Dihexa vs PE-22-28
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: N-hexanoic-Tyr-Ile-(6) aminohexanoic amide
Dihexa (N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) is a small synthetic peptide built from angiotensin IV, engineered at Washington State University to be orally active and to cross into the brain. The pitch is bold: it is studied as a procognitive compound that may rebuild synaptic connections, and lab claims of extreme potency made it a darling of the nootropic underground. The reality check: every supporting study is in cells or rodents, there are zero human clinical trials, and a foundational 2012 biochemistry paper describing its target was later retracted.
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.
Detailed Comparison
| Attribute | Dihexa | 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 | Dihexa is derived from angiotensin IV, a fragment of the renin-angiotensin system that has long been linked to memory in animal work. The leading hypothesis is that it acts on the hepatocyte growth factor (HGF) and its receptor c-Met, a growth-factor system that drives the formation of new dendritic spines and synapses. In cultured hippocampal neurons, dihexa and related angiotensin IV analogs increase spine density, and that effect disappears when the HGF/c-Met system is blocked, which is the main evidence the pathway matters. It is worth being blunt that the exact molecular interaction has been contested, since the original paper proposing direct HGF binding was retracted, so the mechanism is best treated as a working hypothesis rather than settled fact. | 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 | 5-20 mg oral or sublingual daily Once daily, effects can last up to 10 days | 100-300 mcg intranasal or subcutaneous Once daily |
| Administration | Oral, sublingual, or intranasal | Intranasal or subcutaneous injection |
| Typical Duration | Cycles of 2-4 weeks | Research protocols vary, often 2-4 weeks |
| Best Time to Take | Morning | Morning |
Possible Side Effects May vary by individual |
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| Research Summary | The published evidence on dihexa is entirely preclinical. Harding, McCoy and colleagues at Washington State University reported that metabolically stabilized angiotensin IV analogs, including dihexa, restored cognition in scopolamine-impaired and aged rats and stimulated synaptogenesis in cultured neurons (J Pharmacol Exp Ther, 2012 and follow-ups). A 2014 study tied the procognitive and synaptogenic effects of these analogs to the HGF/c-Met system. There are no registered human clinical trials and no published human safety or pharmacokinetic data, so dosing, long-term safety and whether any of the rodent benefit translates to people are all unknown. One important caveat for anyone reading the primary literature: the 2012 paper that first proposed dihexa as an HGF/Met modifier was formally retracted in 2024, which weakens the strongest mechanistic claim. Treat dihexa as an interesting research molecule with promising animal data and a notable evidence gap, not as a proven cognitive enhancer. | 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: Dihexa vs PE-22-28
What is the difference between Dihexa and PE-22-28?
Dihexa is a cognitive peptide that dihexa (n-hexanoic-tyr-ile-(6) aminohexanoic amide) is a small synthetic peptide built from angiotensin iv, engineered at washington state university to be orally active and to cross into the brain. the pitch is bold: it is studied as a procognitive compound that may rebuild synaptic connections, and lab claims of extreme potency made it a darling of the nootropic underground. the reality check: every supporting study is in cells or rodents, there are zero human clinical trials, and a foundational 2012 biochemistry paper describing its target was later retracted. 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, Dihexa or PE-22-28?
Neither is universally "better" - the choice depends on your specific goals. Dihexa 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 Dihexa and PE-22-28 be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using Dihexa 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.