PE-22-28 vs Orexin B
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
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.
Also: Hypocretin-2, Hcrt-2
Orexin B (hypocretin-2) is the sister peptide of orexin A. Both are cut from the same precursor protein in the hypothalamus and both help regulate wakefulness and appetite. Orexin B is a 28-amino-acid linear peptide that mostly acts through the OX2R receptor, the receptor most tied to narcolepsy. The catch for anyone hoping to use it: it falls apart fast in the blood, barely reaches the brain from the bloodstream, and has never been given to humans in a published study.
Key Comparison Insights
- Both peptides belong to the Cognitive category, suggesting similar primary applications.
Detailed Comparison
| Attribute | PE-22-28 | Orexin B |
|---|---|---|
| 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 | 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. | Orexin B binds OX2R about as strongly as orexin A does, but binds OX1R roughly 20 times more weakly, so it behaves as a relatively OX2R-preferring signal. OX2R is the receptor that matters most for staying awake and keeping REM sleep in its place: a broken OX2R gene causes inherited narcolepsy in dogs, and the newest approved narcolepsy drug is an OX2R agonist. Structurally, orexin B is a linear chain without the two disulfide bridges that make orexin A more stable. A 1999 mouse study found that injected orexin B was rapidly degraded in blood and none reached the brain intact, while orexin A crossed easily. That is the main reason human research has focused on orexin A. |
| Common Dosing | 100-300 mcg Once daily | No established human dose Not established |
| Administration | Intranasal or subcutaneous injection | Intracerebroventricular or local injection in animal studies |
| Typical Duration | Research protocols vary, often 2-4 weeks | Acute single-dose animal experiments |
| Best Time to Take | Morning | Not established |
Possible Side Effects May vary by individual |
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| Research Summary | 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. | Orexin B has been studied for almost 30 years, but almost entirely as a research tool in animals and tissue. The 1998 discovery paper in Cell (Sakurai and colleagues) showed both orexins increased food intake when injected into rat brains. Work since then has mapped its role in arousal, feeding, and more recently pain: 2026 mouse research found orexin B acting at OX2R could trigger migraine-like headache pain in male but not female mice. We could not find any published study giving orexin B to humans, by nose or by injection, and no registered clinical trials. If you want the orexin story with actual human data, see orexin A. Orexin B on its own is a preclinical compound with a real biological role and no tested human use. |
Frequently Asked Questions: PE-22-28 vs Orexin B
What is the difference between PE-22-28 and Orexin B?
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. Orexin B is a cognitive peptide that orexin b (hypocretin-2) is the sister peptide of orexin a. both are cut from the same precursor protein in the hypothalamus and both help regulate wakefulness and appetite. orexin b is a 28-amino-acid linear peptide that mostly acts through the ox2r receptor, the receptor most tied to narcolepsy. the catch for anyone hoping to use it: it falls apart fast in the blood, barely reaches the brain from the bloodstream, and has never been given to humans in a published study. The main differences lie in their mechanisms of action and clinical applications.
Which is better, PE-22-28 or Orexin B?
Neither is universally "better" - the choice depends on your specific goals. PE-22-28 is typically used for cognitive purposes, while Orexin B is used for cognitive. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can PE-22-28 and Orexin B be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using PE-22-28 and Orexin B 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.