Skip to content
PeptideAI
Anecdotalcognitionmoodenergy

N-Acetyl Semax Amidate

A terminally capped version of Semax that resists breakdown for longer, so it hits harder per milligram and lasts through a working day instead of a morning.

Also known as NA-Semax-Amidate, NASA, N-acetyl semax amide, NA-Semax

Anecdotal — Community reports without controlled evidence. Treat the confident dosing charts accordingly.

There are no published human or animal trials on the acetylated-amidated form specifically. Everything here is extrapolated from Semax data plus well-established peptide chemistry about terminal capping, and from a large volume of consistent user reporting. Confident forum consensus is not the same as data.

How it works

Acetylating the N-terminus and amidating the C-terminus is a standard peptide-stability trick: it removes the free charged ends that exopeptidases recognise. The pharmacophore is unchanged, so everything said about Semax and BDNF, NGF and monoamine turnover applies here. The practical consequence is a longer window of exposure per dose and a higher effective potency, which is why sensible dosing is roughly a third to a half of the Semax dose. There is no published human pharmacokinetic study on the modified form - the potency claims come from vendor characterisation and user reports, not from a paper.

Targets: BDNF, NGF, TrkA/TrkB signalling, Dopaminergic and serotonergic systems

Dosing

ProtocolDoseFrequencyRoute
Standard intranasal protocolMorning only. The longer duration is exactly why afternoon dosing wrecks sleep.100 mcg – 300 mcgonce dailyintranasal
Aggressive cognitive-load protocolMorning.300 mcg – 600 mcgonce dailyintranasal
  • · Deliberately lower than Semax dosing. Users who transfer their 600 mcg Semax dose straight across almost always report irritability and a flat, wired feeling.
  • · Used for short high-demand stretches such as exams or deadlines. Not intended to be sustained past a couple of weeks.

Titration

Start at 100 mcg. This compound is potent enough per milligram that most people never need to go above 300 mcg.

Cycling

2-4 weeks on, 2-4 weeks off. Because the exposure per dose is longer, tolerance and the associated emotional flattening tend to appear sooner than with plain Semax.

Work out your exact syringe units →

Pharmacology

Half-life
Not established in humans. Claimed to be several-fold longer than plain Semax on the basis of the blocked termini; there is no published PK study to cite.
Onset
20-40 minutes intranasally, with a subjectively longer plateau than Semax - most users report 6-10 hours of effect.
Routes
intranasal, subcutaneous
Molecule
Synthetic heptapeptide, N-terminally acetylated and C-terminally amidated Semax
Sequence length
7 amino acids
Molecular weight
855 Da

Handling

Diluent
Bacteriostatic water
Typical mix
2 or 3 mL
Vial sizes
5, 10, 30 mg
Lyophilised
Room temperature short term; fridge or freezer for long-term storage.
Reconstituted
Refrigerated, about 30 days. The capped termini make it more chemically robust than Semax but not immune to it.
Light sensitive
Yes — keep it out of the light

Intranasal — usable, with a caveat

Nasal is the route this modification exists for - the N-acetyl and amidate groups are there to slow degradation at the mucosa and extend duration relative to plain Semax. That rationale is chemically sound and widely repeated, but there is no published human pharmacokinetic comparison of the two, so the claimed potency multiples circulating in forums are estimates rather than measurements.

Mixing

A 10 mg vial in 2 mL gives 5 mg/mL; a 0.05 mL spray then delivers 250 mcg. Do the arithmetic before you fill the bottle, not after.

Side effects

  • commonIrritability and overstimulation— More frequent than with plain Semax because people carry the old dose over.
  • commonInsomnia— The long tail means even a midday dose can reach bedtime.
  • commonNasal irritation
  • uncommonEmotional blunting or apathy after weeks of continuous use— Resolves within days of stopping.
  • uncommonHeadache

Do not use if

  • Pregnancy and breastfeeding - no safety data.
  • Active psychosis, mania or stimulant-sensitive anxiety.
  • Concurrent high-dose plain Semax - you are dosing the same molecule twice.

