BlendsSemax + SelankSelank/Semax blend

Semax / Selank Blend

Fixed-ratio nootropic blend · Semax 10 mg + Selank 10 mg · intranasal

This is the pre-mixed pairing of the two Russian nootropic peptides that are almost always run together — Semax, the activating ACTH-fragment analog, and Selank, the non-sedating tuftsin analog people use to take the edge off. It is the best-fitting blend in this library on practical grounds and one of the weakest on mechanistic grounds, and both halves of that are worth saying. Practically, nothing has to be reconciled: same manufacturer, same nasal route, same 14-day course, same molecular design — an active natural fragment with a Pro-Gly-Pro cap bolted on so it survives long enough to work. The 1:1 ratio is settled, and because the two components' registered dose ranges overlap, every sensible draw lands both halves inside their own page's bands. Mechanistically, though, the pairing has no shared cell, no shared receptor and no shared measurable output — the complementarity is at the level of how it feels, not how it works, and no published study has ever tested the two together. This page is about the plain peptides, not the N-acetyl amidate variants sold under nearly the same name.

TL;DRThe whole page · in 30 seconds

Drive plus calm · Nasal spray · 14-day course · The Russian pair

The two Russian nootropics almost nobody runs separately. Semax brings the drive and focus, Selank takes the edge off without sedating — and because they were designed by the same institute on the same template, they want the same nasal route, the same schedule and the same 14-day course. One bottle covers both.

The basics

A pre-mixed powder, almost always 10 mg Semax + 10 mg Selank, mixed into a nasal spray bottle.
Both are short peptides built the same way — an active natural fragment with a Pro-Gly-Pro tail added so it survives long enough to reach the brain.

Why people use it

Drive and calm from one bottle — the pairing people reach for is activation without the edge, which is exactly what running these two together is meant to produce.
Nothing has to be reconciled — same route, same schedule, same course length, same manufacturer. Unlike most blends here, there is no cadence or dose clash to work around.
The ratio actually fits — at 1:1 every sensible daily dose lands both halves inside their own page's bands, which no other blend in this library manages.
Nose-to-brain is the point — about nine times more Semax reaches the brain intranasally than intravenously, which is why the registered products are nasal drops rather than injections.

How to run it

Dose: 1,500 mcg of blend a day (750 mcg of each) at the standard build — 1,000 to start
How often: Three administrations, one spray per nostril each
How: Nasal spray — the route every human study of either peptide used
When: First half of the day; Semax is activating and can disturb sleep
Cycle: 14 days on, then a break — both registered courses are 14 days

Stacks well with

A choline source — Alpha-GPC or CDP-choline feeds the acetylcholine the focus effect runs on.
Separate bottles, if you want to move one without the other — a fixed 1:1 can only go up or down as a pair.

Good to know

Check what you actually bought: the plain peptides and the N-acetyl amidate versions are sold under nearly identical names, and several vendors print the plain peptides' chemistry while advertising the modified ones.
No study has ever tested the two together. Every one that mentions both ran them as separate arms.
A home-mixed nasal bottle is not preserved the way the registered product is — build small and use it inside two weeks.
Research vials ship as acetate salts, so a "10 mg" vial is about 9.3 mg of actual peptide. The 1:1 ratio survives that; the absolute numbers run about 7% optimistic.
Neither is on the WADA list by name, but neither is approved outside Russia either — see the FAQ before assuming anything for tested sport.

Bottom line: The one blend here where the packaging decision is genuinely the right one — as long as you hold the mechanism claim loosely, because two peptides that pair well in practice have never been shown to pair well in a study.

Molecular identity

Specs

Composition: Semax 10 mg · Selank 10 mg = 20 mg per vial. 5 mg + 5 mg is the other common size; 30 mg + 30 mg is sold for the amidate variantsCross-source vendor agreement
Ratio: 1 : 1 by mass — 50 % Semax · 50 % Selank. Settled convention, unlike most blends: 17 of 19 vendors publishing a split use itCross-source vendor agreement
Structure / class: Fixed-ratio, co-lyophilized blend of two Pro-Gly-Pro-capped regulatory peptide analogs — not a new molecule; each component keeps its own identity and pharmacologyCross-source vendor agreement
Semax (10 mg): C37H51N9O10S · 813.9 g/mol · CAS 80714-61-0 · UNII I5FAL2585H · Met-Glu-His-Phe-Pro-Gly-ProPubChem CID 9811102
Selank (10 mg): C33H57N11O9 · 751.9 g/mol · CAS 129954-34-3 · UNII TS9JR8EP1G · Thr-Lys-Pro-Arg-Pro-Gly-ProPubChem CID 11765600
Salt form: Research vials ship as acetate salts. Semax acetate is 874.0 g/mol and Selank acetate 811.9, so a nominal 10 mg is ≈9.31 mg and ≈9.26 mg of free peptide — about 7 % less than the label. The 1:1 ratio is unaffectedPubChem CID 155977617 / 155489759
Molecular target: No shared target — Semax acts through neurotrophic (BDNF/TrkB) signaling, Selank by inhibiting enkephalin-degrading enzymes. Neither has a confirmed receptorPMID 16996037 · PMID 11443939
Regulatory status: Both registered in Russia by the same manufacturer — Semax is prescription-only and on the Vital & Essential Medicines list, Selank is over-the-counter and is not. Neither has an INN or USAN, neither is FDA- or EMA-approved, and neither has ever been registered on ClinicalTrials.govRussian state register (ГРЛС) · FDA · ClinicalTrials.gov

Plain English

Mechanism

A blend is a packaging decision, not a new drug: the vial holds two peptides freeze-dried together in fixed proportions, so every draw carries both in the vial's ratio. What makes this pairing coherent is not a shared target — it is a shared design. Both peptides are built to the same template by the same research program: take a short active fragment of a natural regulatory molecule, then bolt a C-terminal Pro-Gly-Pro onto it so that peptidases do not destroy it before it can act. Semax takes ACTH(4-7), the Met-Glu-His-Phe run from adrenocorticotropic hormone; Selank takes tuftsin, the Thr-Lys-Pro-Arg fragment of the antibody molecule. That common stabilizing strategy is why the two behave so similarly in a nasal formulation, want the same route, and are registered with the same course length by the same manufacturer.

