is technique- and formulation-dependent rather than compound-specific.
No dependence liability. The absence of direct GABA-A agonism and the demonstrated lack of tolerance in animal models suggest low dependence liability, distinguishing Selank from the benzodiazepine class it functionally competes with at the anxiolytic endpoint.
> These findings derive from the Russian clinical literature. No independent Phase II/III Western RCTs have been conducted. Researchers should treat the Russian evidence base as preliminary and interpret safety data accordingly.
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Evidence Summary & Key Citations
| Source | Finding |
|---|---|
| Zozulia et al., 2008 (Zh Nevrol Psikhiatr) | 62-patient RCT: Selank = medazepam for HAM-A, Zung; added antiasthenic + mild stimulant effect |
| Semenova et al., 2017 (PMID 28293190; Front Pharmacol) | GABAergic gene expression modulation in IMR-32 neuroblastoma cells |
| Malkova et al., 2019 (PMID 31625062) | Selank protects against ethanol-induced memory deficits via BDNF regulation |
| Institute of Molecular Genetics RAS, various | Tuftsin backbone, Pro-Gly-Pro stability extension, 92.8% intranasal bioavailability |
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Where Researchers Source Selank
Selank is available from numerous peptide research suppliers. The Peptides.SO platform lists 145+ verified suppliers offering Selank in both lyophilized powder and pre-mixed nasal spray formats.
When evaluating suppliers, research protocols typically prioritize:
- •Third-party COAs (Certificate of Analysis) verifying peptide purity ≥98%
- •HPLC mass spectrometry confirmation of molecular weight (MW: 751.86 g/mol)
- •Sterility testing especially for injectable-grade products
- •Proper lyophilized packaging for stability in transit
- •Cold-chain shipping for pre-mixed solutions
Selank is available in 5 mg vials (most common), 10 mg vials, and occasional 2 mg vials. Nasal spray kits (pre-mixed at 0.15–0.5 mg/mL) are also available from select suppliers.
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Internal Research Context
This dosage protocol guide is designed to complement two existing resources on this platform:
- •Selank Research Profile: Tuftsin Analog, Anxiolytic & Immunomodulatory Mechanisms — foundational profile covering the biology, receptor pharmacology, and full mechanism overview
- •Semax vs Selank Neuroprotective Comparison Guide — head-to-head mechanistic and dosing comparison for researchers studying both compounds
- •Nootropic Peptides Compared: Semax, Selank, Dihexa & P21 — broader comparative hub for the neuroprotective peptide class
Use the Peptide Reconstitution Calculator to generate precise volume calculations for your specific vial size and target dose before preparation.
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For research use only. Not for human use. Not FDA-approved. Selank holds regulatory approval in Russia and Ukraine as a prescription anxiolytic; no equivalent approval exists in the United States or European Union. All protocols and dosage parameters described on this page are drawn exclusively from published preclinical and clinical research literature and are intended for use by qualified investigators in appropriate research settings.