What Semax is
Semax is a heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. The first four residues correspond to ACTH(4-7); the terminal Pro-Gly-Pro tripeptide was added by Myasoedov's group to resist peptidase degradation and extend circulating half-life beyond what the bare ACTH fragment provides. The compound carries no adrenal hormonal activity and does not stimulate cortisol release, because it lacks the C-terminal sequences required to activate the adrenal ACTH receptor.
Semax is registered in Russia and Ukraine as a prescription nasal spray under several clinical indications, including acute ischemic stroke, optic nerve disease, and attention and memory disorders. No Western regulatory body (FDA or EMA) has approved it for any indication. Outside of Russia and Ukraine it is unregulated research material, typically supplied as a lyophilized powder or a 1% nasal solution. View the Semax compound listing for current supply details.
Mechanism of action
Semax is classified as a melanocortin peptide analogue. Research shows it interacts with melanocortin receptor subtypes, including MC4R, where it partially antagonizes the cAMP-inducing effect of alpha-melanocyte-stimulating hormone without itself producing cAMP changes. The ACTH(4-7) core also modulates monoaminergic neurotransmission through pathways shared with other melanocortin fragments.
Two downstream effects are most consistently documented. On the neurotrophin side, Shadrina and colleagues tracked NGF and BDNF gene expression in rat hippocampus, frontal cortex, and retina after Semax administration. BDNF mRNA in the hippocampus rose within 90 minutes and remained elevated for at least 24 hours; the expression dynamics differed by brain region, with the frontal cortex showing changes on a shorter timescale than the hippocampus (Shadrina et al., J Mol Neurosci, rodent model).
On the monoamine side, Eremin and colleagues measured striatal 5-HIAA (a serotonin metabolite) and dopamine levels in rats. Tissue 5-HIAA in the striatum increased 25% at 2 hours post-dose; extracellular striatal 5-HIAA climbed up to 180% at 1 to 4 hours. Semax pretreatment also amplified D-amphetamine-induced dopamine release and locomotor activity, pointing to a potentiating effect on dopaminergic tone that is not present with Semax alone at the doses tested (Eremin et al., Neurochemical Research, 2006, rodent in vivo).
Semax neuroprotection research
The largest body of Semax research uses rat cerebral ischemia models. Genome-wide transcriptional analysis of rat brains after transient middle cerebral artery occlusion (tMCAO) found that Semax suppressed inflammatory transcripts (IL-1a, IL-1b, IL-6, CCL3, CXCL2) that ischemia-reperfusion normally upregulates, while activating neurotransmitter-related and neurotrophin-related genes. This pattern appears consistently across multiple Russian research groups working independently.
A 2021 proteomics study in the International Journal of Molecular Sciences applied Semax in a rat ischemia-reperfusion model and used two-dimensional gel electrophoresis to map protein expression changes. The authors identified shifts in cytoskeletal, mitochondrial, and oxidative-stress-response proteins consistent with reduced ischemia-induced cell death, and the protein-level results confirmed the transcriptional patterns seen in earlier RNA-Seq work on the same model (Budzinskaya et al., IJMS, 2021, rat model).
In a separate cortical infarct model, 6 days of intranasal Semax decreased lesion volume and improved conditioned avoidance retention compared to untreated controls. The intranasal route matters here: the peptide reaches CNS tissue without gut absorption or hepatic first-pass metabolism, which is why most clinical Semax protocols use nasal spray rather than injection.
Clinical data from Russian stroke trials
Two Russian clinical studies indexed on PubMed carry enough methodological detail to cite directly. The earlier, by Gusev, Skvortsova, Myasoedov and colleagues (1997), enrolled 30 patients with acute hemispheric ischemic stroke receiving Semax plus standard intensive care, compared against 80 matched controls on standard care alone. The authors monitored EEG mapping and somatosensory evoked potentials alongside clinical rating scales. Semax-treated patients showed accelerated regression of focal neurological deficits, particularly motor symptoms, though the study was not placebo-controlled and blinding was not described (Gusev et al., Zh Nevrol Psikhiatr, 1997, n=30 Semax / 80 controls).