What they do once inside is entirely separate. Semax's best-supported action is neurotrophic: in rodent brain a single dose raises BDNF protein and its exon-III mRNA and drives TrkB phosphorylation, and it binds brain tissue specifically at a dissociation constant near 2.4 nM. Selank's best-supported action is the one shown in human serum rather than rodent brain — it slows the enzymes that degrade the body's own enkephalins, raising enkephalin levels. Beyond that its documented effects are rodent: hippocampal BDNF mRNA, GABA-related gene expression in frontal cortex, altered brainstem serotonin metabolism. Several studies have put the two side by side — the enkephalinase work, a comparison of their anticoagulant effects, a rat parkinsonism model, a stem-cell toxicity screen — but in every one of them the peptides were run as separate arms or compared against each other. None co-administered them.

This is where the pairing has to be held honestly, because it is weaker than the argument behind the CJC-1295 / Ipamorelin blend and it is weaker in a specific way. That blend works because two named receptors sit on one identified cell — the pituitary somatotroph — and produce one measurable output, a growth-hormone pulse, reproducing a two-signal system the body already runs. You can name the cell and measure the endpoint. Semax and Selank share none of that. Neurotrophic signaling and enkephalinase inhibition do not converge on any identified structure, neither peptide has a confirmed receptor, and neither has a validated human biomarker to measure. The complementarity here — drive plus calm — is phenomenological. It describes how the pair is reported to feel, not a mechanism by which they combine.

And nothing has tested them together. A thorough search returns no co-administration study in any model at any ratio. Every published paper mentioning both ran them as separate arms or compared them: the 52-participant resting-state fMRI study gave Semax, or Selank, or placebo; the rat parkinsonism study tested each alone and found only Selank affected anxiety-like behavior, with neither affecting motor activity; the stem-cell work tested each separately. The synergy argument is an inference from two unrelated mechanisms plus a great deal of user report. It is a reasonable thing to try. It is not a finding.

Sources:DOI 10.4236/nm.2013.44035 PMID 16996037 PMID 16635254 PMID 11443939 PMID 26924987 PMID 18841804 PMID 32342318 PMID 30225715 PMID 28702721

Why people reach for it

Potential benefits

This pairing is reached for by people who want Semax's activation without Semax's edge, on a schedule that takes no effort to keep. Here is what the research reports and what draws people to it.

The complementarity is the whole point — Semax is described as sharpening focus and drive; Selank as taking the edge off without sedating. Running them together is meant to give the first without the jitteriness, which is why almost nobody who uses one long-term uses it alone. Note that this is a report about subjective effect, not a demonstrated interaction.
Genuinely no scheduling compromise — Same nasal route, same daily schedule, same 14-day registered course, same manufacturer. Where the repair blends have a cadence clash and the growth-hormone blends have a dose clash, this pair has neither — the only timing constraint is Semax's, and Selank has none that conflicts with it.
A ratio that actually fits — At 1:1 every daily dose from 900 to 2,400 mcg of blend lands both components inside their own page's bands — note those bands run above the registered adaptation range at the top end, where the figures come from research doses rather than the label. No other blend in this library manages that, and it is only possible because the two components' dose ranges overlap in the first place.
Nose-to-brain delivery with a real number behind it — About 0.093% of an intranasal Semax dose is reported in brain within two minutes, against roughly 0.01% given intravenously — a nine-fold difference, and the stated reason the intranasal route was chosen for human use. Selank's registered label claims 92.8% absolute bioavailability across the nasal mucosa.
Selank's best-supported human result is not the one people quote — It is not "as good as a benzodiazepine". In a 70-patient study Selank given alongside phenazepam reduced that benzodiazepine's own side effects — attention and memory impairment, sedation, asthenia — both during treatment and through withdrawal. That is a more interesting and better-supported claim than the one usually made for it.
An honest limit — No study has tested the combination, neither peptide has a confirmed receptor, and the entire clinical literature for both is Russian, small, and produced by the network that developed them. Nothing here has been independently replicated by a Western trial.

Sources:DOI 10.4236/nm.2013.44035 PMID 1652713 PMID 26356395 DOI 10.1002/(SICI)1520-6769(199609)19:2<115::AID-NRC171>3.0.CO;2-B PMID 31667971

What the research reports for each component separately, and what people reach for the pairing for — not proven outcomes for the combination, which has never been studied. The clinical evidence for both components is Russian, small, and developer-run.

Implied timing

Best time to dose

Implied best time

First half of the day

Run the whole day's administrations before mid-afternoon. This is the one place the two halves do not start from the same instruction, and the resolution is that Semax's constraint wins because Selank does not have one that conflicts.

Semax's registered label is explicit for the adaptation and mental-fatigue indication: two to three drops per nostril, two to three times, in the first half of the day. It is an activating compound, and its own page's most common reason to cycle is the same reason not to dose it late — it can disturb sleep.
Selank's registered regimen is three times a day with no time-of-day restriction, because it is non-sedating and is described as anti-asthenic rather than calming in the sedative sense. Compressing its three administrations into the first half of the day therefore costs nothing.
So the blend runs on Semax's clock. That is a real scheduling constraint — it is the one thing about this pairing that does have to be reconciled — but it resolves cleanly in one direction, which is not true of the cadence clash on Wolverine or the dose clash on Tesa/Ipa.
Both peptides clear fast — Semax's parent molecule survives only minutes, with Pro-Gly-Pro as the longer-lived metabolite — while the reported effect of a single Semax dose is described as persisting 20 to 24 hours. As with the growth-hormone blends, the value is in what the dose triggers, not in sustained blood levels.

