N-Acetyl Semax Amidate vs Semax
Doubly modified ACTH(4-7) analogue heptapeptide with potent nootropic, neuroprotective, and neurotrophic properties acting through BDNF/NGF upregulation and transcriptome-level modulation of inflammatory and neurotransmitter gene networks
A brain-boosting peptide that supercharges your cognitive function by ramping up BDNF—the protein your neurons need to grow, connect, and stay sharp—all delivered through a simple nasal spray.
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
N-Acetyl Semax Amidate
300–600 mcg/day
Semax
500–900 mcg/day
Frequency
N-Acetyl Semax Amidate
Once daily
Semax
Once daily
Administration
N-Acetyl Semax Amidate
Intranasal spray
Semax
Intranasal spray
Cycle length
N-Acetyl Semax Amidate
8-12 weeks
Semax
4-6 weeks
Onset speed
N-Acetyl Semax Amidate
Rapid (hours to days)
Semax
Rapid (hours to days)
Evidence level
N-Acetyl Semax Amidate
Moderate human trials (Phase 1-2)
Semax
Moderate human trials (Phase 1-2)
Benefit ratings
Brain Protection
Memory & Learning
Focus & Attention
Cognitive Enhancement
Neuroprotection
Mental Energy
Compound specifications
N-Acetyl Semax Amidate
Molecular formula
C39H54N10O10S
Molecular weight
855.0 g/mol
Half-life
Extended compared to native Semax; parent Semax has a plasma half-life of minutes, but pharmacological effects persist for hours due to intracellular signaling cascade initiation. N-Acetyl Semax Amidate achieves significantly longer effective duration
Bioavailability
Enhanced intranasal and subcutaneous bioavailability compared to native Semax; dual terminal modifications prevent enzymatic degradation from both ends
CAS number
Not assigned (N-Acetyl Semax Amidate); 80714-61-0 (parent Semax)
Semax
Molecular formula
C37H51N9O10S
Molecular weight
813.9 g/mol
Half-life
Several minutes to hours (intranasal effects persist longer)
Bioavailability
High via intranasal route (directly reaches brain)
CAS number
80714-61-0
Dosing compared
N-Acetyl Semax Amidate
Intranasal
200-300 mcg/day
Divided 2-3 times daily · 2-4 weeks
Lower cognitive-use range with the 0.1% intranasal solution; Russian clinical protocols [6].
300-600 mcg/day
Divided 2-3 times daily · 2-4 weeks per course
Daily intranasal range used for cognitive enhancement with 0.1% Semax in Russian clinical practice; Semax upregulates BDNF/NGF [1][6].
Semax
Intranasal
250-500 mcg/day
Once or twice daily · 1-2 weeks
Cognitive/nootropic practice with the 0.1% solution; downstream BDNF/NGF effects persist 12-24 h so dosing is once to twice daily [1][2].
500-900 mcg/day
Divided 2-3 times daily · 3-4 weeks
Mid-range nootropic practice dose; upregulates hippocampal BDNF/TrkB in animal models [1][2][3].
Best suited for
N-Acetyl Semax Amidate
Cognitive enhancement through BDNF and NGF-mediated neuroplasticity
N-Acetyl Semax Amidate is particularly well-suited for individuals focused on cognitive enhancement through bdnf and ngf-mediated neuroplasticity. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Neuroprotection during and after cerebral ischemic events or brain injury
N-Acetyl Semax Amidate is particularly well-suited for individuals focused on neuroprotection during and after cerebral ischemic events or brain injury. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Nootropic stacking for enhanced learning, memory, and cognitive processing speed
N-Acetyl Semax Amidate is particularly well-suited for individuals focused on nootropic stacking for enhanced learning, memory, and cognitive processing speed. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Attention and focus improvement for cognitively demanding tasks
N-Acetyl Semax Amidate is particularly well-suited for individuals focused on attention and focus improvement for cognitively demanding tasks. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach.
Semax
Students and Knowledge Workers
If your day revolves around learning, studying, or processing complex information, Semax can be a game-changer. It enhances memory consolidation and recall while improving your ability to focus for extended periods—perfect for exam prep or demanding projects [6][12].
Those Seeking Mental Clarity
Brain fog? Semax works by boosting BDNF—the protein that helps neurons communicate effectively. [1][2] Users often report feeling like the 'mental static' clears away, leaving sharper, more efficient thinking in its place.
Neuroprotection Seekers
Beyond immediate cognitive benefits, Semax offers protective effects for your brain cells. [9] It acts as an antioxidant (especially against copper toxicity) [4][8] and supports neuronal health—valuable for anyone concerned about long-term brain wellness.
Recovery Support (Under Medical Supervision)
In Russia, Semax is approved for helping stroke patients and those with traumatic brain injuries recover cognitive function. [6] While not FDA-approved for this use elsewhere, the research shows meaningful neuroprotective and neurorestorative properties [7][9].
Side effects
N-Acetyl Semax Amidate
Common
- Nasal irritation
- Headache
- Mental overstimulation or restlessness
- Sleep difficulty
- Appetite changes
Uncommon
- Hair darkening
Serious
- Allergic reaction
Semax
Common
- Nasal irritation
- Mild headache
- Increased alertness
Uncommon
- Temporary blood pressure increase
- Dizziness
Serious
- Allergic reaction
Safety & evidence
N-Acetyl Semax Amidate
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
N-Acetyl Semax Amidate shows excellent safety tolerability in Russian clinical studies with no serious adverse events reported at therapeutic doses. The amidate modification significantly enhances CNS penetration and metabolic stability compared to parent Semax, reducing dosing frequency. Side effects are primarily mild nasal irritation, transient headaches during initiation, and rare increases in dopaminergic tone manifesting as restlessness or insomnia at high doses, easily managed through dose adjustment.
Contraindications
- Known hypersensitivity to Semax, ACTH fragments, or any formulation component
- Pregnancy and breastfeeding — insufficient safety data in these populations
- Active seizure disorders — neurostimulatory effects may lower seizure threshold in susceptible individuals
- Acute psychotic episodes — dopaminergic and neurostimulatory effects may exacerbate symptoms
Semax
Evidence level
Moderate human trials (Phase 1-2)
FDA status
Research compound
Safety overview
Semax has been used clinically in Russia for over 25 years with an excellent safety profile. [7][12] It's approved there for treating stroke, cognitive impairment, and optic nerve diseases. [6] Studies consistently show minimal side effects, mostly limited to mild nasal irritation when using the spray form. [6][9] Unlike stimulants, Semax doesn't appear to cause tolerance, dependence, or withdrawal symptoms even with extended use.
Contraindications
- Pregnancy or planning to become pregnant
- Currently breastfeeding
- History of seizures or epilepsy
- Known allergy to ACTH-related peptides
- Uncontrolled hypertension
Which is right for you?
Choose N-Acetyl Semax Amidate if...
- Cognitive enhancement through BDNF and NGF-mediated neuroplasticity
- Neuroprotection during and after cerebral ischemic events or brain injury
- Nootropic stacking for enhanced learning, memory, and cognitive processing speed
- Attention and focus improvement for cognitively demanding tasks
Choose Semax if...
- Cognitive enhancement
- Memory improvement
- Focus and concentration
- Neuroprotection