What it is
Semax is a synthetic analog of adrenocorticotropic hormone (ACTH), a natural hormone involved in the body's stress response. It is studied for neuroprotective, cognitive-enhancing, and mildly anxiolytic (anxiety-reducing) effects, and it was developed in Russia, where it has seen extensive clinical use.
In the PeptidesAI encyclopedia it is categorized under cognitive, alongside selank and PT-141, and it shares its Russian development history and limited Western clinical record with selank in particular.
How it's thought to work
Semax is studied for modulating the expression of BDNF and NGF, two proteins that support the growth and survival of neurons, and for enhancing serotonergic and dopaminergic neurotransmission, the signaling systems that use serotonin and dopamine. Research describes these together as contributing to neuroprotective effects through multiple pathways rather than through a single mechanism. Because BDNF and NGF support neuron growth and survival, compounds studied for modulating them, like semax, are often discussed in the context of brain health and recovery from injury such as stroke.
What the research says
Semax is approved in Russia for cognitive enhancement and for stroke recovery. Clinical data from Western countries is limited, so most of the formal approval and clinical use is specific to the Russian regulatory and medical context.
Reported side effects
Semax is generally described as well-tolerated. Rare reports describe irritability or overstimulation, and no serious safety signals are described in the available material.
Reconstitution
Semax is supplied as a lyophilized (freeze-dried) powder and is typically reconstituted with bacteriostatic (BAC) water before use. It commonly comes in 5 mg and 10 mg vials. The amount of peptide in the vial is fixed; the water added only changes how concentrated the solution is.
Worked example. A 5 mg vial is 5,000 mcg. Reconstituted with 1 mL of BAC water, that works out to 5,000 mcg ÷ 1 mL = 5,000 mcg/mL. On a U-100 insulin syringe, where each unit is 0.01 mL, each unit holds 5,000 × 0.01 = 50 mcg. Use the peptide reconstitution calculator to work out the concentration and units for any vial size and water volume.
Important notes
Semax is approved in Russia but is not FDA-approved, so its regulatory status in the United States differs from where it has an established record of clinical use. As with selank, the difference between Russian approval and the absence of FDA review is an important part of understanding semax's overall regulatory picture.
Frequently asked questions
These questions cover the same ground as the sections above, in a shorter format.
What is Semax?
A synthetic analog of ACTH studied for neuroprotective, cognitive-enhancing, and mildly anxiolytic effects, developed in Russia.
How is Semax thought to work?
It is studied for modulating BDNF and NGF expression and enhancing serotonergic and dopaminergic neurotransmission, contributing to neuroprotective effects.
What does the research on Semax say?
It is approved in Russia for cognitive enhancement and stroke recovery; clinical data from Western countries is limited.
What are the reported side effects of Semax?
Generally well-tolerated, with rare reports of irritability or overstimulation.
How much is one unit from a 5 mg Semax vial?
With 1 mL of BAC water, a 5 mg vial is 5,000 mcg/mL, so one unit on a U-100 syringe (0.01 mL) holds 50 mcg.
The full entry, plus the calculator
The PeptidesAI app has the complete encyclopedia entry for Semax — one of 70 compounds covered — plus the reconstitution calculator, a dose log and reminders. Free to download on iPhone.
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