Reasoned from the two registered labels and from each component page's own conclusion. No study has established an ideal time of day for either compound, and none has studied the pair.

Sources:DOI 10.4236/nm.2013.44035 PMID 16523722

How to run it

Dosing & protocol

The unusual thing about dosing this blend is that there is almost nothing to trade off. Because the ratio is 1:1 and the two components' registered ranges overlap, picking a daily dose sets both halves at once and both land where they should. The real constraint is not the ratio — it is the nose, which takes only about 0.1 mL per nostril before the rest runs straight back out. That caps one administration at roughly two sprays, so the way you increase the dose is by adding administrations, not by making one bigger. The tiers below are therefore stated per day.

Community convention and registered labels, not trial-proven for the pair: no study has tested Semax with Selank. Neither is FDA- or EMA-approved and neither has ever been on ClinicalTrials.gov. These figures assume a 10 mg + 10 mg vial mixed into 10 mL — a different vial or bottle changes every number here.

Tiered daily ranges (total blend per day)

Standard build: a 20 mg vial into a 10 mL bottle = 2,000 mcg/mL of blend, which is 1,000 mcg/mL of each — the registered Semax 0.1% strength exactly. At the 0.125 mL pump that is 250 mcg of blend per spray, so 125 mcg of each. One administration is one spray per nostril: 500 mcg of blend, 250 mcg of each.

Low — 900–1,200 mcg/day:: Two administrations (four sprays) gives 1,000 mcg of blend, 500 mcg of each. Semax sits in its own low band of 400–600 and Selank in its low band of 450–900. A sensible first-week build that already reaches half of Selank's registered daily regimen.
Standard — 1,200–1,800 mcg/day:: Three administrations (six sprays) gives 1,500 mcg of blend, 750 mcg of each: Semax inside the upper half of its registered 400–900 adaptation range, Selank still in its low band. This is the practical default, and three administrations is also exactly Selank's registered frequency.
The anchor — 1,800 mcg/day:: 900 mcg of each is the single point where both halves sit on a registered-label number at the same time: the top of Semax's registered 400–900 mcg/day adaptation indication, and precisely Selank's registered 900 mcg/day regimen of two drops per nostril three times daily. Reaching it at this concentration takes about seven sprays, so either add a fourth administration and accept 1,000 of each, or mix 24 mg into the same 10 mL (1.2 mg/mL of each) and keep three administrations of two sprays.
High — 1,800–2,400 mcg/day:: Four administrations (eight sprays) gives 2,000 mcg of blend, 1,000 mcg of each — Semax in its high band, Selank in its standard band. The ceiling is 1,200 mcg of each, because that is the top of Semax's own page at any tier: it converges with the single doses given to healthy volunteers in research. Above that only the Selank half still has room, which is where this ratio finally runs out.
What the ratio cannot do:: Almost nothing, which is the point — but two things. It cannot move one component without the other, so a side effect attributable to one can only be addressed by lowering both or switching to separate bottles. And it cannot follow Selank up to its 2,700 mcg/day trial dose: that would carry 2,700 mcg of Semax, more than twice the top of its own page.

Intranasal administration — the primary route

This is the route every published human study of either compound used, and the route both registered products are sold as.

How:: One spray per nostril per administration. Sniff gently rather than sharply — the target is the olfactory epithelium at the roof of the nasal cavity, which is the nose-to-brain surface; a hard sniff drives solution down the throat instead. Alternate which nostril goes first between administrations.
Why not more sprays at once:: Device engineers put the optimum at about 0.1 mL per nostril, and put a whole dose across both nostrils in the 0.1–0.2 mL range. A 0.125 mL pump already exceeds the single-nostril optimum, so two sprays into one nostril is mostly wasted — and one spray per nostril, at 0.25 mL total, is over the two-nostril figure as well. That is why the builder on this page flags the standard administration for dose volume even though it is only two sprays: at this pump size there is no draw that both delivers a useful dose and stays under the runoff threshold. Splitting across nostrils, which this protocol already does, is the mitigation; the alternative is a stronger mix so the dose needs fewer sprays.
Timing:: All administrations in the first half of the day — see Best time to dose above. Three administrations spaced across morning and early afternoon matches Selank's registered frequency while staying inside Semax's window.
Course length:: 14 days is the registered course for both components, then a break. This is one of the few places in the catalog where a cycle length is a label instruction rather than community convention.

Building the bottle

Use the nasal-spray builder on this page — it does this arithmetic live and flags what the mix does and does not establish. The figures here are the standard build.

The standard build:: 20 mg of blend into a 10 mL bottle: 5.5 mL of bacteriostatic water plus 4.5 mL of sterile saline. That gives 1.0 mg/mL of each component, 250 mcg of blend per 0.125 mL spray, and 80 sprays in the bottle — 74 after priming, which is about 12 days at three administrations a day.
Why 5.5 mL of BAC water and not 2:: Bacteriostatic water is 0.9% benzyl alcohol, and diluting it across the bottle dilutes the preservative with it. The common 2 mL fill leaves 0.18%, well under every concentration in documented antimicrobial use. 5.5 mL of 10 gets to 0.495% — as close as you can come to the one approved nasal concentration without going over it, because 0.5% is simultaneously the lowest benzyl alcohol level in any FDA-approved nasal product AND the FDA maximum for a nasal metered spray. That is a knife edge with no margin on either side, and it is worth being blunt about what it buys: the builder still reports this mix as unqualified, and it is right to. Sitting near an approved concentration is not the same as demonstrating that this formulation in this container is preserved, which takes an actual test. The honest reading is that no bacteriostatic-water ratio solves this — it is the argument for a purpose-made nasal preservative, not for tuning the fill.
Build small, twice:: USP <795> gives an aqueous preparation whose preservation is not demonstrated 14 days refrigerated, and a home dilution cannot demonstrate it — though <795> binds compounders and their facilities rather than a person preparing something for themselves, so treat it as the best available yardstick and not a rule being broken. The registered products are preserved with methylparaben, which a bacteriostatic-water dilution does not reproduce. The standard build lands at about 12 days, inside that window. Two arithmetic notes. At the low tier of two administrations a day the same bottle stretches to about 18 days, which is past the date — build a 5 mL bottle instead. And a full 14 days at four administrations a day needs 28 mg of blend, more than one 20 mg vial holds: one vial covers about nine days at that rate, so plan on roughly a vial and a half, or run the course at three administrations.
If you inject instead:: 20 mg + 2 mL is 10,000 mcg/mL of blend, so 18 units on a U-100 syringe is 1,800 mcg — 900 mcg of each, the anchor dose, in a single daily injection. Be aware of what you are choosing: there is no published subcutaneous administration of either compound, in humans or animals, at any dose. The syringe calculator below will do the math; the evidence is behind the nasal route.

