Semax vs PE-22-28
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: SEMAX, Heptapeptide SEMAX
Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) developed in Russia in the 1980s as an analog of the ACTH(4-10) fragment, with a Pro-Gly-Pro tail added to resist breakdown. It is researched and used as a neuroprotective and nootropic agent, typically intranasally, and keeps the cognitive and neurotrophic effects of the ACTH fragment without the parent hormone's cortisol-raising activity. It is used clinically and registered in Russia (including for ischemic stroke and cognitive disorders) but is not approved by the FDA or EMA, and Western evidence is limited.
Also: PE22-28, Spadin Analog
PE-22-28 is a seven-amino-acid peptide that blocks a potassium channel in the brain called TREK-1, the same target tied to depression. It is a shortened, more potent and more stable version of spadin, a natural fragment cut from the sortilin propeptide, and it was built to act like a fast antidepressant. All evidence is from rodents. There are no human clinical trials.
Key Comparison Insights
- Both peptides belong to the Cognitive category, suggesting similar primary applications.
- Semax has stronger research evidence (Human Trials) compared to PE-22-28 (Animal Studies).
Detailed Comparison
| Attribute | Semax | PE-22-28 |
|---|---|---|
| Category | Cognitive | Cognitive |
| FDA Status | Not FDA Approved | Not FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | Semax is derived from ACTH(4-10) but, unlike ACTH, does not stimulate the adrenal or cortisol axis; its main documented action is upregulating brain-derived neurotrophic factor (BDNF) and its receptor TrkB, especially in the hippocampus. In rats, a single dose increases BDNF protein and mRNA and raises TrkB phosphorylation, activating growth and survival pathways (such as MAPK/ERK and PI3K/Akt) that support neuron health and plasticity. It also modulates dopamine and serotonin signaling and influences genes tied to the immune and vascular response after brain ischemia. The combined effect in animal models is neuroprotection against insults like reduced blood flow and oxidative stress, plus enhanced learning and memory. The Pro-Gly-Pro extension makes it more stable than the bare ACTH(4-10) sequence, which is partly why it stays active intranasally. | PE-22-28 inhibits TREK-1, a two-pore-domain potassium channel that normally lets potassium leak out of neurons and quiets them down. Block that leak and serotonin-producing neurons in mood-related regions become easier to fire, which is the proposed antidepressant mechanism. This is the same pathway implicated in why TREK-1 knockout mice show a depression-resistant phenotype. Compared to the parent peptide spadin, PE-22-28 binds TREK-1 far more tightly and survives much longer in the body, which is why it was developed. Whether TREK-1 blockade translates into a real antidepressant effect in people remains unproven. |
| Common Dosing | 200-600 mcg intranasal daily 1-3x daily, intranasal | 100-300 mcg intranasal or subcutaneous Once daily |
| Administration | Intranasal spray (most common) | Intranasal or subcutaneous injection |
| Typical Duration | 10-30 days typical | Research protocols vary, often 2-4 weeks |
| Best Time to Take | Morning or early afternoon | Morning |
Possible Side Effects May vary by individual |
|
|
| Research Summary | The mechanistic core is well documented preclinically: Dolotov et al. (2006, Brain Research) showed a single intranasal Semax dose raised hippocampal BDNF protein, TrkB phosphorylation, and BDNF and TrkB mRNA in rats, alongside improved learned behavior. Additional rat work shows neuroprotection and changes in immune- and vascular-related gene expression after experimental stroke. Human clinical use is real but the published trials are mostly Russian-language, small, and frequently non-randomized or open-label: studies in acute ischemic-stroke patients reported faster recovery of neurological function, and a 2018 study reported increased plasma BDNF with improvements on disability and motor scales. These results are promising but methodologically weaker than Western regulatory-grade trials and have not been replicated in large independent Western studies. Honest summary: solid animal mechanistic data and decades of Russian clinical use, but the human cognitive and stroke claims rest on small, mostly non-randomized studies and are not validated by FDA or EMA-grade trials. | The core data come from a single 2017 paper by Djillani and colleagues in Frontiers in Pharmacology, which screened shortened spadin analogs and found PE-22-28 to be the standout: dramatically stronger TREK-1 inhibition, longer in vivo stability, and antidepressant-like behavior in mice using standard tests like the forced swim and novelty-suppressed feeding paradigms. The same line of work reported that short treatment courses increased hippocampal neurogenesis in rodents, which the authors framed as a possible mechanism for faster mood effects than conventional SSRIs. The broader TREK-1 and spadin story traces back to Mazella et al. in 2010, who first described spadin as a natural antidepressant-type TREK-1 blocker. Importantly, every result is preclinical and in animals. There are no completed or published human efficacy or safety trials of PE-22-28, and it is not an approved drug anywhere. Claims that it treats depression, anxiety, or cognitive decline in people go well beyond what the evidence supports. |
Frequently Asked Questions: Semax vs PE-22-28
What is the difference between Semax and PE-22-28?
Semax is a cognitive peptide that semax is a synthetic heptapeptide (met-glu-his-phe-pro-gly-pro) developed in russia in the 1980s as an analog of the acth(4-10) fragment, with a pro-gly-pro tail added to resist breakdown. it is researched and used as a neuroprotective and nootropic agent, typically intranasally, and keeps the cognitive and neurotrophic effects of the acth fragment without the parent hormone's cortisol-raising activity. it is used clinically and registered in russia (including for ischemic stroke and cognitive disorders) but is not approved by the fda or ema, and western evidence is limited. PE-22-28 is a cognitive peptide that pe-22-28 is a seven-amino-acid peptide that blocks a potassium channel in the brain called trek-1, the same target tied to depression. it is a shortened, more potent and more stable version of spadin, a natural fragment cut from the sortilin propeptide, and it was built to act like a fast antidepressant. all evidence is from rodents. there are no human clinical trials. The main differences lie in their mechanisms of action and clinical applications.
Which is better, Semax or PE-22-28?
Neither is universally "better" - the choice depends on your specific goals. Semax is typically used for cognitive purposes, while PE-22-28 is used for cognitive. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can Semax and PE-22-28 be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using Semax and PE-22-28 together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.