Semax vs Selank: Nootropic Peptide Comparison

Semax is a synthetic analogue of the ACTH(4-10) fragment with a C-terminal Pro-Gly-Pro extension for enhanced stability. It was developed at the Russian Institute of Molecular Genetics in the 1980s and approved in Russia as an intranasal drug for cognitive deficits and cerebrovascular conditions. It is studied primarily for neuroprotective and nootropic properties.

Selank is a synthetic analogue of tuftsin (an endogenous immunopeptide) with a stabilizing C-terminal tripeptide sequence Pro-Gly-Pro. Developed at the same institute as Semax, it was approved in Russia as an anxiolytic. It is studied for anxiety regulation, memory enhancement, and immunomodulatory properties.

Semax increases BDNF (Brain-Derived Neurotrophic Factor), NGF, and TrkB levels in the brain, supporting neuroplasticity and neurogenesis. It also modulates monoaminergic signaling (dopamine, serotonin). Selank acts primarily through GABAergic system regulation, enkephalin enhancement, and serotonin modulation. It also functions as an immunomodulator through the IL-6 and cytokine pathway.

Russian clinical studies have evaluated Semax in cerebrovascular events, cognitive dysfunction, optic neuropathy, and ADHD. A study in ischemic stroke patients showed improved neurological recovery. However, most studies are published in Russian journals and require independent Western replication.

Russian clinical trials showed anxiolytic action comparable to low-dose benzodiazepines but without sedation or dependence risk. Studies in generalized anxiety disorder (GAD) report improvement on Hamilton scales, while research data shows immunomodulatory effects in hepatitis C patients.

Both are administered intranasally in Russian clinical protocols — a method that allows blood-brain barrier bypass. Semax is available in 0.1% and 1% (N-Acetyl-Semax-Amidate) concentrations, while Selank at 0.15%. Dosing regimens typically include 200–600 mcg/day for Semax and 250–500 mcg/day for Selank.

Both are reported as well-tolerated in available clinical data, with no significant adverse events. No addictive potential or tolerance is reported. However, Western clinical data (RCTs in non-Russian populations) is virtually nonexistent, limiting the generalizability of findings.

Researchers focusing on neuroprotection, neurogenesis, and BDNF-dependent plasticity tend toward Semax. Researchers interested in anxiolytic action without sedation, GABAergic regulation, or immunomodulation tend toward Selank. The combination (Semax + Selank) exists as a research protocol but has not been systematically studied.