Combining it

  • redundantsemax — The same pharmacophore in a more stable wrapper. Choose one.
  • synergyn-acetyl-selank-amidate — The modern version of the Semax/Selank pairing, matched for duration.
  • cautionnoopept — Overlapping neurotrophic and stimulating effects; combining reliably produces headaches in a subset of users.

What to monitor

  • · No bloodwork established.
  • · Watch sleep quality specifically - it is the earliest and most reliable sign the dose is too high or too late.

Legal status

Not approved anywhere. Sold exclusively as a research chemical.

Mechanism in depth

There is no separate mechanism here, and it is worth being blunt about that. The pharmacophore is identical to Semax; acetylation and amidation are stability modifications, not activity modifications. What they change is exposure. The published Semax degradation work shows the dominant breakdown routes are removal of Met-Glu from the N-terminus and Gly-Pro from the C-terminus - both exopeptidase reactions, and both are exactly what capping blocks. So the stability argument is mechanistically sound and rests on real chemistry about the parent molecule. What does not exist is any measurement of how much longer the capped version actually survives in a person, how much more of it reaches brain, or whether the receptor interaction is unchanged. Acetylating an N-terminal methionine is not a neutral act at every receptor, and nobody has run the binding assay on this analogue. The practical consequence that users report consistently - roughly a third to a half of the Semax dose produces a comparable effect for longer - is the only evidence there is, and it is user reports.

What usually goes wrong

One failure mode dominates everything else: dose transfer. Someone runs 600 mcg of Semax twice daily, buys the acetylated version, doses the same, and spends a week wired, irritable and flat with wrecked sleep, then concludes the compound is bad. It is not bad; it is three to five times the dose they needed. Start at 100 mcg regardless of your Semax history. The second failure is treating the longer duration as free - it is not, it is exposure, and the emotional blunting that shows up after two to three weeks of continuous use appears sooner on this than on plain Semax for exactly that reason. The third is the vendor problem: there is no reference standard for this molecule, no pharmacopoeial monograph and no registered product anywhere, so the identity and purity of what arrives is entirely a matter of trusting your supplier's certificate of analysis. Since the capping is the whole value proposition, an incompletely capped batch is functionally just expensive Semax and you would never know.

Titration ladder

  1. 100 mcgDays 1-4 — One morning intranasal dose. Yes, this feels absurdly low if you are coming from Semax. That is the point - most bad first experiences come from carrying the Semax dose across.
  2. 200 mcgDays 5-10 — Hold here for a week. A large fraction of users never need more than this.
  3. 300 mcgWeek 2-3 — Practical ceiling for sustained use. Beyond this, irritability and flatness become the dominant reported effects.
  4. 600 mcgShort bursts only — The aggressive cognitive-load dose. Reasonable for a two-week deadline stretch, not for a lifestyle protocol. Expect the sleep cost.

Bloodwork worth running

MarkerWhenWhy it matters
Resting blood pressure and heart rateBaseline, then 2 and 8 hours after a dose during the first week.The longer exposure means the sympathomimetic-feeling component runs for most of the waking day rather than a morning. This is the measurable version of the overstimulation that is the number one complaint on this compound.Act if: Halve the dose if resting heart rate is persistently 10-15 bpm above baseline in the evening. An evening elevation on a morning-only dose is the specific signature of overdosing this analogue.
Sleep latency and total sleep timeEvery night for the first two weeks, using a wearable or a written log rather than recall.Not a blood marker, but it is the single most sensitive readout on this compound and worth tracking with the same rigour as a lab. The 8-12 hour tail means a morning dose can still be present at bedtime.Act if: Sleep latency extending beyond about 30 minutes, or total sleep dropping more than 45 minutes below your baseline, means the dose is too high. Nothing this compound gives you is worth that trade.

Pharmacokinetics

Crosses blood-brain barrier
partial
Metabolism
Presumed endopeptidase cleavage of the internal peptide bonds, since the exopeptidase routes that dominate plain Semax degradation are chemically blocked. There is directly relevant published work: a Russian group measured the proteolytic stability of acetylated Semax in various biological media, which is the closest thing to evidence this analogue has.
Elimination
Assumed renal excretion of fragments. Never measured.

