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Cognitive & neuroPeptideEvidence B2 cited

N-Acetyl Semax

Acetylated Semax Analog

aka N-Acetyl Semax Amidate · NASA · Semax amidate

An acetylated Semax analogue researched for enhanced BDNF upregulation and prolonged cognitive effects.

Molecular wt
855.0g/mol
Formula
C39H54N10O10S
CAS
2920938-90-3
Half-life
1 h
clinical
Tmax
30 min
Route
Intranasal (also subcutaneous)
PubChem
172638603

Sequence

One-letter7 residues

MEHFPGP

Three-letter

Ac-Met-Glu-His-Phe-Pro-Gly-Pro-NH2

Read this before quoting the sequence
Semax is Met-Glu-His-Phe-Pro-Gly-Pro (MEHFPGP), an analogue of ACTH(4-7) extended with Pro-Gly-Pro. The compound PubChem indexes under 'N-acetyl semax' (CID 172638603) is titled 'N-acetyl semax amidate': N-terminally acetylated AND C-terminally amidated. Its formula C39H54N10O10S is consistent with acetylation plus amidation of Semax (C37H51N9O10S). If a vendor supplies a non-amidated N-acetyl Semax, the formula and mass will differ from those given here.
Source ↗

Mechanism of action

N-Acetyl Semax is a synthetic peptide that enhances brain-derived neurotrophic factor (BDNF) expression, which supports neuronal survival and growth. It modulates the activity of the melanocortin receptors, influencing neuroplasticity and cognitive function. The acetylation improves its metabolic stability, allowing for prolonged activity in the central nervous system.

What the evidence actually shows

Grade B

There are limited human trials specifically on N-Acetyl Semax. Existing studies primarily focus on its parent compound, Semax, which has shown cognitive and neuroprotective benefits. More research is needed to confirm these effects in humans for the acetylated version.

Regulatory status

Status
Not approved as a medicine by the FDA, EMA or MHRA. The N-acetyl derivative specifically has no approval or clinical trial record anywhere.
Clinical stage
No clinical trials of N-Acetyl Semax were identified. All clinical data relate to the parent peptide Semax, used and studied clinically in Russia (e.g. PMID 29798983).
UK
research_compound

In the UK, N-Acetyl Semax is considered a research compound and is not approved for medical use by the MHRA.

Source ↗

Pharmacokinetics

Half-life
1 h
Tmax
30 min
Absorption
subcutaneous
Elimination
renal
Washout
1 days
Low-confidence pharmacokinetics
These figures are recorded as clinical rather than measured in a published PK study. Treat them as an order of magnitude. Anything downstream of them — accumulation, steady state, washout — inherits that uncertainty.

Dosing — what backs each figure

N-Acetyl Semax amidate itself has no published human trial. The unmodified parent peptide Semax is a Russian-registered intranasal drug studied in acute ischaemic stroke at 12-18 mg/day of a 1% solution for 10-14 days - roughly thirty times the microgram figures circulated for the acetylated 'nootropic' form. Neither compound has FDA or EMA approval, and no source describes daily nootropic microgram dosing in healthy people.

ClinicalApproved labelling or a published human trial
Commonly circulatedNot established by any study
Dose
200-600 mcg/dose
Frequency
1-2x daily

Why this isn't evidence
N-Acetyl Semax amidate is a modified analogue with no published human dosing, and the 200-600 mcg figure is 20-90x lower than the only real human regimen for the parent peptide (12-18 mg/day intranasally in stroke), so it cannot have been derived from that literature.

This figure is shown because it is what circulates and what people search for — not because it is supported. Cycle lengths in particular tend to be convention copied between compounds rather than anything derived from a compound's own pharmacokinetics.

No established human dose
No approved label or completed human trial establishes a dosing regimen for this compound. Anything presented as a standard protocol for it — anywhere — is someone's convention rather than a finding.

Handling and storage

No compound-specific stability data exists
No peer-reviewed or regulatory stability data specific to N-Acetyl Semax, or to Semax, was located. Only generic lyophilised-peptide handling guidance exists. General peptide handling still applies — reconstitute gently, keep it cold, keep it dark — but any specific figure you see quoted for this compound elsewhere is someone's assumption, not a measurement.
→ Reconstitution walkthrough→ Reconstitution calculator

Safety

Commonly reported
  • ·Mild headache
  • ·Nasal irritation
Rarely reported
  • ·Allergic reactions
Contraindications
  • ·Pregnancy
  • ·Breastfeeding
Drug interactions
  • ·Antidepressants: Potential additive effects on serotonin levels

Reported combinations

Reported as synergistic
  • ·Lion's Mane Mushroom: May enhance neurogenesis
Reported as antagonistic
  • ·Alcohol: May negate cognitive benefits

Combination claims in this dataset are largely unsourced and should be treated as folk knowledge until a citation appears beside them.

References (2)

Data provenance

Chemistry and citations on this page were checked against primary sources on 2026-08-14. Values that could not be verified were left blank rather than filled with a plausible guess.

Could not verify
storage.lyophilized, storage.reconstituted, storage.lightSensitive, reconstitution.solvent, regulatory.wada

Research use only
This profile is educational reference material. It is not medical advice, not a prescription, and not an endorsement of self-administration. Compounds discussed here are research chemicals and most are not approved for human therapeutic use.

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