Sources:Russian state register (ГРЛС)DOI 10.4236/nm.2013.44035 PMID 18454096 PMID 16523722

Substrate the signal needs

Nutritional cofactor precision

Neither peptide has a cofactor study behind it, and neither depends on a nutrient the way a growth-hormone protocol depends on protein. What is worth supporting is the system the pairing is actually working — cholinergic signaling for the focus half, and the sleep the activating half can disturb.

Reasoned from general neurochemistry and from each component page's own conventions — not from a cofactor study of either peptide or of the blend. Supplement doses are common community ranges.

Supply the substrate — choline

The most common non-peptide addition to a Semax protocol, and the reasoning carries to the blend.

Why:: Choline is the precursor the brain converts into acetylcholine, the neurotransmitter attention and working memory run on. The logic — community reasoning rather than a study — is that raising neurotrophic tone does more when acetylcholine synthesis is well supplied.
What:: Alpha-GPC 300–600 mg/day, or CDP-choline (citicoline) 250–500 mg/day. Alpha-GPC crosses the blood-brain barrier readily.
When:: Morning, with or shortly before the first administration of the day.

Protect the thing Semax can cost you — sleep

The activating half is the reason this blend has a time-of-day rule at all, and sleep is where the cost shows up first.

Why:: Semax's own page names sleep disruption as the reason not to dose late, and the most frequently reported reason to cycle is that the focus effect dulls — which is harder to distinguish from accumulating sleep debt than people expect.
What:: Nothing to add — a constraint to keep. All administrations before mid-afternoon, and if sleep starts to slip, that is the signal to end the course rather than to push through it.
Magnesium, if anything:: Magnesium glycinate 200–400 mg in the evening is the common community addition for sleep quality on activating protocols. General nutrition reasoning, not a Semax finding.

What not to bother with

Two things people add to this stack that the evidence does not support.

A second nootropic peptide from the same family:: The other Pro-Gly-Pro-capped Russian peptides pull on the same design and the same evidence base. Adding a third does not add a mechanism; it adds an unstudied variable to a pairing that is already unstudied.
Anything to "potentiate" the nasal absorption:: The registered products are peptide, water and methylparaben — nothing else. Absorption enhancers sold to be added to home nasal builds have no data behind them for these compounds, and they change a formulation that already cannot demonstrate preservation.

Combinations + timing

Stacking notes + timing windows

This blend already contains the pairing most people are trying to build, so the useful additions come from outside it entirely — and the most useful adjustment, as with every fixed-ratio vial here, is sometimes to stop using the blend for part of the protocol.

Combinations reasoned from complementary mechanisms — not studied head-to-head, and the blend itself has never been tested. Doses are each partner page's own convention.

Separate bottles, when you need to move one half

The one structural limitation of a 1:1 vial, and the fix for it.

Why:: A fixed ratio can only go up or down as a pair. If Semax is too activating at the dose where Selank is working, or you want Selank's 2,700 mcg/day trial dose without carrying more than twice the top of Semax's range, the blend cannot get you there. Neither problem is a flaw in the ratio — they are the price of any pre-mix.
The protocol:: Semax at 600–900 mcg/day and Selank at 900 mcg/day from their own bottles, both intranasal, both in the first half of the day. That is the same total the blend's anchor delivers, with each half independently adjustable.
Cost:: Two bottles, two builds, and two beyond-use dates to track instead of one — which is exactly the convenience the blend was bought for.

A choline source

The standard non-peptide pairing for the focus half.

Why it works:: See the cofactor section above — acetylcholine is the neurotransmitter the attention effect runs on, and it is the one substrate worth deliberately supplying.
The protocol:: Alpha-GPC 300–600 mg orally in the morning, with or shortly before the first administration.

What NOT to stack: the amidate versions of the same two peptides

The most common mistake with this blend is running it alongside what is effectively itself.

Why not:: N-Acetyl Semax Amidate and N-Acetyl Selank Amidate are the same two backbones with terminal modifications. Running them on top of the plain blend is not a stack — it is an unmeasured dose increase of both components at once, with no way to know the effective total because the modified forms' potency relative to the parents is vendor claim, not published data.
The identity problem underneath it:: Several vendors advertise "N-Acetyl" in prose while publishing the plain peptides' CAS numbers, formulas and molecular weights on the same page. If the specs say 813.9 and 751.9 g/mol, you have the plain peptides regardless of what the product name claims. Check the chemistry, not the name.

Reconstitution math

Reconstitution calculator

Calculated for a 1 mL U-100 insulin syringe (100 units/mL).

Peptide per vial

BAC water added

Desired dose

Units per dose

Draw to this mark on a U-100 syringe

This dose contains

Semax900 mcg
Selank900 mcg

Fixed ratio — every draw carries all of the vial's peptides in the same proportions; only the total changes.

