N-Acetyl Semax Amidate is Semax with its two ends chemically capped. This guide explains precisely which enzymatic cleavages those caps are designed to block — using the published work that identified them — and is equally clear that the modified peptide itself has never been studied. Reported examples for educational use only, not medical advice.
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NA-Semax Amidate Guide: Available Now
Educational use only — not medical advice. This guide summarizes information reported in published research and community practice for educational purposes. It is not medical advice and not a recommendation to use any compound. Any doses, schedules, or combinations shown are examples of what has been reported, not instructions for you. Many peptides described here are research compounds that are not FDA-approved for the uses discussed and may be investigational or restricted. Effects, risks, and legal status vary; individual needs and results vary. Consult a qualified, licensed healthcare professional before making any decision. Do not use this content to diagnose, treat, or dose yourself.
NA-Semax Amidate at a glance
What it is
Semax (Met-Glu-His-Phe-Pro-Gly-Pro, a synthetic ACTH(4-7) analog extended with Pro-Gly-Pro) carrying an acetyl group on the N-terminus and an amide on the C-terminus. The core seven residues are unchanged; only the two ends are capped.
Researched for
Cognition, memory, attention and neuroprotection — all of it in the parent Semax literature. A PubMed search for the acetylated/amidated analog returns no studies of its own.
Plasma half-life
Not established for the analog, and poorly established for Semax itself. The one indexed measurement — Semax incubated with rat brain plasma membranes — reports a half-life longer than one hour, which is an in-vitro membrane figure rather than a blood half-life. The "few minutes" and "about 30 minutes" numbers commonly quoted are not traceable to a study.
Regulatory status
Not FDA-approved; research use only in the US. Parent Semax is a registered medication in Russia and has no US registry presence — a ClinicalTrials.gov search for Semax returns zero studies.
Educational reference. This page does not publish dose ranges or reconstitution arithmetic.
What it is / mechanism
The useful thing to understand about this compound is what its two modifications are for, and that can be answered precisely rather than with the usual "more stable" phrasing. Semax is Met-Glu-His-Phe-Pro-Gly-Pro, and the published work on how it is broken down identifies the routes specifically. A 2006 study in Amino Acids (PMID 16773243) tracked degradation of uniformly tritium-labelled Semax in the presence of plasma membranes and of glial and neuronal cell cultures from rat basal forebrain, and reported that the splitting away of ME — the N-terminal dipeptide — and of GP — the C-terminal dipeptide — together with formation of pentapeptides, are the predominant processes. An earlier study of Semax at rat forebrain basal-nuclei membranes (PMID 15344653) attributes the breakdown mainly to dipeptidyl aminopeptidases, which cleave Semax successively to the pentapeptide HFPGP and then to the tripeptide PGP. So degradation proceeds by chewing dipeptides off both ends. That is exactly what the two modifications address: acetylating the N-terminus removes the free amino group an aminopeptidase requires, and amidating the C-terminus removes the free carboxyl group a carboxypeptidase requires. The design is coherent and the target of each cap is identifiable in the literature. What follows that, and matters just as much, is that nobody has published a measurement of whether it works. The analog has no indexed studies, so its stability advantage is an inference from Semax's degradation chemistry rather than an observed result — a well-reasoned prediction, not a finding. As for what Semax does once it is present, the parent literature describes blood-brain-barrier penetration and upregulation of BDNF and NGF with associated TrkB signalling, plus modulation of dopaminergic, serotonergic and enkephalin systems. The same 2004 membrane study measured specific, reversible, calcium-dependent binding at rat forebrain basal-nuclei membranes with a dissociation constant of 2.41 ± 1.02 × 10⁻⁹ M and a binding-site density of 33.5 ± 7.9 × 10⁻¹⁵ mol per mg of protein — nanomolar affinity, which is a real and rarely quoted number for this family.
Researched effects
In the parent Semax research and in community reports, the Semax family is associated with improved focus, working memory and mental clarity, a mild alerting effect, and reported neuroprotective and stress-buffering properties; Semax studies describe BDNF elevation and increased TrkB expression, with neurotrophic upregulation building over hours rather than minutes. Two qualifications belong with all of that. The first is that N-Acetyl Semax Amidate has never been the subject of a study, so every effect attributed to it is inherited from a different molecule that happens to share its core sequence. The second is that the bulk of the Semax clinical literature is Russian and was produced in the regulatory environment where Semax is a registered medicine; it is not indexed in the US trial registry, and a search of ClinicalTrials.gov for Semax returns nothing at all. Neither point makes the parent findings wrong. Both mean the evidence is thinner and less independently checked than the confidence of most vendor copy suggests.
