Semax

Semax (Met-Glu-His-Phe-Pro-Gly-Pro) is a synthetic heptapeptide analogue of ACTH(4-10), the N-terminal fragment of adrenocorticotropic hormone, with an added C-terminal Pro-Gly-Pro tripeptide that dramatically extends its biological half-life from minutes to over 20 hours of measurable CNS effect. It was developed at the Russian Academy of Sciences and is registered in Russia as a prescription nootropic and neuroprotective agent.

The precise mechanism of action has not been fully elucidated and is likely multi-target. Semax has been shown to upregulate brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the hippocampus, promoting synaptic plasticity, dendritic arborization, and long-term potentiation — mechanisms directly underpinning memory formation and cognitive resilience. It also modulates melanocortin receptor signaling (MC4R/MC5R) and inhibits enkephalinase enzymes (neprilysin), prolonging the half-life of endogenous enkephalins — opioid peptides involved in mood regulation, pain modulation, and neuroprotection.

Additional mechanisms identified in preclinical research include: reduction of neuroinflammation via suppression of pro-inflammatory cytokines (IL-6, TNF-α); stabilization of the blood-brain barrier under ischemic stress; enhancement of cerebral blood flow through nitric oxide-mediated vasodilation; and modulation of dopamine, serotonin, and norepinephrine metabolism. The C-terminal Pro-Gly-Pro motif not only confers metabolic stability but may independently contribute to neuroprotective effects through its own biological activity.

Semax was first described in the scientific literature in 1991 by researchers at the Russian Academy of Sciences and has since been extensively studied in over 300 publications, predominantly from Russian and Eastern European research institutions. It is listed on the Russian List of Vital & Essential Drugs and is approved for clinical use in stroke rehabilitation, transient ischemic attack, cognitive disorders, optic nerve atrophy, and as an immunomodulator.

The peptide has generated significant interest in Western biohacking and nootropic communities over the past decade as a cognitive-enhancement research tool. Its ability to elevate BDNF — the same neurotrophin targeted by exercise, ketamine, and classical antidepressants — positions it as a mechanistically distinct nootropic with a plausible neuroplasticity-driven basis for its reported cognitive effects. However, independent Western clinical trials have not been completed as of 2026, and the existing evidence base is dominated by Russian-language publications.

Store lyophilized Semax powder at -20°C in a light-protected, desiccated environment. The peptide is relatively stable — the C-terminal Pro-Gly-Pro modification provides significant resistance to aminopeptidase degradation. Long-term stability exceeds 18 months when properly stored.

For intranasal research protocols, Semax is typically reconstituted not in BAC water but in sterile saline (0.9% NaCl) at a concentration of 1% (10 mg/ml) and stored in a sterile nasal spray bottle at 2–8°C for up to 30 days. The intranasal route achieves high CNS bioavailability while largely bypassing first-pass metabolism. For subcutaneous protocols, reconstitute with standard BAC water and store at 2–8°C, using within 21 days. Avoid freezing reconstituted solutions.