Volume per dose: 0.18 mL
Doses per vial: 11
Concentration: 10 mg/mL

One vial lasts

Daily: 11 days
Every other day: 22 days
5×/week: 15 days

Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.

Metered pump

Nasal spray builder

Metered pump · 0.125 mL / spray

Pre-filled for Semax / Selank Blend. Change any field to match your own bottle and vial.

The mix

Peptide into the bottle

Add up every vial going in. Two 30 mg vials = 60 mg.

Finished bottle volume

The volume the bottle holds once mixed.

BAC water used

The rest is topped up with sterile saline.

Top up with 4.5 mL of sterile saline.

Volume per spray

One pump of the bottle. Most meter 0.125 mL, some 0.1 — check the listing.

Target dose

mcg

What you want one administration to deliver.

Doses per day

Sets how fast the bottle is used, which is what the shelf-life check compares against.

Priming sprays

Actuations sprayed to waste to purge air before the pump delivers a full volume.

Per dose

Sprays per dose

sprays

2 × 250 mcg = 500 mcg per dose.

Per spray: 250 mcg
Doses per bottle: 37
Usable sprays: 74
Benzyl alcohol: 0.495 %
Saline to add: 4.5 mL
Concentration: 2,000 mcg/mL

80 in the bottle, minus 6 spent priming.

What this mix does and doesn't establish

Benzyl alcohol lands at 0.495%, below the 0.5% floor of every concentration in documented antimicrobial use. This is unqualified, not proven unsafe: no preservative-efficacy study exists for benzyl alcohol diluted into saline at this level, so under-preservation is an inference from the concentrations regulators accept.
2 sprays is 0.25 mL, over the 0.2 mL a nose takes across both nostrils before it runs back out. Split the dose between nostrils, or rebuild at a higher concentration so the dose needs fewer sprays.

No advisory here means none of these checks fired — not that the mix is qualified.

Research use only. Not for human consumption. Outputs are reference values — verify every measurement independently.

How to read this builder

Six things decide whether a home-built nasal spray works, and four of them are not obvious. Every figure below traces to a primary source.

01It's the inverse of a syringe
With a syringe you pick a dose and read off a volume. With a metered pump the device fixes the volume — one actuation is a constant — so the dose is decided before you ever spray, by how much peptide went into the bottle. Changing your dose means either changing the number of sprays or rebuilding the bottle at a different concentration.
02Priming costs you doses
A fresh pump sprays air until the dip tube and metering chamber fill. Commercial labels call for 4 to 6 actuations to waste (Astelin 4; Hikma fluticasone 6; Ryaltris 6), and instrumented testing shows the air-to-liquid transition finishing around the fifth stroke. This builder defaults to 6, and does not model re-priming after a few days' rest, which labels put at another 2 to 6. A commercial bottle carries overfill to absorb all this. A home-filled one does not, so real yield is at or below what you see here.
03The preservative problem has no comfortable answer
Bacteriostatic water is 0.9% benzyl alcohol, and that figure is qualified for a sealed septum vial — not an open pump bottle whose tip touches the nares and which draws room air into the headspace on every actuation. The lowest benzyl alcohol level in any FDA-approved nasal product is 0.5%, and that product is unit-dose, so it is not even a multi-dose precedent. The FDA's maximum for a nasal metered spray is the same 0.5%. Below that you are under every concentration in documented antimicrobial use; above it you are over the nasal maximum; neat BAC water is 1.8× over. There is no BAC-to-saline ratio that is both plausibly preserved and within approved nasal concentrations, except the single point near 55% BAC. That is the honest shape of the problem, and it is the argument for a purpose-made nasal preservative rather than for tuning a ratio.
04"Unqualified" is not "unsafe" — and the endpoint has been measured
There is no pharmacopeial minimum concentration for a preservative. USP <51> specifies a performance test that a specific formulation in its specific container must pass; concentration is an output of formulation work, not a threshold handed down. So this builder says a mix is unqualified rather than unsafe. What has been measured is the outcome: 18 of 20 unpreserved saline spray containers grew bacteria — S. aureus, P. aeruginosa, E. coli, Proteus — after just three days of home use, while only 3 of 20 dropper bottles did, which points at the pump rather than the saline. Preserved spray with 0.01% benzalkonium chloride came in at 4 of 198.
05Fourteen days, refrigerated
A locally-acting nasal spray is a compounded non-sterile preparation — USP <797> says nasal forms for local application are not required to be sterile, and <795> claims them by name. <795> Table 3 gives an aqueous preparation 14 days refrigerated when preservation is not demonstrated, and 35 when it is. A home dilution cannot demonstrate it, so 14 days refrigerated is the honest default, and that row has no room-temperature option. Worth saying plainly: <795> binds compounders and their facilities, not an individual preparing something for themselves. It is the best available yardstick for what good looks like, not a rule someone at home is breaking.
06The nose has a volume ceiling
Device engineers put the optimum at about 0.1 mL per nostril, noting that higher volumes are prone to drip straight back out, and put a both-nostrils dose in the 0.1 to 0.2 mL range. A 0.125 mL pump already exceeds the single-nostril optimum, which makes dose-splitting a design question rather than a rounding error: if a dose needs several sprays, alternate nostrils, or rebuild the bottle stronger so it needs fewer.

Sources

Brook I, Am J Infect Control 2002;30(4):246-7 (contamination of unpreserved spray containers; note the widely repeated "90.7%" is a typographic artifact — the data is 18/20) · Aydin E et al., BMC Ear Nose Throat Disord 2007;7:2 (preserved-spray contamination) · USP <51> Antimicrobial Effectiveness Testing · USP <795> Table 3 and <797> (beyond-use dating; non-sterile nasal forms) · FDA Inactive Ingredient Database, nasal metered spray · Enbumyst prescribing information · Astelin, Hikma fluticasone and Ryaltris labels (priming) · Aptar device literature (per-nostril volume).

