PE-22-28 vs Orexin A
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-1, Hcrt-1
Orexin A (also called hypocretin-1) is a 33-amino-acid brain peptide made by a small cluster of neurons in the hypothalamus, and it is one of the main signals that keeps you awake. People with narcolepsy type 1 have lost most of these neurons, and orexin is undetectable in their spinal fluid. Orexin A itself is not an approved drug, but a few small German studies have sprayed it into the nose of narcolepsy patients and healthy men with measurable effects. Interesting science, very early stage.
Key Comparison Insights
- Both peptides belong to the Cognitive category, suggesting similar primary applications.
- Orexin A has stronger research evidence (Human Trials) compared to PE-22-28 (Animal Studies).
Detailed Comparison
| Attribute | PE-22-28 | Orexin A |
|---|---|---|
| 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 A activates both orexin receptors (OX1R and OX2R) with high affinity. Those receptors sit on brainstem and hypothalamic arousal centers (the histamine, noradrenaline, dopamine and acetylcholine systems), so orexin acts like a stabilizer that keeps the brain locked in the wake state and stops it slipping into REM sleep at the wrong time. Losing it causes narcolepsy: orexin knockout mice and dogs with a broken OX2R gene both develop narcolepsy, and giving orexin A into the brain of narcoleptic mice suppressed cataplexy. Orexin also drives appetite and raises sympathetic nerve activity. A mouse study found orexin A crosses the blood-brain barrier fairly well, and the nasal route is used in humans to deliver more of it to the brain. |
| Common Dosing | 100-300 mcg Once daily | 435 nmol (about 1.5 mg) intranasal Single dose in studies |
| Administration | Intranasal or subcutaneous injection | Intranasal spray |
| Typical Duration | Research protocols vary, often 2-4 weeks | Single doses only in published human studies |
| Best Time to Take | Morning | Morning |
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. | The human data comes from a handful of small, placebo-controlled crossover studies, mostly from one group in Kiel, Germany. In 2008, intranasal orexin A improved smell detection thresholds in 7 narcolepsy patients. In 2011, a single 435 nmol nasal dose before bed in 8 patients did not change nighttime wakefulness but reduced REM sleep and wake-to-REM transitions. In 2014, the same dose given in the morning to 14 patients reduced wake-REM transitions and improved divided attention (fewer errors). In 2022, 500 nmol in 10 healthy men acutely raised sympathetic nerve activity to blood vessels, without changing blood pressure or heart rate. In sleep-deprived monkeys, nasal orexin A reversed some of the drop in memory performance (Deadwyler, 2007). That is the whole human record: single doses, tiny groups, short-term outcomes. The real clinical action has moved to small-molecule drugs that mimic orexin at OX2R. Takeda's oveporexton (brand name Orzeyful) was FDA-approved on August 5, 2026 for narcolepsy type 1, which validates the target but is not the same thing as using the peptide. |
Frequently Asked Questions: PE-22-28 vs Orexin A
What is the difference between PE-22-28 and Orexin A?
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 A is a cognitive peptide that orexin a (also called hypocretin-1) is a 33-amino-acid brain peptide made by a small cluster of neurons in the hypothalamus, and it is one of the main signals that keeps you awake. people with narcolepsy type 1 have lost most of these neurons, and orexin is undetectable in their spinal fluid. orexin a itself is not an approved drug, but a few small german studies have sprayed it into the nose of narcolepsy patients and healthy men with measurable effects. interesting science, very early stage. The main differences lie in their mechanisms of action and clinical applications.
Which is better, PE-22-28 or Orexin A?
Neither is universally "better" - the choice depends on your specific goals. PE-22-28 is typically used for cognitive purposes, while Orexin A 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 A be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using PE-22-28 and Orexin A 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.