Semax vs N-Acetyl-Selank
Side-by-side comparison of Semax and N-Acetyl-Selank: mechanism, half-life, dose range, safety profile, and vendor pricing.
Price snapshot
Semax
N-Acetyl-Selank
Semax
Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro, MEHFPGP, 813 Da molecular weight) developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in the 1980s. The compound is derived…
Lowest listed price: $32.90 across 5 listings
Full Semax profileN-Acetyl-Selank
N-Acetyl-Selank is the N-terminally acetylated analog of Selank, a tuftsin-derived heptapeptide used intranasally for its reported anxiolytic and nootropic effects. The acetyl group is claimed to improve stability and…
Lowest listed price: $79.99 across 2 listings
Full N-Acetyl-Selank profileSide-by-side comparison
| Attribute | Semax | N-Acetyl-Selank |
|---|---|---|
| Category | Nootropics | Cognitive |
| Research Stage | Approved in Russia; registered as a prescription intranasal solution | Preclinical (the N-acetyl analog has no dedicated studies); parent Selank has limited clinical use in Russia |
| Mechanism of Action | Primary Mechanism: Multi-Pathway Neurotrophic Activation Semax produces its effects through coordinated activation of multiple neurotrophic, neurotransmitter, and neuroprotective pathways. Unlike conventional nootropics that target a single system (modafinil… | N-Acetyl-Selank is the N-terminally acetylated analog of Selank, a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) derived from the endogenous immunopeptide tuftsin (Thr-Lys-Pro-Arg) with a C-terminal Pro-Gly-Pro tail added to slow enzymatic breakdown.… |
| Half-Life | ~2-3 minutes plasma half-life (functional neurological effects persist 12-24 hours due to BDNF/NGF gene expression changes) | Not established for the N-acetyl analog. Parent Selank has a very short plasma half-life (on the order of minutes, as expected for a small peptide) but produces behavioral effects lasting hours, attributed to active fragments and downstream enkephalin/GABA modulation. N-acetylation is claimed to slow N-terminal degradation and extend duration, but this is unquantified in published literature. |
| Typical Dose Range | 100-900 mcg intranasal daily (0.1% solution: 2-3 drops per nostril 2-3x daily); 1% solution used for acute stroke in Russian clinical protocols | 100-900 mcg |
| Dosing Frequency | Intranasal 1–3 times daily | Once or twice daily (intranasal); some advanced users split into 2-3 doses |
| Administration | Intranasal | — |
| Side Effects | Overall Safety Profile Semax has an excellent safety profile across 20+ years of Russian clinical use. In acute stroke trials, cognitive studies, and pediatric applications, Semax has demonstrated consistent tolerability with minimal adverse event burden. This… | In short Russian clinical trials, parent Selank was generally well tolerated with no serious adverse effects reported [PMID:18454096]. Reported or plausible effects (largely extrapolated to the analog): mild nasal irritation or congestion from the spray,… |
| Molecular Weight | 813.9 Da | ~793.9 g/mol (theoretical: Selank ~751.9 g/mol + N-terminal acetyl, ~+42). Approximate molecular formula C35H59N11O10. |
| Common Vial Sizes | 5mg, 10mg | — |
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Semax: potential benefits
- Rapid BDNF/TrkB upregulation in the hippocampus, supporting synaptic plasticity and learning (PMID: 16996037)
- Neuroprotective, immunomodulatory gene-expression changes in focal cerebral ischemia (middle cerebral artery occlusion) models (PMID: 28255762)
- Cognitive enhancement including improved attention, working memory, and processing speed
- Dopaminergic modulation that may support motivation and executive function (preclinical data)
- Stroke recovery facilitation - accelerated functional recovery and improved Barthel Index in ischemic stroke patients; approved in Russia for ischemic stroke (PMID: 29798983)
- Anxiolytic and anti-asthenic effects reported in Russian clinical use, attributed to neurotrophic and monoaminergic modulation
- Non-addictive cognitive support without tolerance development or withdrawal at standard doses
N-Acetyl-Selank: potential benefits
- Anxiolytic (calming) effects - the most-studied action of parent Selank, including a Russian clinical trial in generalized anxiety disorder [PMID:18454096]
- Nootropic / cognitive support - reported attention and memory benefits in rodent models, linked to BDNF changes [PMID:31625062]
- Stress resilience reported without the sedation, tolerance, or dependence typically seen with benzodiazepines (preclinical framing) [PMID:30255741]
- Possible support during withdrawal states (alcohol, opioid) in animal models [PMID:24913576][PMID:36322304]
- Claimed longer duration vs. plain Selank from N-terminal acetylation - a community/vendor claim not verified in published data
Frequently asked
What's the difference between Semax and N-Acetyl-Selank?
Semax is a nootropics that primary mechanism: multi-pathway neurotrophic activation semax produces its effects through coordinated activation of multiple neurotrophic, neurotransmitter, and neuroprotective…. N-Acetyl-Selank is a cognitive that n-acetyl-selank is the n-terminally acetylated analog of selank, a synthetic heptapeptide (thr-lys-pro-arg-pro-gly-pro) derived from the endogenous immunopeptide tuftsin…. The two differ in mechanism, half-life (~2-3 minutes plasma half-life (functional neurological effects persist 12-24 hours due to BDNF/NGF gene expression changes) vs Not established for the N-acetyl analog. Parent Selank has a very short plasma half-life (on the order of minutes, as expected for a small peptide) but produces behavioral effects lasting hours, attributed to active fragments and downstream enkephalin/GABA modulation. N-acetylation is claimed to slow N-terminal degradation and extend duration, but this is unquantified in published literature.), and typical dose range.
Which has the longer half-life, Semax or N-Acetyl-Selank?
Semax has a half-life of ~2-3 minutes plasma half-life (functional neurological effects persist 12-24 hours due to BDNF/NGF gene expression changes). N-Acetyl-Selank has a half-life of Not established for the N-acetyl analog. Parent Selank has a very short plasma half-life (on the order of minutes, as expected for a small peptide) but produces behavioral effects lasting hours, attributed to active fragments and downstream enkephalin/GABA modulation. N-acetylation is claimed to slow N-terminal degradation and extend duration, but this is unquantified in published literature.. Longer half-lives generally mean less frequent dosing but slower on/off kinetics.
Which is cheaper, Semax or N-Acetyl-Selank?
Lowest listed price on BodyHackGuide: Semax from $32.90, N-Acetyl-Selank from $79.99. Prices are pulled from the vendor listings tracked on BHG and change frequently. See the compare tables on each compound page for the current set of offers.
Can you stack Semax and N-Acetyl-Selank?
Stacking depends on mechanism overlap, safety profile, and goals. Semax and N-Acetyl-Selank should only be stacked after reviewing each compound's individual protocol page, side effect profile, and any published interaction data. Use the BodyHackGuide stack builder for a structured review before combining research compounds.
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Research use only. BodyHackGuide is a research and price-comparison reference. The compounds discussed on this page are not approved by the FDA for human consumption and are sold strictly for laboratory research. Prices shown are pulled from vendor listings tracked on BHG and are subject to change. Every vendor is ranked on the same public, reproducible methodology. See editorial standards and affiliate disclosure.