From the studies

Side effects from research

There is no safety study of the combination, so the picture is the two component pictures side by side. Semax's is the better-quantified of the two, though the figures need reading carefully. A review of the Russian clinical literature describes "Semax 1%" — the ten-times-stronger formulation used in acute stroke, not the 0.1% strength this page's build reproduces — as well tolerated with no toxicity or significant side effects, and offers as the indicators of that a discoloration of the nasal mucosa in 10% of patients and a mild rise in blood glucose in 7.4% of patients with diabetes. Those are the only two quantified adverse effects that exist for either compound and they are worth knowing; they are also presented by their source as evidence of good tolerability rather than as a warning, and this page should not invert that. A separate 187-patient study reported a low overall rate of side effects and good tolerance including in older age groups. One interaction is documented and belongs here: Semax forms a complex with high-molecular-weight heparin that has anticoagulant and fibrinolytic properties in vitro, and repeated intranasal dosing stimulated the anticoagulation system in animals. Anyone on an anticoagulant should treat that as an open question.

Selank's picture is thinner but not empty. It is consistently described as non-sedating, and in the study where it was added to a benzodiazepine it reduced that drug's side effects rather than adding its own. Its current registered label carries one specific warning that belongs on any page about it: the product contains methylparaben, which can cause allergic reactions including delayed ones. The claims that it produces no dependence and no withdrawal come from animal work, not from human data.

Two cautions belong to the blend itself. The fixed ratio means a side effect attributable to one component can only be addressed by lowering both or moving to separate bottles. And the preservative situation is genuinely different from the registered products: the current Russian labels use methylparaben at 0.1%, with the unopened bottle refrigerated, the opened one kept at or below 25 °C, and an in-use period of 15 days for Selank and 30 for Semax, while a home nasal build made with bacteriostatic water is preserved — if at all — with benzyl alcohol at a concentration nobody has qualified for this formulation in this container. What has been measured is the endpoint: 18 of 20 unpreserved saline spray bottles grew bacteria after three days of home use, against only 3 of 20 dropper bottles, which points at the pump rather than the liquid. Build small, refrigerate, and keep to the 14-day beyond-use date.

The regulatory picture is worth carrying alongside the safety one, because in the US it is now more specific than "not approved". Both compounds were nominated for the FDA's 503A compounding bulk-substances list and then withdrawn by the nominators after being placed in the significant-safety-risks category, with the FDA noting that compounded drugs containing either may pose an immunogenicity risk for certain routes of administration due to the potential for aggregation and peptide-related impurities. Neither appears on the current 503A or 503B lists. A Belgian federal laboratory, analyzing seized preparations, put the position plainly: these peptides have not completed any clinical trials.

Sources:DOI 10.4236/nm.2013.44035 PMID 15792140 PMID 16634437 PMID 26356395 PMID 31667971 FDA PMID 12032501

As reported in literature

Research dosing ranges

There is no research dose for this pairing, because no study has tested the two together. What follows is the cited evidence behind each component separately, plus the registered label regimens the practical figures above are built on. Read these as the evidence the page leans on, not as doses for the blend. Note how much of it is Russian-language and how little is independently replicated — that is the honest shape of this literature.

Dose	Route	Model	Outcome	Sources:
Any	Intranasal	— no study of the two-peptide combination	No published study has tested Semax with Selank in any model at any ratio; every paper mentioning both ran them as separate arms. The 1:1 vial is market convention, not a studied formulation
400–900 mcg/day	Intranasal	Human — registered Russian label, 0.1% Semax (adaptation / mental fatigue, healthy adults)	2–3 drops per nostril, 2–3× in the first half of the day, 3–5 days. The only primary source stating a Semax dose for people who are not being treated for something	Russian state register (ГРЛС)
900 mcg/day	Intranasal	Human — registered Russian label, 0.15% Selank (anxiety / neurasthenia)	2 drops per nostril 3× daily for 14 days. Note the current label states drops only and carries no microgram figure; 75 mcg per 0.05 mL drop is arithmetic from the registered strength	Russian state register (ГРЛС)
1.0 mg (≈16 mcg/kg)	Intranasal	Human — 16 power-plant operators (Semax)	Reported increases in attention and short-term memory, tested at both the start and end of the working day — but also more false and spontaneous responses, which the authors read as a possible anxiogenic component. English-language but not MEDLINE-indexed, which is why a PubMed-only search misses it	DOI 10.1002/(SICI)1520-6769(199609)19:2<115::AID-NRC171>3.0.CO;2-B
0.25 mg	Intranasal	Human — healthy volunteers, n=11 and n=9 (Semax, EEG sub-studies)	EEG changes. Note this is a different dose and a different population from the attention result above — the two are often conflated	DOI 10.1002/(SICI)1520-6769(199609)19:2<115::AID-NRC171>3.0.CO;2-B
Not stated in the paper	Intranasal	Human — 24 healthy volunteers, 14 of them on Semax; resting-state fMRI (1% Semax)	Measurable changes in default-mode network connectivity	PMID 30225715
Not stated in the abstract	Intranasal	Human — 52 healthy participants; Semax OR Selank OR placebo, separate arms	Altered functional connectivity between the right amygdala and fusiform, inferior/middle temporal and parahippocampal regions. The ROIs were the amygdala and dorsolateral prefrontal cortex — not the default-mode network	PMID 32342318
6,000 mcg/day	Intranasal	Human — 110 patients, post-stroke rehabilitation (Semax)	Plasma BDNF rose; faster functional recovery and improved motor performance reported. The one human measurement of a neurotrophic marker for either compound	PMID 29798983
Not stated	Intranasal	Human — 62 patients, GAD and neurasthenia (Selank vs medazepam)	Anxiolysis comparable to the benzodiazepine, plus antiasthenic and psychostimulant effects	PMID 18454096
Not stated	Intranasal	Human — 60 patients, anxiety (Selank vs phenazepam)	Pronounced anxiolytic and mild nootropic effect; the anxiolytic effect persisted about a week after the last dose	PMID 25176261
Not stated	Intranasal	Human — 70 patients, Selank added to phenazepam vs phenazepam alone	Selank reduced the benzodiazepine's own side effects — attention and memory impairment, asthenia, sedation — during treatment and withdrawal	PMID 26356395
Semax IC₅₀ 10 µM · Selank IC₅₀ 20 µM	In vitro	Human serum (both peptides, compared)	Both inhibit enkephalin-degrading enzymes, Semax about twice as potently. One of several studies that place the two side by side — always as separate arms, never co-administered	PMID 11443939
Various	Intranasal / IP	Rat (Semax, mechanism)	Raises BDNF protein and exon-III mRNA and drives TrkB phosphorylation in hippocampus	PMID 16996037
Various	Intranasal / IP	Rat (Semax, binding)	Specific, calcium-dependent binding in basal forebrain at K_D ≈ 2.4 nM, with raised BDNF there	PMID 16635254
Various	Intranasal	Rat (Selank, mechanism)	Regulates BDNF expression in hippocampus	PMID 18841804
Various	Intranasal	Rat — 6-OHDA parkinsonism model (both, separate arms)	Selank decreased anxiety-like behavior; neither peptide affected motor activity. Tested separately, not combined	PMID 28702721

