Semax

ACTH is a hormone the body produces naturally, and a small piece of it forms the seven-amino-acid backbone of Semax, assembled in a lab. First developed in Russia to aid recovery after stroke, it has been studied in both animals and people, mostly given as nasal drops so it can reach the brain quickly, for its impact on memory, attention, and healing after damage to the brain.

What it is

Semax comes from fragment 4 through 10 of ACTH, a natural hormone, but the finished peptide is described in the research literature as working differently from that parent hormone, acting instead on brain chemical systems tied to learning and memory.

Because it is given through the nose, researchers describe Semax as reaching the brain by traveling along the olfactory and trigeminal nerves near the nasal passages, a route that can carry a peptide toward brain tissue without needing to cross into the bloodstream first. Reported research links the peptide to a quick rise in a nerve-growth protein called BDNF.

How it is studied

Semax has been studied in human trials in stroke patients receiving standard rehabilitation care, in healthy volunteers using brain imaging to look at neural activity after a single treatment, and in rats using genetic techniques to see which genes change after a simulated stroke.

What studies report

In 110 patients recovering from an ischemic stroke, treatment alongside standard rehabilitation was linked to higher levels of the nerve-growth protein BDNF, which correlated with faster recovery of brain function, especially movement-related symptoms. [1]
In 24 healthy middle-aged adults, a single treatment increased activity in a brain network linked to internal thought and self-referential processing, called the default mode network, compared with placebo, as measured by brain imaging. [2]
In rats given a treatment that simulates a stroke, Semax changed the activity of 96 genes tied to the immune and blood-vessel systems, a pattern the researchers link to effects on inflammation and blood flow during the injury. [3]

What is not known

The clinical study on stroke recovery combined Semax with standard rehabilitation rather than testing it alone, making it harder to separate the peptide's specific contribution from the effect of rehabilitation itself. Most of Semax's human research has been conducted in Russia, and independent replication in other research settings is limited in the sources reviewed for this entry.

Regulatory status

The FDA has not approved Semax. Russia originally developed it for use as a pharmaceutical there, while in most other jurisdictions it stays classified as a research compound, with no equivalent FDA clearance identified in the sources reviewed.