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N-Acetyl Semax Amidate

Also known as NA-Semax-Amidate, NASA, Ac-Semax-NH2, N-acetyl-(Pro8,Gly9,Pro10)ACTH(4-10) amide

Doubly modified Semax analogue sold by research-chemical vendors, with no published pharmacology of its own.

preclinical Neuro & cognition research chemical

At a glance

Category
Neuro & cognition
Status
research chemical
Route
intranasal or subcutaneous in vendor protocols; no route has been formally studied
Half-life
No published pharmacokinetic data exist for this compound, in any species 1. Vendor claims of a 2-10 hour half-life against 0.5-2 hours for Semax have no traceable source; neither figure is supported by a published human pharmacokinetic study, since none exists for Semax either.
Onset
Unknown; no controlled data on the time course of any effect
Molecular weight
Approximately 855 g/mol, calculated from the parent peptide (813.9 g/mol) plus acetylation and amidation. No independently determined value from a published characterisation of this compound was found.
Sequence
Ac-Met-Glu-His-Phe-Pro-Gly-Pro-NH2 (the Semax sequence with an acetylated N-terminus and an amidated C-terminus)

Not registered as a medicine anywhere and not the substance covered by the Russian registration of Semax - that registration covers unmodified Semax nasal drops. This is a chemically distinct compound created and marketed by peptide vendors, and a PubMed search for it returns no study of it at all 1. No EMA or FDA assessment.

Doping status: Not listed by name; as a non-approved substance it falls under the S0 residual category and is prohibited at all times

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

This is a short entry. There is little or no published research on this compound, so there is correspondingly little to report. Empty dosing or reconstitution sections mean no credible figures exist — not that they were left out.

Mechanism of action

The two modifications are chemically sensible and well understood in general peptide chemistry. N-terminal acetylation removes the free alpha-amino group that aminopeptidases require, and C-terminal amidation removes the free carboxylate that carboxypeptidases require. Both increase overall lipophilicity slightly. Applied to many peptides, this combination measurably extends plasma survival. That is the rationale for the product.

What is missing is any evidence that it does so here, or that the modified peptide retains the activity of the parent. This is not a pedantic objection. Semax is itself defined by its N-terminal methionine, and the mechanistic story told for Semax involves its breakdown to the metabolite Pro-Gly-Pro - a pathway that terminal protection would specifically obstruct. A modification that blocks the degradation route may also block the mechanism. The vendor claim that the modified peptide is 'three to four times more potent per microgram' has no published measurement behind it in either direction.

In short: the pharmacology attributed to this compound is the pharmacology of Semax, transferred by assumption. Semax's own evidence base is weak (see that entry), so the transfer is an extrapolation from an already shaky starting point.

What the research shows

A PubMed search for N-acetyl semax amidate and its variants returns no study of this compound 1. Everything written about it - mechanism, potency, half-life, dosing - is extrapolated from unmodified Semax or asserted by sellers. There is no evidence base to summarise.

Research in humans

No published human studies of any kind: no pharmacokinetics, no safety study, no efficacy trial, no case series. Nothing.

Animal and lab research

No published animal studies of the modified compound were found 1. The animal literature that is cited for it concerns unmodified Semax.

Caveats. The whole entry is a limitation. There is no published characterisation confirming that commercially sold material has the claimed structure and purity; no demonstration that the modifications preserve activity; no pharmacokinetic measurement showing the claimed longer duration; and no toxicology. Certificates of analysis supplied by sellers cannot be independently verified. Absence of reported harm here means absence of anyone looking.

What it is used for

  • Sold and self-administered as a longer-acting alternative to Semax for focus, mental fatigue and post-stroke recovery - claims taken from the parent compound 23, not demonstrated for this one 1
  • No research or clinical use is documented 1

Dosing

Route
intranasal or subcutaneous in vendor protocols
  • No credible dose exists. There is no dose-finding study, no pharmacokinetics and no dose-response data for this compound 1.
  • Vendor protocols typically propose a fraction of the Semax dose on the reasoning that the modified peptide is more potent. That reasoning rests on an unmeasured potency claim, so the resulting numbers are arbitrary.
  • Deliberately left null rather than reproducing figures that would give a fabricated protocol the appearance of authority.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

Intranasal spray or drops (user-reported)

user protocol — not validated

Source: Nootropic forum reports and vendor labelling

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Reported per-administration amountcommonly '1-2 sprays' or a few drops per nostril, once to several times daily
When expressed in microgramsroughly 100-600 mcg per administration is quoted, but the figure depends entirely on the reconstitution
Reported cycledaily use on 'work days', or short courses; no settled schedule

As with the Selank analogue, what actually circulates is a volume rather than a dose. Users describe 'a spray' or 'a few drops per nostril', and the milligrams delivered depend on how the powder was reconstituted and on the pump fitted to the bottle; the same nominal amount appears in the threads as sprays, as drops and as micrograms, and the three do not reconcile. Vendors justify using a fraction of the Semax dose by asserting the modified peptide is 'three to four times more potent per microgram' and lasts far longer, but neither claim has any published measurement behind it 1, and there is no pharmacokinetics or dose-finding study for this compound at all. The numbers are Semax's, adjusted by an unmeasured potency guess.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
5 mg, 10 mg, 20 mg, 30 mg (lyophilised powder, research chemical)
Solvent
bacteriostatic water (0.9% benzyl alcohol) in vendor practice
Storage
Supplier guidance: lyophilised powder at -20 °C protected from light, reconstituted material at 2-8 °C for a few weeks. These are handling conventions, not pharmacopoeia specifications, and no stability study of this compound has been published.

Let the diluent run down the vial wall and swirl rather than shake. Because there is no published analytical method or reference standard for this compound, purity and identity of grey-market material cannot be verified by anyone, including the buyer.

This is administered as nasal drops or spray, not by injection, so there is no syringe volume to work out.

Safety

Side effects

  • Not documented, because no safety study exists 1. This is not a favourable safety profile - it is an empty one
  • By analogy with Semax: nasal irritation with intranasal use, and anecdotal reports of restlessness or irritability. Whether these transfer to the modified peptide is unknown

Do not use if

  • Pregnancy and breastfeeding - no data of any kind
  • Children and adolescents - no data
  • Hypersensitivity to the peptide or to benzyl alcohol in the diluent
  • No toxicology programme has ever been conducted on this compound 1, so no informed statement about who should avoid it is possible

Interactions

Not studied. No interaction data exist for this compound 1.

Sources