what is Semax?

In the 1980s, researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences began investigating fragments of adrenocorticotropic hormone (ACTH) for their effects on cognition and neuroprotection. The key insight was that ACTH(4-10) -- a seven-amino-acid fragment -- retained the cognitive-enhancing properties of full ACTH without the hormonal side effects (cortisol release, adrenal stimulation).

The problem was stability. The naked ACTH(4-10) fragment was rapidly degraded by peptidases in the blood and nasal mucosa. To solve this, the team added a Pro-Gly-Pro (PGP) tripeptide to the C-terminus. This extension increased resistance to enzymatic degradation without altering the core pharmacological activity, creating the molecule now known as Semax.

Adrenocorticotropic hormone (ACTH) is a 39-amino-acid hormone produced by the anterior pituitary. Its primary endocrine function is stimulating the adrenal cortex to produce cortisol via the MC2R receptor. But decades of research showed that ACTH fragments -- particularly positions 4 through 10 -- had independent effects on the central nervous system including improved attention, memory consolidation, and neuroprotection.

The critical discovery was that these cognitive effects did not require MC2R activation. The ACTH(4-10) fragment has essentially zero affinity for MC2R, meaning it cannot trigger cortisol release or interfere with the hypothalamic-pituitary-adrenal (HPA) axis. Instead, it appears to work through neurotrophic factor upregulation (particularly BDNF and NGF) and monoamine neurotransmitter modulation.

The ACTH(4-7) tetrapeptide -- Met-Glu-His-Phe -- is considered the minimal active core, with the remaining residues and the Pro-Gly-Pro tail contributing to stability rather than primary receptor binding. Semax-driven BDNF and NGF upregulation in hippocampal tissue has been documented in multiple rodent studies and partially corroborated by serum BDNF measurements in small Russian human trials, particularly in stroke and brain injury populations. This neurotrophic mechanism distinguishes Semax from stimulant-class nootropics and underlies the neuroprotective rationale for its approved clinical indications.

Semax is approved as a prescription medication in Russia and Ukraine for several indications: treatment of ischemic stroke (both acute and recovery phases), dyscirculatory encephalopathy (chronic cerebrovascular insufficiency), and optic nerve atrophy. It is available as a 0.1% and 1% intranasal solution.

This regulatory status sets Semax apart from most peptides discussed in the nootropic community. It has gone through formal clinical trials (albeit under the Russian regulatory system, which differs from FDA/EMA standards), received marketing authorization, and has been prescribed to patients for over two decades. The evidence base is not perfect by Western standards, but it is substantially larger than what exists for most research peptides.

Selank is Semax's sister peptide, developed at the same institute. While Semax is derived from ACTH(4-10), Selank is derived from tuftsin (Thr-Lys-Pro-Arg), an endogenous immunomodulatory tetrapeptide, with the same Pro-Gly-Pro extension. Selank's primary effects are anxiolytic (anti-anxiety) rather than nootropic, working through GABA modulation rather than BDNF upregulation.

community modifications and related peptides

N-Acetyl Semax Amidate (NASA) is a community modification of Semax with an acetyl group on the N-terminus and an amide group on the C-terminus. These modifications are intended to further increase metabolic stability and potentially enhance potency. NASA has no clinical data -- it is a gray-market modification that has not been studied in any formal setting.

Cerebrolysin is a different class of neuropeptide product entirely -- a standardized mixture of low-molecular-weight peptides derived from porcine brain tissue. It is also approved in Russia (and several other countries) for stroke and dementia, but its mechanism is broader and less precisely characterized than Semax's.