Semax is a heptapeptide derived from the ACTH(4-10) sequence, developed at the Institute of Molecular Genetics and classified as a melanocortin-derived neuropeptide nootropic. It is approved in Russia and Ukraine for acute ischemic stroke, cerebrovascular insufficiency, cognitive disorders, and optic nerve disease, and it appears on Russia’s vital and essential drugs list. It is not FDA approved and carries no approval in Europe or other countries, where it remains research only. This lesson reviews a nasal peptide that may be underutilized in the neuroprotective toolkit.

Mechanism of action

Semax acts primarily through the brain-derived neurotrophic factor (BDNF) and TrkB system, with reported increases in BDNF messenger RNA of roughly threefold and TrkB phosphorylation of about 1.6-fold. Studies describe upregulation of nerve growth factor, NT3, TrkA, and TrkC, along with hippocampal calcium dynamics tied to learning and memory. As an ACTH(4-10) fragment, it engages melanocortin receptors, including MC4R for cognitive and nootropic effects, while reducing the endocrine activity full ACTH would carry. At nootropic doses, the transcript notes no HPA axis stimulation.

A separate mechanism is copper chelation. A histidine residue allows Semax to extract copper from the amyloid beta complex, which in vitro work links to reduced amyloid beta-42 toxicity and lower copper-catalyzed reactive oxygen species. In ischemia models, Semax suppressed inflammatory signaling, including several interleukins and chemokines, and downregulated MMP-9 in a way associated with blood-brain barrier integrity. Genome-wide, the immune response was the most affected process.

Clinical evidence and dosing

The strongest human data sit in stroke. A 30-patient acute stroke study used intranasal Semax at 12 mg/day for moderate and 18 mg/day for severe strokes over five to ten days, with reported regression of motor deficits. A 187-patient cerebrovascular insufficiency cohort described stabilization of disease progression. Optic nerve work in 74 patients reported changes in visual acuity, fields, and color vision. Cognitive and nootropic use is described intranasally at 200 to 600 mcg/day for ten to fourteen days. All randomized controlled data come from Russian trials, and the Alzheimer’s and copper-amyloid findings remain in vitro and animal models awaiting human validation.

Key clinical points

• Semax is an ACTH(4-10) analog approved only in Russia and Ukraine; it is research only and not FDA approved in the US.
• Reported mechanisms center on BDNF/TrkB upregulation, melanocortin (MC4R) signaling, anti-inflammatory gene modulation, and copper chelation from amyloid beta.
• Post-stroke neuroprotection and cerebrovascular insufficiency carry the strongest clinical-trial support; optic nerve and glaucoma data are moderate; Alzheimer’s-model data are emerging and in vitro.
• The transcript reports a favorable safety profile with mild nasal irritation and no serious adverse events, while flagging anxiety at higher doses and possible glucose fluctuations to monitor.
• It is framed as an adjunct to standard care, not a replacement, with dosing titrated per patient and intermittent rather than daily use suggested for cognitive support.