Semax

Semax (Russian: Семакс, an abbreviation of "seven amino acids" - семь аминокислот) is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It is a modified analog of the ACTH(4-10) fragment of adrenocorticotropic hormone, engineered to preserve the central nervous system activity while lacking the hormonal cortisol-stimulating activity of the parent hormone. It was developed at the Institute of Molecular Genetics of the Russian Academy of Sciences in Moscow. It was approved in the Russian Federation in 1995 for acute ischemic stroke and other neurological indications and is sold as Semax intranasal spray.

The molecule first appeared in the scientific literature in 1991. The development team led by N.F. Myasoedov and I.P. Ashmarin (the same Russian institute that produced Selank) was working on a class of regulatory peptides derived from natural mammalian hormones. The Pro-Gly-Pro C-terminal stabilization is shared with Selank and protects the peptide from rapid enzymatic degradation in the nasal mucosa and CNS.

The Russian-approved formulations include 0.1 percent intranasal spray (for routine nootropic and anxiety indications) and 1 percent intranasal spray (for acute neurological events like stroke). The dosing varies by indication, ranging from a few drops daily for cognitive enhancement to substantially higher doses for acute stroke management.

Outside Russia, Semax has not received approval from any major regulator. There is no FDA approval, no EMA approval, no MHRA approval. The compound is sold widely by online research-chemical vendors with "for laboratory use only" labeling. Some users acquire the Russian-approved pharmaceutical product through international channels.

The Russian Clinical Evidence

The Semax evidence base is concentrated in Russian-language publications. The major trial programs documented in available English-language sources include:

Acute ischemic stroke trials. Russian neurology trials in the 1990s and early 2000s established Semax as adjunctive therapy in acute ischemic stroke. Reported benefits include reduced neurological deficit, improved functional recovery, and shorter rehabilitation time. The 1 percent intranasal formulation was approved in 1995 specifically for this indication.

Cognitive impairment and post-stroke rehabilitation. Open-label and small randomized trials in patients with vascular cognitive impairment, post-stroke cognitive deficit, and mild cognitive impairment reported improvements in memory, attention, and executive function. Methodology in many of these trials does not meet Western randomized-trial standards.

Pediatric ADHD. Semax has been studied in Russian pediatric populations as a treatment for attention deficit hyperactivity disorder. Reported effects include improved attention, reduced impulsivity, and better academic performance. The pediatric indication is less commonly cited in Western reviews but represents a substantial part of Russian clinical use.

Anxiety and depression. Smaller trials have reported anxiolytic and antidepressant effects, often in combination with the cognitive benefits. The clinical positioning in Russia overlaps somewhat with Selank, though Semax is typically described as more activating and cognitively focused.

A PubMed search for "Semax" returns approximately 150 results, the majority of which are mechanistic studies in animal models published by Russian groups in journals like Doklady Biological Sciences or Bulletin of Experimental Biology and Medicine. The translation gap between Russian neurology trials and Western clinical evidence standards is real and is the central limitation of the Semax evidence base for Western reviewers.

A 2025 review by the original Russian development group summarized the cumulative transcriptomic and clinical work, including effects on brain cell gene expression patterns and ongoing clinical use as a neuroprotective and nootropic drug in Russian medical practice.

Semax's mechanism is partially characterized and not fully translated to Western neuropharmacological terms. The published Russian literature documents several effects.

BDNF upregulation. Brain-derived neurotrophic factor is the most consistently reported downstream effect of Semax administration. BDNF supports neuronal survival, synaptic plasticity, and learning processes. Animal studies report dose-dependent BDNF increases in hippocampus and cortex within hours of intranasal administration.

Dopaminergic sensitization. Semax modulates dopamine signaling in regions associated with attention and motivation. The effect appears to be sensitization (increased responsiveness to existing dopamine) rather than direct dopamine release. The clinical correlate is improved focus and motivation without the receptor downregulation associated with chronic dopaminergic stimulation.

Enkephalinase inhibition. Like Selank, Semax inhibits enkephalin degradation. The result is increased availability of endogenous opioid signaling in pain and mood regulation pathways. This may contribute to the antidepressant and analgesic effects reported in some Russian trials.