Quick answers

Frequently asked

Is this the plain blend or the N-acetyl amidate one?

This page is about the plain peptides — Semax and Selank as registered in Russia, and the only versions with any published research behind them. The N-acetyl amidate variants are chemically different compounds with different CAS numbers and masses, sold under nearly identical product names, and PubMed returns zero results for them, so every potency and duration claim made for them is vendor-originated. If you want those, see N-Acetyl Semax Amidate and N-Acetyl Selank Amidate. One practical warning: vendor labeling in this category is unreliable in a specific, checkable way. Several sellers advertise "N-Acetyl" in the description while publishing the plain peptides' chemistry — CAS 80714-61-0 and 129954-34-3, molecular weights 813.9 and 751.9 — on the same page. The chemistry is the answer, not the product name. There is also no registry entry at all for N-Acetyl Selank Amidate: the CAS number vendors publish for it does not resolve, and the PubChem entry named "N-Acetyl Selank" is the acetylated-only free acid, a different compound again.

What is in the vial, and is the ratio standard?

This page assumes 10 mg Semax plus 10 mg Selank, 20 mg total. Unlike most blends here, the ratio genuinely is settled: 1:1 is what almost every vendor sells, with 5 mg + 5 mg as the other common size. Two outliers exist — one vendor sells 10 mg Selank to 30 mg Semax — but both publish self-contradictory pages and neither offers a rationale, so they are poor references. One thing to know regardless: research vials ship as acetate salts, so a nominal 10 mg is about 9.3 mg of free peptide. The 1:1 ratio is unaffected, but every absolute microgram figure runs about 7% optimistic.

Why does this page use the nasal-spray builder instead of the syringe calculator?

Because that is where the evidence is. Every published human study of either compound used the intranasal route, both registered Russian products are nasal drops, and a search of the literature turns up no published subcutaneous administration of either peptide, in humans or animals, at any dose — the non-nasal animal work is intraperitoneal and intravenous. There is also a mechanistic reason the route was chosen: roughly 0.093% of an intranasal Semax dose is reported in brain within two minutes, against about 0.01% intravenously. The syringe calculator is still on the page because both component pages carry the subcutaneous route as a research-peptide convention, and 18 units of a 20 mg + 2 mL mix is the anchor dose in one injection. But the nasal builder is the tool that matches the compound.

What is the ideal daily dose?

1,800 mcg of blend per day — 900 mcg of each — is the one figure with a real anchor under it. At that dose Semax sits at the top of its registered 400–900 mcg/day adaptation range and Selank sits exactly on its registered 900 mcg/day regimen, so both halves are on a label number simultaneously. That point exists only because the ratio is 1:1. In practice, 1,500 mcg/day (three administrations of one spray per nostril at the standard build) is the easy default and 2,000 mcg/day is four administrations; the anchor sits between them, and mixing 24 mg into 10 mL instead of 20 mg lands it exactly at three administrations.

Why can't I just take more per spray instead of spraying more often?

The nose sets the limit, not the peptide. Device engineers put the optimum at about 0.1 mL per nostril and note that larger volumes drip straight back out, so a 0.125 mL pump already slightly exceeds what one nostril takes. Two sprays into the same nostril mostly runs out rather than absorbing. That is why the tiers on this page are stated per day and scale by adding administrations — structurally the same constraint that makes ipamorelin's top tier a frequency tier rather than a bigger injection. The other way to raise the dose is to rebuild the bottle at a higher concentration, which the builder on this page will work out.

Has anyone actually studied the two together?

No. A thorough search returns no co-administration study in any model, at any ratio, in any species. Every published paper that mentions both ran them as separate arms or compared them: the 52-participant resting-state fMRI study gave Semax, or Selank, or placebo; the rat parkinsonism study tested each alone; the one experiment where both appear side by side is an in-vitro comparison of their effect on enkephalin-degrading enzymes in human serum. The pairing rationale is mechanistic inference plus a large amount of user report, and it is worth being clear that those are not the same thing as a result.

Is either half banned in sport?

Neither is named anywhere on the 2026 WADA Prohibited List. The S0 non-approved-substances clause is narrower than it is usually quoted as being — it covers substances with no current approval by any governmental regulatory health authority, and both of these are Russia-registered medicines — so on the plain text S0 does not obviously reach the parent peptides. Semax's only real exposure runs through the S2 chapeau, which also captures substances of similar chemical structure or similar biological effect: it does contain the ACTH(4-7) fragment, though the literature characterises it as non-corticotropic. Selank is a tuftsin analog with no corticotrophin relationship at all. None of this has ever been tested in a case, so a tested athlete should assume risk and check with their federation rather than rely on this reading. The N-acetyl amidate variants are a different matter — approved nowhere, which puts them squarely inside S0.