Evidence & regulatory status
Evidence for the analog itself: none indexed. A PubMed search for N-acetyl semax returns zero records, and searches for the amidated form return nothing describing this compound. Its properties are extrapolated from the parent Semax literature plus the chemistry of terminal capping.
Evidence for the parent: Semax has a real published record, concentrated in Russian journals and covering cognition, stroke recovery and neuroprotection, plus mechanistic work on receptor binding and degradation that is indexed in PubMed and cited on this page. Note that the field itself studies terminal modification of this peptide — a 2013 paper (PMID 23821053) specifically examined proteolysis of Semax analogues with different N-terminal amino acids by carboxypeptidases — so the modification concept is not a vendor invention, even though this particular modified product is unstudied.
Registry: zero studies for Semax on ClinicalTrials.gov, and none for the analog. Semax's approval is a Russian national registration, not an FDA one, and the acetylated/amidated form is not separately registered anywhere.
Regulatory: not FDA-approved and sold in the US for research use only. Not explicitly named on the WADA Prohibited List, though non-approved substances can fall under the catch-all category S0 — athletes should verify current rules directly rather than rely on a guide page.
Research-use: provided strictly as a research chemical for laboratory and educational purposes. Content here describes what is reported in studies and community discussion and is not a recommendation for human use.
Research timeline
Dated milestones taken from the primary records: the molecule's discovery, its first registered human study, the trials that shaped the evidence and the regulatory decisions. Each entry links to the record it comes from.
The published research behind N-Acetyl Semax Amidate is research on unmodified Semax, which begins in 1997 and is listed on the Semax guide; a PubMed search finds no study of the acetylated and amidated molecule itself. PMID 9173745
Russian researchers, using tritium-labelled Semax on rat brain membranes, find it is broken down mainly by enzymes that clip pairs of amino acids from its free starting end, which is the end the N-acetyl cap is meant to protect. PMID 15344653
Records checked Oct 4, 2026
Claims at a glance
The claims most often made about this compound, each with the strongest kind of evidence we found for it. The grade says what was studied, not whether the claim is true; the line beside it says what that study showed.
Lasts longer and works better than plain SemaxNo study found. Never measured. On rat brain membranes, Semax was broken down mainly from its starting end, the end the acetyl cap covers, but no study has tested whether the capped form lasts longer or does more. PMID 15344653
Speeds recovery after strokeNo study found. In stroke rehabilitation, patients also given Semax regained everyday function faster and more fully than those who were not, with less effect on weakness; they were not randomised. PMID 29798983
Lifts mood and motivationNo study found. In an open study of people with motor neurone disease, Semax improved self-rated quality of life through mood and motivation, while the disease measures did not change. PMID 18379501
Works as an antidepressantNo study found. In chronically stressed rats, Semax restored interest in sweet water and protected brain BDNF, but did not change the classic swim-test measure of despair. PMID 39442746
Treats ADHDNo study found. The claim traces to one 2006 hypothesis paper proposing that Semax might help; no study has tested it in ADHD, in animals or in people. PMID 16996699
Grades checked Oct 7, 2026
A printable reference sheet with the compound's key facts, storage guidance and a vial record comes with All-Access Lifetime.
Half-life & pharmacokinetics
No half-life has been published for N-Acetyl Semax Amidate, and the figures commonly quoted for it and for its parent do not hold up well when traced. An earlier version of this page said standard Semax clears within minutes and that the acetyl/amide modification extends that to roughly 30 minutes. Neither number could be traced to a study, and the one indexed measurement points the other way: the 2004 study of Semax at rat forebrain basal-nuclei plasma membranes (PMID 15344653) reports the peptide's half-life in the presence of those membranes as longer than one hour. That figure needs its context stated rather than swapped in as a replacement — it is an in-vitro measurement against a membrane preparation, not a plasma half-life in a living animal, and the two are not interchangeable. The honest summary is that Semax's in vivo circulating half-life is not something the indexed literature settles, and for the capped analog there is no measurement at all. What can be said with confidence is directional: capping both termini blocks the specific exopeptidase cleavages that the degradation studies identify as dominant, so a longer functional life than Semax is the reasonable expectation. Expectation is the correct word. Separately, and independent of clearance, the downstream neurotrophic changes reported in Semax studies build over hours and outlast the peptide's presence, so circulating half-life is not a good proxy for duration of effect in this family.