Melanocortin receptor modulation. As an ACTH-derived peptide, Semax has weak activity at central melanocortin receptors (MC3R, MC4R, MC5R) that may contribute to neuroprotection and modulation of arousal pathways.

Neuroprotection in ischemia. The neuroprotective effects in acute ischemic stroke models appear to involve reduced excitotoxicity, anti-inflammatory effects in damaged brain tissue, and support for endogenous repair mechanisms. The acute stroke approval is based on these mechanistic claims combined with clinical trial evidence in Russian stroke units.

Regulatory status

Russia. Semax has been approved by the Russian Federation Ministry of Health since 1995. The major approved indications are acute ischemic stroke (1 percent intranasal), cognitive impairment, transient ischemic attack, post-stroke rehabilitation, and pediatric ADHD (lower-concentration formulations). The compound is dispensed as a prescription medication in Russian pharmacies.

United States. Semax has no FDA approval. It is not on the FDA Category 2 bulks list as of May 2026, which is unusual for a non-approved peptide and may reflect the smaller commercial footprint compared with more widely marketed peptides. The regulatory position is informal: widely sold by online research-chemical vendors, occasionally available through US compounding pharmacies in lower-volume settings, with "for laboratory use only" labeling that the resale ecosystem ignores.

EU and UK. No EMA or MHRA authorization. The compound has not been formally evaluated by major Western regulators despite the Russian approval history dating to 1995.

WADA status. Semax is not currently on the WADA Prohibited List. The compound has not been positioned as a performance-enhancing substance, though the BDNF and dopaminergic effects could in principle be relevant to certain sport categories. The cognitive enhancement effect alone is not typically grounds for prohibition unless tied to performance categories.

Dosing protocols and literature-reported ranges are documented in the approved label or trial publications referenced above.

The Russian post-marketing safety record extends nearly 30 years. The compound has been used in pediatric populations for ADHD and in geriatric populations for cognitive impairment, which provides safety coverage across a wide age range that few peptides match.

Mild headache in a small percentage of subjects, typically transient.

Local nasal irritation with the intranasal formulation. Generally mild and resolves with continued use or briefly switching to alternate nostrils.

Increased blood pressure has been reported in some cases at higher doses (the 1 percent stroke formulation). The MC4R-related autonomic effects may be relevant. Patients with uncontrolled hypertension should approach Semax cautiously.

Stimulation or restlessness. Some users report transient activation, particularly when dosing later in the day. Morning dosing is typical for cognitive enhancement use.

No documented dependence or withdrawal phenomena with chronic dosing or discontinuation.

No documented serious systemic toxicity in the cumulative Russian post-marketing dataset.

The published Western safety data is limited. The compound has not undergone Phase 3 safety trials at the size or duration that Western regulators require for approval. Long-term safety data in non-Russian populations is essentially absent from peer-reviewed Western literature.

The most natural comparison is between Semax and Selank. Both peptides were developed at the same Russian institute. Both have the same C-terminal Pro-Gly-Pro stabilization. Both are administered intranasally. The clinical positioning differs: Semax is the nootropic and neuroprotective compound (BDNF upregulation, dopaminergic sensitization, ischemia protection). Selank is the anxiolytic (GABA modulation without sedation). They are often combined in adult nootropic protocols and are commonly referred to as the "Russian nootropic stack."

Cerebrolysin is a porcine brain-derived peptide preparation used in Russian and German neurology for cognitive impairment and stroke. The two compounds occupy similar clinical positions but differ structurally (Cerebrolysin is a multi-peptide preparation rather than a single defined molecule).

Modafinil and racetams (piracetam, aniracetam, oxiracetam) are non-peptide nootropics with different mechanisms (dopaminergic modulation, AMPA modulation). Semax differs in being a peptide with documented neuroprotective effects in acute ischemic stroke, which racetams do not match.

BDNF-targeting compounds like ketamine (in psychiatric use) and exercise (the strongest endogenous BDNF stimulus) are mechanistically similar to Semax in producing BDNF upregulation. Whether Semax adds meaningful BDNF effect beyond what regular aerobic exercise produces has not been formally tested.