Orexin B vs Davunetide
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
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.
Also: NAP, AL-108
Davunetide (NAP) is an eight-amino-acid fragment (NAPVSIPQ) of activity-dependent neuroprotective protein (ADNP), discovered at Tel Aviv University and given as a nasal spray. It was meant to protect brain cells by stabilizing microtubules, the scaffolding that tau normally supports. Its big test, a phase 2/3 trial in progressive supranuclear palsy (PSP), failed cleanly in 2012, and development stalled. It has since been revived by its inventors, who argue it works in women and are pursuing ADNP syndrome, but those claims rest on reanalyses of old data, not a new successful trial.
Key Comparison Insights
- Both peptides belong to the Cognitive category, suggesting similar primary applications.
- Davunetide has stronger research evidence (Human Trials) compared to Orexin B (Preclinical).
Detailed Comparison
| Attribute | Orexin B | Davunetide |
|---|---|---|
| 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 | 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. | NAP comes from ADNP, a protein essential for brain development. In cell and animal studies it interacts with microtubule end-binding proteins (EB1 and EB3), promoting microtubule stability and reducing tau phosphorylation, which is why it was aimed at tauopathies like PSP and Alzheimer's disease. Mutations in the ADNP gene itself cause ADNP syndrome (Helsmoortel-Van der Aa syndrome), and in ADNP-deficient mice NAP improved some behavioral and neural measures, the rationale for that newer program. The PSP trial did not include target-engagement measures, so it never showed the drug was actually doing this in human brains. |
| Common Dosing | No established human dose Not established | 30 mg intranasal twice daily (PSP trial dose) Once or twice daily |
| Administration | Intracerebroventricular or local injection in animal studies | Intranasal spray (an IV form, AL-208, was tested in cardiac surgery) |
| Typical Duration | Acute single-dose animal experiments | 12 weeks to 52 weeks in trials |
| Best Time to Take | Not established | Twice daily (trial schedule) |
Possible Side Effects May vary by individual |
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| Research Summary | 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. | The headline result is negative. In the phase 2/3 PSP trial (Boxer and colleagues, Lancet Neurology 2014), 313 patients got 30 mg intranasal davunetide twice daily or placebo for 52 weeks. Disease progression was identical in both groups on both primary measures (PSP Rating Scale and Schwab and England daily living scale), and the authors concluded davunetide is not an effective treatment for PSP. Earlier phase 2 work was mixed: a 12-week trial in 144 people with amnestic mild cognitive impairment hinted at working-memory benefits, and a schizophrenia trial missed one co-primary endpoint while hitting another. The original developer, Allon Therapeutics, stopped investing and was later absorbed by Paladin Labs. The revival comes from the inventor's group: post hoc reanalyses of the PSP data (Translational Psychiatry 2023, Molecular Psychiatry 2026) report that women declined faster than men and that davunetide slowed decline in women only. A similar sex-split reanalysis of the MCI trial was published in 2024. These findings are interesting but are subgroup analyses of trials that failed overall, done by researchers tied to the company now developing the drug (ExoNavis Therapeutics), so they need a new prospective trial to mean much. ExoNavis has said a phase 3 in children with ADNP syndrome began in 2024, but Alzforum could not find it in trial registries. Davunetide holds FDA orphan and rare pediatric disease designations and EMA orphan status for ADNP syndrome. |
Frequently Asked Questions: Orexin B vs Davunetide
What is the difference between Orexin B and Davunetide?
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. Davunetide is a cognitive peptide that davunetide (nap) is an eight-amino-acid fragment (napvsipq) of activity-dependent neuroprotective protein (adnp), discovered at tel aviv university and given as a nasal spray. it was meant to protect brain cells by stabilizing microtubules, the scaffolding that tau normally supports. its big test, a phase 2/3 trial in progressive supranuclear palsy (psp), failed cleanly in 2012, and development stalled. it has since been revived by its inventors, who argue it works in women and are pursuing adnp syndrome, but those claims rest on reanalyses of old data, not a new successful trial. The main differences lie in their mechanisms of action and clinical applications.
Which is better, Orexin B or Davunetide?
Neither is universally "better" - the choice depends on your specific goals. Orexin B is typically used for cognitive purposes, while Davunetide is used for cognitive. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can Orexin B and Davunetide be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using Orexin B and Davunetide 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.