Quick summary
N-Acetyl Semax is an acetylated Semax derivative with enhanced proteolytic stability and CNS bioavailability. It rapidly elevates BDNF and activates serotonergic and dopaminergic systems, with an estimated half-life of 15-60 minutes versus 5-15 for standard Semax.
Overview
N-Acetyl Semax is an acetylated derivative of Semax, a synthetic heptapeptide analogue of the ACTH(4-10) fragment developed in Russia. The N-terminal acetylation modification confers greater proteolytic stability compared to unmodified Semax, extending the effective duration of action and enhancing CNS bioavailability following intranasal administration. It occupies an intermediate potency position between standard Semax and the more stable N-Acetyl Semax Amidate, and is used as a nootropic, neuroprotective, and neurorestorative research compound.
Mechanism of action
N-Acetyl Semax's mechanism of action involves multiple parallel pathways. It rapidly elevates brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the hippocampus, supporting neuroplasticity and long-term potentiation. It activates serotonergic and dopaminergic neurotransmitter systems, contributing to mood stabilization and motivational tone. Interactions with melanocortin receptors (MC1R, MC4R) are proposed based on its ACTH peptide origin. Additionally, Semax inhibits enkephalinase enzymes that degrade endogenous neuropeptides, prolonging their activity. Intranasal administration allows direct transport along the olfactory nerve to the CNS, bypassing the blood-brain barrier. The N-acetyl modification blocks N-terminal exopeptidase cleavage, extending half-life to an estimated 15–60 minutes versus 5–15 minutes for unmodified Semax.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| cognitive enhancement and neuroprotection research | nasal | 200–600 mcg | once or twice daily | Typical nasal spray dose is 200–600 mcg per session. Start at 200 mcg. Effects reported to last 6–12 hours. Cycle 4–8 weeks on, 2–4 weeks off. |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Semax has accumulated substantial preclinical evidence in Russian and Eastern European literature for neuroprotection in ischemic stroke, traumatic brain injury, and neurodegenerative conditions, with approved use in Russia and Ukraine. Rodent studies show rapid upregulation of BDNF transcription within 20 minutes of intranasal administration, with hippocampal BDNF protein levels elevated for up to 24 hours. N-Acetyl Semax specifically has been studied in gene expression analysis of neural tissue, demonstrating broader transcriptional network modulation than standard Semax. Human trials are limited to the base Semax compound; N-Acetyl Semax has no completed clinical trials as of 2026.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with N-Acetyl Semax for synergistic effects.
Legal status
Not FDA-approved in the US. Classified as a prescription medication in Russia and Ukraine for neurological conditions. Available from research peptide suppliers in the US and EU without prescription, primarily for research purposes.
Sourcing & access
Research compound
N-Acetyl Semax 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).
Frequently asked questions
N-Acetyl Semax is an acetylated derivative of Semax, a synthetic heptapeptide ACTH(4-10) analog developed in Russia. The N-terminal acetylation confers greater proteolytic stability and enhanced CNS bioavailability versus unmodified Semax. It sits between standard Semax and N-Acetyl Semax Amidate in potency.
It elevates brain-derived neurotrophic factor (BDNF) and TrkB in the hippocampus, activates serotonergic and dopaminergic systems, interacts with melanocortin receptors, and inhibits enkephalinase enzymes. Intranasal administration delivers it directly to the CNS via the olfactory nerve.
Side effects include nasal irritation or congestion, headache, fatigue after initial stimulation, irritability at high doses, and sleep disturbance if dosed late in the day. It is not FDA-approved and is available as a research compound; human clinical trials are limited to the base Semax compound.
It is typically administered as a nasal spray at 200 to 600 mcg per session, once or twice daily. Effects are reported to last 6-12 hours. Common cycling protocol is 4-8 weeks on followed by 2-4 weeks off.
Research references
- Semax peptide and its N-acetylated analogue: neuroprotective effects in ischemiaPubMed
- Semax and BDNF expression in the hippocampus: neurotrophin modulationPubMed
- N-Acetyl-Semax Amidate cognitive enhancement in healthy volunteersPubMed
- Semax analogs and ACTH(4-10) derivatives: structure-activity relationshipsPubMed