Reported side effects & toxicology
Human safety data for NA-Semax Amidate specifically does not exist, and most of what is said about its tolerability is inherited from the parent Semax. Reported and anticipated effects include overstimulation or anxiety at higher amounts, irritability or disrupted sleep, and — with intranasal use — nasal or throat irritation. Subcutaneous use may produce local injection-site reactions such as redness, swelling or discomfort. It is worth adding one point that the stability rationale implies: if the modifications do what they are designed to do, the analog persists longer than Semax, which means any effect — wanted or unwanted — plausibly persists longer too. That cuts both ways and is not accounted for in protocols copied across from Semax. None of this substitutes for professional medical evaluation.
Storage & handling
Lyophilized (freeze-dried) powder is reported to be stable refrigerated at 2–8 °C and can be kept frozen for longer-term storage; keep it away from light and moisture until reconstituted.
Once reconstituted with bacteriostatic water, refrigerate at 2–8 °C and use within a few weeks; avoid freezing the reconstituted solution and do not shake. Bacteriostatic water's benzyl alcohol preservative is what allows repeated withdrawals from one vial — sterile water has no preservative and is intended for single use.
References
Primary sources for this guide: PMID 16773243 (Amino Acids, 2006) for the degradation pathway showing N-terminal ME and C-terminal GP removal as the predominant processes; PMID 15344653 (Bioorganicheskaia Khimiia, 2004) for Semax receptor binding at rat forebrain basal-nuclei membranes (Kd 2.41 ± 1.02 × 10⁻⁹ M, Bmax 33.5 ± 7.9 × 10⁻¹⁵ mol/mg protein), the dipeptidyl-aminopeptidase degradation route to HFPGP and PGP, and the greater-than-one-hour membrane half-life; PMID 23821053 (Doklady Biological Sciences, 2013) for proteolysis of Semax analogues with modified N-termini by carboxypeptidases; and PMID 16637290 (2006) for the tritium-labelling method used across this degradation work. Registry status checked against ClinicalTrials.gov. Where an earlier version of this page carried half-life figures of a few minutes for Semax and about 30 minutes for the analog, those have been withdrawn rather than corrected silently, because neither could be traced to a source.
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Quick answers about guide scope, access, and educational use context.
How is N-Acetyl Semax Amidate different from regular Semax?
It is the same seven-residue Semax sequence with both ends capped — an acetyl group on the N-terminus and an amide on the C-terminus. The core peptide is unchanged. The purpose of the caps is to block enzymatic breakdown, and the published degradation work makes it possible to say exactly which breakdown: studies of Semax report that the predominant routes are removal of the N-terminal ME dipeptide and the C-terminal GP dipeptide by exopeptidases, and each cap removes the free terminus one of those enzyme classes needs. The design is sound in principle. Whether it delivers has not been measured, because the modified analog has no published studies of its own.
Which enzymes and which bonds do the modifications actually block?
Exopeptidases that work inward from the ends. A 2006 study in Amino Acids (PMID 16773243) tracking labelled Semax in the presence of brain plasma membranes and glial and neuronal cultures found that splitting off ME from the N-terminus and GP from the C-terminus were the predominant degradation processes. A 2004 study (PMID 15344653) attributes the breakdown mainly to dipeptidyl aminopeptidases, cleaving Semax to the pentapeptide HFPGP and then to the tripeptide PGP. N-terminal acetylation eliminates the free amino group an aminopeptidase binds; C-terminal amidation eliminates the free carboxyl group a carboxypeptidase binds. That the field studies this deliberately is confirmed by a 2013 paper on the proteolysis of Semax analogues with different N-terminal residues by carboxypeptidases (PMID 23821053).
What is the half-life of N-Acetyl Semax Amidate?
It has not been measured. Neither, in a form worth quoting, has the parent's. The one indexed figure is from Semax incubated with rat forebrain plasma membranes, where the half-life was reported as longer than one hour — an in-vitro membrane measurement, not a blood half-life, and not transferable to either. The commonly circulated "a few minutes for Semax, about 30 minutes for the amidate" pairing appeared on an earlier version of this page and has been withdrawn because neither number traces to a study. Note also that in this family the neurotrophic effects reported downstream build over hours and outlast the peptide itself, so half-life would be a poor guide to duration of effect even if it were known.
Has N-Acetyl Semax Amidate been studied in humans?
No, and not in animals either — it has no indexed studies at all. Everything attributed to it comes from the parent Semax. Semax itself has a genuine published record, largely Russian, where it is a registered medication; it is not in the US trial registry, and a ClinicalTrials.gov search for Semax returns zero studies. So the evidence chain runs: a real but geographically concentrated literature on one molecule, plus a chemically reasonable prediction about a modified version of it that nobody has tested.
What is the molecular weight of N-Acetyl Semax Amidate, and why does it differ from Semax?
