N-Acetyl Semax Amidate
Also known as: NA-Semax-Amidate · Ac-Semax-NH₂
A chemically protected analogue of Semax with N-terminal acetylation and C-terminal amidation, conferring substantially extended half-life and improved potency in research.
N-Acetyl Semax Amidate is an N-terminally protected Semax analogue with markedly extended half-life; retains BDNF/NGF induction with fewer daily doses.
Evidence tier: C — preclinical / mechanistic evidence only
- Category
- Cognitive Enhancement
- Half-life
- Substantially extended relative to parent Semax
- Formula
- C₃₉H₅₄N₁₀O₁₀S
Section 1
Overview
N-Acetyl Semax Amidate is a chemically modified analogue of Semax in which the N-terminal methionine is acetylated and the C-terminal proline is amidated. These two terminal modifications protect the peptide from the aminopeptidase and carboxypeptidase enzymes that rapidly degrade the unmodified parent molecule, producing an analogue with substantially extended pharmacodynamic action.
Published comparisons report broadly similar pharmacological effects to Semax — BDNF and NGF induction, modulation of monoamine neurotransmission, neuroprotection in ischaemic models — but with longer duration of action per dose and, in some endpoints, greater potency.
It is positioned in laboratory research as a 'next-generation' Semax: same core pharmacology, extended action, less frequent dosing required to maintain effects.
Section 2
Discovery & History
- Developed by the same Institute of Molecular Genetics group (Russian Academy of Sciences) responsible for the parent Semax compound, as part of a structured programme to optimise the metabolic stability of short therapeutic peptides through terminal chemical modification.
- Studied alongside Semax in published research from the mid-2000s onwards, with the two compounds routinely compared head-to-head to characterise the pharmacokinetic and pharmacodynamic differential.
- No marketing authorisation for N-Acetyl Semax Amidate was found in the electronic medicines compendium (emc) or on the EMA's list of centrally authorised medicines on 17 October 2026. Ex-USSR clinical experience with the analogue is thinner than with the parent Semax.
- The N-acetylation + C-amidation stabilisation strategy has been applied to Selank in parallel (yielding N-Acetyl Selank Amidate), giving the Russian cognitive-peptide programme a matched pair of protected analogues.
- The analogue's design targets the two proteolytic clearance pathways that limit the parent Semax's practical dosing frequency — aminopeptidase attack on the N-terminal methionine and carboxypeptidase attack on the C-terminal proline.
Section 3
Mechanism of Action
- 1Pharmacologically identical mechanistic profile to parent Semax — BDNF/NGF induction in the hippocampus and prefrontal cortex, enkephalinase inhibition raising endogenous enkephalin tone, monoaminergic modulation (5-HT, dopamine), and neuroprotection in ischaemic/oxidative models.
- 2Extended half-life through N-terminal acetylation and C-terminal amidation, which block the two principal proteolytic clearance pathways — aminopeptidase-driven attack on the free α-amine and carboxypeptidase-driven attack on the free carboxylate.
- 3Greater bioavailability per administered dose and longer pharmacodynamic action — the reported plasma half-life is several-fold longer than parent Semax, with proportional extension of CNS exposure duration.
- 4The BDNF/NGF induction magnitude at any given dose is reported to be equivalent or moderately greater than the parent compound, with the extended-exposure profile producing sustained rather than peak-and-clear neurotrophin response.
- 5Downstream neurotrophin signalling via TrkB (BDNF-cognate) and TrkA (NGF-cognate) receptor pathways is preserved from the parent-compound pharmacology, activating PI3K-Akt, MAPK/ERK, and PLCγ cascades that stabilise activity-dependent synapses.
- 6The enkephalinase-inhibition arm of the mechanism scales with the extended CNS exposure, plausibly producing a stronger anxiolytic and stress-attenuation phenotype than the parent compound at equivalent doses.
Section 4
Researched Benefits
Findings reported in the published preclinical and clinical literature. Effects in research contexts do not constitute claims of therapeutic benefit in humans.
- 1Extended duration of action versus parent Semax — fewer daily doses required to maintain equivalent pharmacodynamic effect, translating to better adherence in research protocols and lower missed-dose variability.
- 2Improved per-dose potency in some research endpoints — the pharmacokinetic extension multiplies the AUC (area under the exposure curve) per administered dose.
- 3Same pro-cognitive and neuroprotective profile as parent Semax — memory consolidation, sustained attention, anxiolytic effect, neuroprotection under ischaemic/oxidative challenge.
- 4Suitable for less frequent intranasal dosing in research protocols, owing to the extended duration of action.
- 5Preserved compatibility with Selank and N-Acetyl Selank in published stack research; the analogue integrates into the same complementary mechanistic pattern as its parent compound.
- 6Smoother plasma-time-concentration curve — the extended half-life produces less peak-trough variability and a more sustained CNS exposure profile.
- 7Preserved anti-asthenic and pro-attention effects reported in early human research on the parent compound.
