Summary
Semax is a synthetic seven-amino-acid peptide built from a fragment of ACTH, the adrenocorticotropic hormone, with a three-amino-acid tail added to slow its breakdown. It was developed in Russia, where it is used clinically in stroke care; the clinical studies below were run there. It is not an approved medicine in the UK, US or Australia.
What it targets
The fragment Semax derives from is the part of ACTH associated with effects on the brain rather than on the adrenal glands. A genome-wide study in rats after an induced stroke found that Semax mainly altered immune-system genes, which made up over half the affected genes by 24 hours, along with a smaller set of genes involved in blood vessel formation; the authors propose those as the route to the neuroprotective effects reported elsewhere. In mice with spinal cord injury, Semax improved movement scores and reduced a lysosome-related form of cell death, with the mu opioid receptor identified as a target. In artificial membrane systems it interfered with copper-driven aggregation of amyloid beta. The human evidence linked here is a Russian study in 110 people recovering from stroke, in which those given Semax alongside rehabilitation had higher plasma BDNF and better daily-living scores; it compares groups rather than randomising against placebo.
Clinical Research
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