How long should a course run?

14 days, which is unusual in this catalog for being a label instruction rather than a community convention — it is the registered course length for both components. Semax's registered adaptation indication is shorter still at 3–5 days. After that, a break. The practical build on this page lands at about 12 days per bottle at three administrations a day, which fits inside both the course length and the 14-day beyond-use date a home-mixed nasal bottle gets.

Primary sources

References

PubChem CID 9811102PubChem CID 9811102 (Semax)
PubChem CID 11765600PubChem CID 11765600 (Selank)
DOI 10.4236/nm.2013.44035Kolomin et al., Neuroscience & Medicine 2013;4:223–252 (review: Semax/Selank pharmacology, registered dosing, intranasal BBB penetration, named adverse-effect rates)
DOI 10.1002/(SICI)1520-6769(199609)19:2<115::AID-NRC171>3.0.CO;2-BKaplan et al., Neuroscience Research Communications 1996;19(2):115–123 (intranasal Semax; attention and short-term memory in 16 power-plant operators at 1.0 mg, EEG sub-studies in healthy volunteers at 0.25 mg). English-language, not MEDLINE-indexed
PMID 16996037Dolotov et al., Brain Res 2006 (Semax raises BDNF protein/mRNA and TrkB phosphorylation, rat hippocampus)
PMID 16523722Shevchenko et al., Bioorg Khim 2006 (intranasal brain penetration and rapid degradation; Pro-Gly-Pro the dominant metabolite, rat)
PMID 15792140Gusev et al., Zh Nevrol Psikhiatr 2005 (Semax in chronic cerebrovascular insufficiency, n=187; tolerability)
PMID 29798983Gusev et al., Zh Nevrol Psikhiatr 2018 (Semax at different stages of ischemic stroke, n=110; plasma BDNF measured in humans)
PMID 30225715Lebedeva et al., Bull Exp Biol Med 2018 (intranasal 1% Semax, 24 healthy volunteers; resting-state fMRI — the paper states no mg dose)
PMID 11443939Kost et al., Bioorg Khim 2001 (Semax IC₅₀ 10 µM and Selank IC₅₀ 20 µM against enkephalin-degrading enzymes of human serum)
PMID 18454096Zozulia et al., Zh Nevrol Psikhiatr 2008 (Selank vs medazepam in GAD/neurasthenia, n=62)
PMID 25176261Medvedev et al., Zh Nevrol Psikhiatr 2014 (Selank vs phenazepam in anxiety, n=60; effect persisted ~1 week after dosing)
PMID 26356395Medvedev et al., Zh Nevrol Psikhiatr 2015 (Selank + phenazepam vs phenazepam alone, n=70; Selank reduced the benzodiazepine's side effects)
PMID 18841804Inozemtseva et al., Dokl Biol Sci 2008 (intranasal Selank regulates BDNF expression in rat hippocampus)
PMID 26924987Volkova et al., Front Pharmacol 2016 (Selank affects expression of genes involved in GABAergic neurotransmission, rat)
PMID 16635254Dolotov et al., J Neurochem 2006 (specific brain binding, K_D ≈ 2.4 nM; basal-forebrain BDNF, rat)
PMID 1652713Potaman et al., Neurosci Lett 1991 (entry of the synthetic ACTH(4-10) analogue into rat brain after INTRAVENOUS injection — the source of the ~0.01% figure)
Russian state register (ГРЛС)Russian state register of medicines (ГРЛС) — Semax 0.1% ЛП-№(009449)-(РГ-RU), Semax 1% ЛП-№(010596)-(РГ-RU), Selank 0.15% ЛП-№(010951)-(РГ-RU); registered indications, dose regimens and course lengths
PMID 28702721Slominsky et al., Dokl Biol Sci 2017 (Semax and Selank in 6-OHDA rat parkinsonism — tested as SEPARATE arms, not combined)
PMID 32342318Panikratova et al., Dokl Biol Sci 2020 (52 healthy participants, resting-state fMRI; Semax OR Selank OR placebo — separate arms)
PMID 16634437Liapina et al., Izv Akad Nauk Ser Biol 2006 (comparative anticoagulant effects of proline-containing regulatory peptides incl. Semax and Selank)
PMID 31667971Vanhee et al., Drug Test Anal 2020 (Belgian federal laboratory; seized preparations containing Selank and Semax — "have not completed any clinical trials")
FDAFDA — Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks (semax and selank acetate: nominated, categorised as significant safety risk, then withdrawn; immunogenicity note)
PMID 12032501Brook I, Am J Infect Control 2002;30(4):246–7 (bacterial contamination of saline nasal spray/drop solutions in home use: 18/20 unpreserved sprays vs 3/20 droppers)
WADAWADA Prohibited List 2026 (neither Semax nor Selank is named; S0 covers substances with no approval by any regulator)

Reviewed by Ki Researcher Team · Research use only · Not medical advice · Updated 2026-09-02

Specs

Mechanism

Potential benefits

Best time to dose

Dosing & protocol

Tiered daily ranges (total blend per day)

Intranasal administration — the primary route

Building the bottle

Nutritional cofactor precision

Supply the substrate — choline

Protect the thing Semax can cost you — sleep

What not to bother with

Stacking notes + timing windows

Separate bottles, when you need to move one half

A choline source

What NOT to stack: the amidate versions of the same two peptides

Reconstitution calculator

Reconstitution calculator

Nasal spray builder

How to read this builder

01It's the inverse of a syringe

02Priming costs you doses

03The preservative problem has no comfortable answer

04"Unqualified" is not "unsafe" — and the endpoint has been measured

05Fourteen days, refrigerated

06The nose has a volume ceiling

Side effects from research

Research dosing ranges

Frequently asked

References