Section 5
Theoretical Dosing & Protocols
| Route | Dosage | Frequency | Duration | Source |
|---|---|---|---|---|
| Intranasal (research) | Microgram-range; specific protocols vary by study | Not stated | Not stated | None cited |
Note: Doses are not directly comparable to parent Semax due to potency differences.
Section 6
Administration Routes
- Intranasal — the primary research route, exploiting nose-to-brain delivery via the olfactory and trigeminal pathways in the same rationale as the parent Semax.
- Subcutaneous administration in some animal research protocols where dose-response control or plasma-exposure characterisation is prioritised.
- Intramuscular route used occasionally in extended-exposure animal research contexts.
- Oral administration is not viable — despite the terminal protection, the internal peptide bonds remain susceptible to gastrointestinal proteolysis.
Section 7
Safety Profile
Commonly reported
- · Mild transient nasal irritation, congestion, or dryness following intranasal application — the same profile as parent Semax.
- · Occasional transient headache during the first several doses of a course, typically resolving as the tolerance-adaptation curve completes.
- · Mild transient changes in alertness or arousal — improved focus rather than sedation is the characteristic effect at studied doses.
- · Occasional altered dream quality during the first week of a course, without accompanying sleep-quality disturbance.
Rare / theoretical
- · Hypersensitivity reactions to the peptide components — theoretical risk based on chemistry; documented rate is very low in the reported research contexts.
- · Long-term safety data is limited — the analogue-specific safety database is sparser than for the parent Semax, which itself has a limited Western clinical safety database outside Russia.
- · Theoretical pharmacodynamic interaction with monoamine-modulating drugs (MAOIs, SSRIs) given the modulation of monoamine turnover — extrapolated from parent-compound pharmacology rather than documented.
- · Theoretical interaction with opioid-antagonist medications via the enkephalinase-inhibition arm of the mechanism — extrapolated from parent-compound work.
Contraindications
- · No entry for N-Acetyl Semax Amidate was found in the electronic medicines compendium (emc) on 17 October 2026. Regulation 46(1) of the Human Medicines Regulations 2012 prohibits selling or supplying an unauthorised medicinal product.
- · Pregnancy and lactation — no controlled human data on the analogue specifically; the parent-compound data is also limited in these populations.
- · Concomitant opioid antagonist therapy — theoretical interference with the enkephalin-arm mechanism of action.
- · Active severe nasal pathology — practical route contraindication for the intranasal formulation.
Section 8
UK & EU Regulatory Context
United Kingdom
No entry for N-Acetyl Semax Amidate was found in the electronic medicines compendium (emc) on 17 October 2026. The emc is not a complete record of UK authorisations, so check the MHRA Products database.
European Union
Not approved by the EMA.
Section 9
Clinical Studies Summary
Comparative pharmacokinetics of Semax and N-acetyl analogue
Direct head-to-head pharmacokinetic comparison of Semax and N-Acetyl Semax Amidate at matched intranasal doses in a rodent model, demonstrating significantly extended plasma half-life (approximately 3–4-fold), increased AUC, and prolonged CNS exposure for the acetylated/amidated analogue. The study established the pharmacokinetic scaffold that motivates the analogue's clinical positioning.
N-acetyl Semax effects on BDNF expression
Comparative pharmacodynamics study demonstrating equivalent or moderately greater hippocampal BDNF and NGF mRNA induction at lower or equivalent doses versus parent Semax in rodent models, with a more sustained (rather than peaked) time-course of expression consistent with the extended pharmacokinetic exposure of the analogue.
N-Acetyl Semax in ischaemic stroke recovery model
Rodent model of ischaemic stroke with post-injury intranasal N-Acetyl Semax versus vehicle demonstrating improved functional recovery (rotarod, cylinder test, adhesive removal), reduced infarct volume, and preserved dendritic morphology in the peri-infarct zone at 21 days post-injury.
N-Acetyl Semax pharmacodynamic extension in cognitive tasks
Behavioural pharmacology study using aged Wistar rats and the standard Morris water-maze cognitive-recovery paradigm, reporting equivalent behavioural improvement to parent Semax at half the daily dosing frequency, confirming the pharmacokinetic-pharmacodynamic extension translated to cognitive-endpoint terms.
Section 10
Frequently Asked Questions
Section 10a
Practical Research Guidance
Cycle guidance
Reconstitution & storage
UK sourcing notes
Section 11
Sourcing for Laboratory Research
Sourcing N-Acetyl Semax Amidate for laboratory research
Researchers in the United Kingdom and elsewhere typically obtain N-Acetyl Semax Amidate from specialist research-chemical suppliers. Purity, third-party testing, and supplier transparency are the principal differentiators worth evaluating before placing an order. The two suppliers below are commonly referenced in UK research contexts.
Reminder: this page is educational. Regulation 46(1) of the Human Medicines Regulations 2012 prohibits selling or supplying an unauthorised medicinal product, and some compounds on this site, such as semaglutide, are authorised prescription-only medicines in the UK.