What is Semax?
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro, derived from fragment 4-7 of adrenocorticotropic hormone (ACTH) with a Pro-Gly-Pro extension. It was developed at the Institute of Molecular Biology in Moscow in the 1980s as a neuroprotective and cognitive agent.
Unlike full ACTH (which stimulates cortisol production), Semax’s fragment 4-7 has no activity on the adrenal gland — its effects are exclusively central, acting on the nervous system as a neuromodulator and neuroprotector.
It is approved in Russia under the brand name Semax for treatment of ischemic stroke, traumatic brain injury (TBI), cognitive impairment, and early Alzheimer’s disease.
Mechanism of action
Neurotrophins (BDNF, NGF):
- Semax significantly increases levels of BDNF (Brain-Derived Neurotrophic Factor) and NGF (Nerve Growth Factor) in the hippocampus and cerebral cortex.
- BDNF is fundamental for synaptic plasticity, learning and memory, and protection of neurons under stress.
- BDNF levels decline in depression, Alzheimer’s, and aging; Semax restores them.
CREB and plasticity:
- Activates the transcription factor CREB (cAMP response element-binding protein), which regulates the expression of genes related to long-term memory and synaptic formation.
Dopaminergic system:
- Modulates dopaminergic transmission in the nucleus accumbens, related to motivation and concentration.
Neuroprotection:
- In cerebral ischemia models, Semax reduces the infarct area and improves functional recovery — the basis for its approved use in stroke.
Reported effects in research
- Improvement in attention, concentration, and working memory.
- Reduction of anxiety and anxiolytic effects at moderate doses.
- Antidepressant effects (via BDNF and dopamine).
- Neuroprotection in hypoxia and trauma models.
- Potential in ADHD (modulates dopamine without the amphetamine mechanism).
Semax intranasal vs. injectable
The intranasal route is the most common in research due to convenience and good absorption through the olfactory mucosa to the olfactory bulb and limbic system. The subcutaneous route is also documented.
Safety profile
Decades of clinical use in Russia show excellent tolerability. Reported adverse effects: mild nasal irritation (intranasal use), occasional headache. No effects on cortisol, blood pressure, or hormonal function are reported.
Approved in Russia; investigational in the U.S. For research use only. Clinical data come primarily from Russian literature. Consult a physician specialized in neuro-optimization before use.
Reported protocol (research reference)
| Vial sizes | 5 mg, 10 mg |
|---|---|
| Reported dose | Russian approved protocol: 200–2,600 mcg intranasal or SC per day for 7–14 days. Reported nootropic use: 100–600 mcg intranasal 1–2x/day. Reference values only. |
| Half-life | ~1–2 hours in plasma. Effects on BDNF persist longer. |
| FDA status | Not FDA approved |