The two caps change the mass in a defined way. Acetylation of the N-terminus adds an acetyl group in place of a hydrogen, a net addition of about 42 daltons. C-terminal amidation replaces the terminal hydroxyl with an amide, a net change of about −1 dalton. So the capped analog runs roughly 41 daltons heavier than the parent heptapeptide. This is worth knowing when reading a certificate of analysis: a mass-spectrometry result should match the capped mass, not Semax's, and a report showing the parent's mass on a product sold as the amidate is a discrepancy rather than a rounding difference.
Is it taken as a nasal spray or an injection?
Both routes are reported, and intranasal is the more commonly described one — metered sprays around 0.1% or 0.3% delivering roughly 300 mcg per pump. Subcutaneous injection is also used. This guide describes reported practice; it is not a recommendation to use it by either route.
What dose is commonly reported?
None is established. The daily amounts and cycles in reported protocols carry over from Semax protocols, and this page does not reproduce them. Because no study has compared the capped analog to the parent, there is no measured basis for adjusting between them.
Is N-Acetyl Semax Amidate legal or approved?
It is not FDA-approved and is sold in the US for research use only. The parent Semax is a registered medication in Russia, but the acetylated and amidated analog is not separately registered there or anywhere else. It is not explicitly named on the WADA Prohibited List, though non-approved substances can fall under category S0 — athletes should check current rules directly rather than rely on this page.
Is there a certificate of analysis worth checking for this compound?
Yes, and the mass is the field to read first. Because the identity of this product is defined entirely by its two terminal caps, a mass-spectrometry result is what distinguishes it from plain Semax — the capped form should run roughly 41 daltons heavier. Purity by HPLC tells you how much of the sample is the main peak; it does not tell you that the main peak is the capped molecule rather than the uncapped one. Our explainer on reading a peptide certificate of analysis covers which fields on a report are checkable and which are not.
Compliance and trust notes
Educational content only; no personalized health or outcome claims.
No personalized use recommendation outputs.
Use this material for general learning and research-context literacy.
Reading an NA-Semax Amidate certificate of analysis
A certificate of analysis (COA) is a laboratory’s report on one sample of one batch. The single most useful thing to know about it is that purity and identity are two separate results that fail in different ways. A high purity figure says the sample was mostly one substance; it does not say that substance was NA-Semax Amidate. Identity — normally a mass-spectrometry result matching the expected molecular weight — is what establishes what the material actually is, and a certificate reporting purity alone has not answered that question.
Two further limits are worth holding onto. Mass per vial is its own test: a vial can be 99% pure and still contain less material than the label claims. And sterility, endotoxin, heavy metals and residual solvent screening are separately commissioned tests, usually priced individually — so a “third-party tested” badge asserts none of them unless the certificate names them. Check that the batch or lot number on the document matches the vial in front of you; an unmatched certificate describes someone else’s material.
Specific to NA-Semax Amidate
The same identity problem as the Selank variants, with the same arithmetic. Plain Semax is C37H51N9O10S at monoisotopic 813.3480; the acetylated-and-amidated product is C39H54N10O10S at 854.3745 ([M+H]⁺ 855.382), 41.03 Da heavier. A certificate reporting a mass near 813 has identified plain Semax whatever the label says, and a purity percentage cannot distinguish the two at all.
Medibact does not test, endorse or resell peptides, and publishes no rating of any laboratory. How to read a peptide certificate of analysis walks through the document section by section, and what each COA field establishes covers the field-by-field detail and the laboratories that publish their methods.
You’ll need bacteriostatic water
The diluent for reconstituting NA-Semax Amidate
Reconstitution is volume arithmetic — it assumes a lyophilized vial is dissolved in bacteriostatic water, which is sterile water preserved with 0.9% benzyl alcohol. The preservative is what allows a vial to be entered more than once; plain sterile water carries none and is single-entry by design. Medibact supplies USP-grade Bacteriostatic Water for Injection in a 30 mL multi-dose vial, made in the United States and shipped from the United States, for research use only. One 30 mL vial covers 30 reconstitutions at 1 mL each, 15 at 2 mL, or 10 at 3 mL — division only, not a dosing recommendation.
Educational use only — not medical advice. This guide summarizes information reported in published research and community practice for educational purposes. It is not medical advice and not a recommendation to use any compound. Any doses, schedules, or combinations shown are examples of what has been reported, not instructions for you. Many peptides described here are research compounds that are not FDA-approved for the uses discussed and may be investigational or restricted. Effects, risks, and legal status vary; individual needs and results vary. Consult a qualified, licensed healthcare professional before making any decision. Do not use this content to diagnose, treat, or dose yourself.