Receptor targets

  • Same basal forebrain binding site as Semax — Never measured for the modified peptide. Assumed equivalent to Semax on the basis that the core sequence is unchanged - an assumption, not a finding

    Presumed identical BDNF induction. No study has confirmed this for the acetylated-amidated form.

  • BDNF / NGF expression — Indirect

    Assumed identical to Semax. Never demonstrated for this analogue specifically.

  • Melanocortin MC2R (adrenal) — No activity expected - the steroidogenic residues are absent from the 4-10 core

    No cortisol release, same as Semax.

What to expect, and when

20-40 minutes to first noticeable effect intranasally. Peak subjective effect around 1-2 hours. A plateau most users describe as 6-10 hours, with a tail that can reach 12. Sustained mental stamina rather than acute stimulation becomes the dominant feature by day 3-5, which is faster than plain Semax. Tolerance to the acute feel and the first hints of emotional flattening typically appear at 10-14 days of continuous use - roughly a week earlier than plain Semax at equivalent effect. Nothing is known about what happens past a month because nobody has studied it.

Stacking and comparisons

The duration-matched pairing with N-Acetyl Selank Amidate is the most coherent stack in this class: both run 8-12 hours, so you dose once in the morning and the arousal and the anxiolysis rise and fall together instead of one outlasting the other. That matched timecourse is a genuine advantage over the original Semax/Selank pair, where Selank fades first and you get a stimulated evening. Do not run this alongside plain Semax - it is the same molecule and you are simply double-dosing with no way to know your total. Noopept plus this compound is the reliable headache generator; the overlap in mechanism is total and the stimulation is additive. Caffeine is best kept low or skipped on the days you dose this, because the long tail means there is no window where the peptide is out of the way.

Against plain Semax: longer, stronger per microgram, harder to fine-tune, and evidentially weaker - Semax at least has Russian registration and human stroke data behind the parent molecule, while this analogue has none of its own. If you want to know whether the Semax pharmacophore does anything for you, test it with plain Semax first, where the dose-response is better understood and you can stop mid-day. Move to the capped version only if the duration is the specific problem you are solving. Against N-Acetyl Selank Amidate: opposite effects on arousal, same duration, designed to be run together. Against Noopept: Noopept is orally active, dirt cheap, has a Russian registration and a comparative human trial, and is much milder. If cost or needle-free convenience matters, Noopept is the more defensible choice and this is the more potent one. The honest summary is that this compound sits in the awkward position of being the most popular nootropic peptide of the last few years with zero primary evidence of its own.

Rough cost

$20–$60/month. A 30 mg vial runs roughly 45-80 USD. At 200 mcg daily that is 150 days of use, so the per-month cost is low - typically 15-25 USD. The compound is more expensive per milligram than plain Semax and considerably cheaper per day, because you use so much less of it. Vial-for-vial price comparisons with Semax are misleading for exactly this reason.

Genuinely uncertain

  • No pharmacokinetic study of this analogue has ever been published in any species. Every duration and potency claim is user report plus chemical inference.
  • The commonly quoted 'three to ten times more potent than Semax' figure has no published source I could find. Treat it as folklore.
  • Nobody has confirmed the acetylated-amidated form binds the same brain site as Semax, or with what affinity.
  • Whether N-terminal acetylation of the methionine alters activity at the target - as opposed to only altering stability - is unstudied.
  • The 8-12 hour duration figure is entirely from user reports. There is no measurement behind it.
  • Purity, identity and completeness of capping vary between suppliers and there is no reference standard to check against.
  • The earlier onset of emotional blunting compared to plain Semax is a consistent anecdotal pattern with no mechanistic study behind it.
  • The molecular weight of 855.0 Da in the Core record is consistent with acetylation plus amidation of the 813.9 Da parent, but I did not verify it against a published characterisation.

Papers