Two Russian Nootropics, Two Distinct Mechanisms
Selank and Semax are both synthetic heptapeptides developed at the Institute of Molecular Genetics in Moscow. Both are administered intranasally and both modulate brain-derived neurotrophic factor (BDNF). But their clinical effects are dramatically different.
Semax is derived from ACTH (adrenocorticotropic hormone) fragments 4-10 and primarily enhances cognitive function, focus, and dopaminergic tone. Selank is derived from the immunomodulatory peptide tuftsin and primarily reduces anxiety through GABAergic modulation.
Semax: The Cognitive Enhancer
Semax (Met-Glu-His-Phe-Pro-Gly-Pro) upregulates BDNF expression by 300-400% in animal models. It enhances dopamine and serotonin signaling in the prefrontal cortex, improving working memory, attention, and executive function.
The N-Acetyl Semax Amidate (NASA) variant adds acetyl and amide groups for improved stability and blood-brain barrier penetration. Standard intranasal dose: 200-600 mcg per nostril, 1-2 times daily.
Clinical applications in Russia: post-stroke cognitive recovery, ADHD-like executive dysfunction, and optic nerve disease. Semax is approved as a prescription medication in Russia and Ukraine.
Selank: The Anxiolytic
Selank (Thr-Lys-Pro-Arg-Pro-Gly-Pro) modulates GABA-A receptor sensitivity, producing anxiolytic effects comparable to benzodiazepines without sedation, cognitive impairment, or addiction potential.
It also modulates enkephalin expression (endogenous opioid peptides) and stabilizes IL-6, providing both anti-anxiety and immune-modulatory benefits. Standard intranasal dose: 250-500 mcg per nostril, 1-3 times daily.
Clinical applications in Russia: generalized anxiety disorder, adaptive stress response, and immune support during chronic stress.
Head-to-Head Comparison
Choose Semax if your primary goal is cognitive enhancement: better focus, sharper memory, and improved productivity. It is stimulatory and best used during work hours.
Choose Selank if your primary goal is anxiety reduction: calmer baseline, better stress resilience, and improved sleep quality. It is calming without sedation.
Some biohackers use both: Semax in the morning for focus, Selank in the evening for anxiety reduction. This is a reasonable approach given their complementary mechanisms, but has not been formally studied in combination.
Intranasal Administration
Both peptides achieve 10-30% bioavailability via the intranasal route, which is dramatically better than oral (destroyed by GI proteases) and comparable to SubQ for brain-targeted effects because intranasal delivery partially bypasses the blood-brain barrier via olfactory neurons.
Use a metered-dose nasal spray bottle calibrated to deliver consistent volumes. Reconstitute with sterile saline (NOT bacteriostatic water, which burns nasal mucosa). Shelf life is limited — use within 10-14 days refrigerated.
⚕️ Medical Disclaimer: This article is for educational purposes only. Consult a qualified healthcare provider before using any peptide.