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N-Acetyl Semax Amidate

Also known as NA Semax Amidate, Ac-MEHFPGP-NH2, Acetylated Semax Amide

N-Acetyl Semax Amidate is a modified analog of Semax, itself derived from an ACTH fragment, carrying both N-terminal acetylation and C-terminal amidation. Those modifications are intended to resist enzymatic degradation. It is widely marketed as the most potent and longest-acting Semax variant, but no published study compares it head-to-head against Semax for potency, duration or bioavailability, so that ranking is a market claim rather than a finding. Used intranasally, it is sold for cognitive enhancement and neuroprotection.

Last updated April 10, 2026

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N-Acetyl Semax Amidate: quick citable summary

N-Acetyl Semax Amidate is listed by PeptaHub as a cognitive peptide with a research only legal-status classification. The page summarizes mechanism, research context, common routes, safety notes, and references for writers and AI answer engines.

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PeptaHub. “N-Acetyl Semax Amidate: Mechanism, Research Context, Safety.” peptahub.com, 2026. https://peptahub.com/peptides/n-acetyl-semax-amidate. Licensed CC BY 4.0.

License: Creative Commons Attribution 4.0 International. Link back to https://peptahub.com/peptides/n-acetyl-semax-amidate.

SAMEAS / EXTERNAL IDS
N-Acetyl Semax Amidate CAS: 2920938-90-3
QUICK ANSWER

What is N-Acetyl Semax Amidate?

N-Acetyl Semax Amidate is a Semax analog with acetyl and amide modifications meant to slow enzymatic breakdown. No published study measures its pharmacokinetics or compares it against Semax, so claims it is more potent or longer-acting are unsourced. The evidence here is all for parent Semax.

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Overview

N-Acetyl Semax Amidate is a modified analog of Semax, itself derived from an ACTH fragment, carrying both N-terminal acetylation and C-terminal amidation. Those modifications are intended to resist enzymatic degradation. It is widely marketed as the most potent and longest-acting Semax variant, but no published study compares it head-to-head against Semax for potency, duration or bioavailability, so that ranking is a market claim rather than a finding. Used intranasally, it is sold for cognitive enhancement and neuroprotection.

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Mechanism of action

N-Acetyl Semax Amidate modulates neurotrophic and neurogenic signaling primarily through upregulation of brain-derived neurotrophic factor (BDNF) and its receptor TrkB, as well as nerve growth factor (NGF) and GAP-43. These effects promote neuroplasticity, synaptic density, and long-term potentiation. It also influences the melanocortin system via partial ACTH-receptor agonism, which affects mood, attention, and stress response. Acetylation and amidation block aminopeptidase and carboxypeptidase cleavage sites, which is the chemical rationale for a longer duration of action, but no pharmacokinetic study of this analog has been published in any species and the specific half-life figures circulated for it are unsourced. Dopaminergic modulation has been reported for the parent Semax in preclinical models.

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Reported study ranges

PurposeRouteReported rangeFrequency
cognitive enhancement and neuroprotection (research)nasal300900 mcgonce to twice daily

Reported ranges are for research context only. Consult a qualified healthcare professional before using any peptide.

Convert N-Acetyl Semax Amidate research-range units

Need to convert mg to mcg, dose volume, or U-100 syringe units? The N-Acetyl Semax Amidate dose calculator is preloaded with these ranges, or use the general dose unit converter.

§ 04

Research summary

Essentially all of the evidence on this page is for the parent compound, Semax, which is approved as a drug in Russia. Semax raised BDNF and TrkB expression in the rat hippocampus (Dolotov, Brain Res 2006), was neuroprotective and antiamnesic in a rat cortical ischemia model (Romanova, Bull Exp Biol Med 2006), and was protective in an MPTP model of dopaminergic lesion (Levitskaya, Neurosci Behav Physiol 2004). A 1997 Russian-language clinical and electrophysiological study examined Semax in acute hemispheric ischemic stroke. No study of N-Acetyl Semax Amidate itself has been published: there is no pharmacokinetic data, no potency comparison against Semax, and no clinical trial. Its status as the preferred variant in community protocols rests on supplier claims.[1][2][3][4][5]

📄This section cites 5 peer-reviewed sources. View all references →
§ 04b

Evidence grading

Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.