The second enrolled 110 post-stroke patients (43 men, 67 women, mean age 58.0 +/- 9.7 years) split into early rehabilitation (89 +/- 9 days post-stroke) and late rehabilitation (214 +/- 22 days) subgroups. Treatment was 6000 mcg/day for 10 days, given in two courses separated by a 20-day interval. Semax-treated patients maintained higher plasma BDNF levels throughout the study period and showed faster improvement on the Barthel Activities of Daily Living index. BDNF levels correlated positively with Barthel score in both rehabilitation timing groups (Miasoedova et al., Zh Nevrol Psikhiatr, n=110 patients).
Neither trial used a double-blind, placebo-controlled design by current ICH guidelines. They provide directional clinical signal in a stroke-specific patient population, not regulatory-quality efficacy evidence.
Cognitive and neural network effects in healthy subjects
A 2018 resting-state fMRI study is the only published human trial in a non-stroke population. Investigators allocated 24 healthy volunteers to 1% intranasal Semax (n=14) or placebo (n=10) and ran fMRI scans at baseline, 5 minutes, and 20 minutes post-dose. The Semax group showed a significantly larger volume of the medial frontal cortex subcomponent of the default mode network at both post-dose time points relative to the placebo group (Sokolov et al., Bull Exp Biol Med, 2018, n=24 healthy volunteers).
The study establishes that intranasal Semax produces measurable changes in resting neural network architecture within minutes of dosing. It does not link those changes to behavioral cognitive outcomes; no memory, attention, or reaction time tasks were part of the protocol. No indexed controlled trial has examined performance endpoints in healthy human subjects.
Storage, handling, and Indonesian research context
Lyophilized Semax stores below -18 C for long-term stability. Reconstituted solutions kept at 2 to 8 C should be used within 14 days to limit degradation. The standard reconstitution procedure and sterile diluent selection are covered in the peptide reconstitution guide. Volume draws from reconstituted solutions can be verified at the dosing calculator.
Semax is water-soluble at physiological pH and does not require acid reconstitution, unlike some hydrophobic peptides. The Pro-Gly-Pro C-terminal extension increases resistance to routine peptidase activity compared to the bare ACTH fragment, but lyophilized peptides still degrade under high-humidity conditions. In Bali and other Indonesian locations where relative humidity regularly exceeds 70%, desiccant storage for the powder form is necessary. Once reconstituted, refrigerator-only storage applies regardless of ambient humidity.
Researchers sometimes ask whether Semax can be usefully grouped with growth hormone secretagogues. It cannot: CJC-1295 and Ipamorelin act through GHRH receptors and GHS-R to drive pulsatile GH release, while Semax acts through melanocortin receptors and neurotrophin pathways. The compounds share no mechanism and no overlap in the published research literature.
Evidence summary and research limitations
The Semax preclinical literature is coherent. Across more than 25 years of rat and mouse work, independent groups have found anti-inflammatory transcriptional effects in ischemia models, BDNF and NGF induction in hippocampal tissue, and monoamine modulation in intact rodents. The mechanistic picture has remained stable since the early 2000s; more recent proteomics and transcriptomics work adds resolution without altering the core findings.
The human literature is thin and almost entirely Russian-language. The two indexed stroke trials show positive directional results but lack placebo controls and adequate blinding. The healthy-volunteer fMRI study is underpowered (n=24) and measures neural network geometry rather than cognitive performance. No Western Phase 2 or Phase 3 trial data appears in ClinicalTrials.gov for any Semax indication as of 2026. Researchers should treat Semax as having a well-characterized preclinical mechanism and limited but directionally consistent early clinical data in stroke rehabilitation, with no controlled evidence for cognitive enhancement in healthy subjects.