preliminary
BDNF and TrkB upregulationDolotov Brain Res 2006: rat hippocampal BDNF and TrkB upregulation, measured with the parent compound Semax. Extension to the acetyl-amidate analog is structural inference, not a measured result
preliminary
Cognitive enhancement and attentionNo controlled trial of either Semax or this analog for cognitive endpoints is cited here, and no specific attention, processing-speed or memory result could be verified. The analog has no dedicated trials at all
preliminary
Neuroprotection after ischemic strokeGusev 1997: Russian-language clinical and electrophysiological study of the parent compound Semax in acute hemispheric ischemic stroke. Romanova Bull Exp Biol Med 2006: rat cortical ischemia model. Semax is approved in Russia for stroke, but all of this is the parent compound, not this analog, and none of it has been independently replicated outside Russia
insufficient
Extended half-life via acetyl/amide modificationsNo pharmacokinetic study of this analog exists in any species. Magrì J Inorg Biochem 2016, previously cited here for receptor selectivity, is in fact a study of how N-terminal acetylation changes copper and zinc coordination and does not measure half-life or receptor activity
preliminary
Dopaminergic neuroprotection (Parkinson's)Levitskaya Neurosci Behav Physiol 2004: MPTP-induced dopaminergic lesion model in rodents; single preclinical study of the parent compound Semax

Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data

§ 05

Side effects

Nasal irritation or congestion
Headache
Fatigue after high doses
Vivid dreams
Mild anxiety at high doses (anecdotal)

Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.

§ 06

Common stacks

Peptides commonly paired with N-Acetyl Semax Amidate for synergistic effects.

§ 08

Sourcing & access

Research compound

N-Acetyl Semax Amidate is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).

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Frequently asked questions

N-Acetyl Semax Amidate is a modified analog of Semax with both N-terminal acetylation and C-terminal amidation. These modifications block cleavage sites and are intended to resist enzymatic degradation. No published study has measured its half-life or compared its potency against Semax, so the widely repeated claim that it is the most potent form is a market claim, not a research finding.

The acetyl and amide modifications block aminopeptidase and carboxypeptidase cleavage sites, which is the chemical reason to expect a longer duration of action. No pharmacokinetic study of either compound is cited here, and no head-to-head comparison of the two has been published, so the specific half-life figures and the claim of stronger BDNF effects are unsourced.

It is administered intranasally using a spray, typically starting at 300 mcg per dose once to twice daily. Common formulations come in 0.1 percent and 0.3 percent solutions. Cycles of 4 to 8 weeks with breaks are standard.

BDNF and TrkB upregulation was shown for the parent compound Semax in the rat hippocampus (Dolotov, Brain Res 2006), and dopaminergic protection was shown for Semax in a rat MPTP model. These are rat findings for Semax, not measurements made with the acetyl-amidate analog, and no human study has measured any of them.

Reported side effects include nasal irritation or congestion, headache, fatigue after high doses, vivid dreams, and mild anxiety at high doses. The side effect profile is generally mild compared to stimulant-based cognitive enhancers.

§ 10

Research references

  1. Influence of the N-terminus acetylation of Semax, a synthetic analog of ACTH(4-10), on copper(II) and zinc(II) coordination and biological propertiesMagrì A, Tabbì G, Giuffrida A, Pappalardo G, et al.Journal of Inorganic Biochemistry, 2016PubMed
  2. Semax, an Analog of ACTH(4-10) with Cognitive Effects, Regulates BDNF and trkB Expression in the Rat HippocampusDolotov OV, Karpenko EA, Inozemtseva LS, et al.Brain Research, 2006PubMed
  3. Neuroprotective and Antiamnesic Effects of Semax during Experimental Ischemic Infarction of the Cerebral CortexRomanova GA, Silachev DN, Shakova FM, Kvashennikova YN, et al.Bulletin of Experimental Biology and Medicine, 2006PubMed
  4. Effectiveness of Semax in Acute Period of Hemispheric Ischemic Stroke (a Clinical and Electrophysiological Study)Gusev EI, Skvortsova VI, Miasoedov NF, Nezavibat'ko VN, et al.Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova (Russian-language), 1997PubMed
  5. The Neuroprotective Effects of Semax in Conditions of MPTP-Induced Lesions of the Brain Dopaminergic SystemLevitskaya NG, Sebentsova EA, Andreeva LA, Alfeeva LY, et al.Neuroscience and Behavioral Physiology, 2004PubMed
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