Orexin B
Aliases: Hypocretin-2
Last verified: 2026-09-24
The short version
Orexin B is Orexin A's younger brother in every sense: shorter, more OX2R-selective, and considerably less studied. Its gray presence is even more extravagant than Orexin A's — sold as 'more compelling' due to receptor selectivity, although the literature neither confirms nor denies this, being practically nonexistent. If Orexin A has a couple of pilots, Orexin B has nuances. The general principle stands: the orexin system is treated with molecules, not peptides; this is a laboratory reagent that wandered into a catalog.
Identity & type
- Molecular type
- neuropeptide
- Molecular weight
- ~3.1 kDa
- Origin
- The natural human neuropeptide from the prepro-orexin precursor; the gray version is a synthetic analog.
Mechanism of action
A 28-amino-acid neuropeptide from the same precursor as Orexin A; more selective for the OX2R receptor (responsible for REM control and wakefulness stability), shorter and less studied than Orexin A.
not confirmed in humans
Dosing & routes
Official / clinical context
No official context exists.
Regulator-approved labeling and published study designs — never a recommendation.
Community-reported practice
Rare; the same intranasal patterns as Orexin A, without reported differences in experience.
Unverified self-reports. Not medical advice. Not endorsement.
Protocol — official vs community
Official / label
No approved protocol exists — preclinical agent. Orexin B has only experimental intranasal/ICV µg dosing in animal and small pilot work; no human regimen has been defined.
Duration: —
Its OX2R selectivity makes it scientifically interesting for sleep-wake stability, but it is the less-studied sibling of Orexin A in a field that has already moved to small-molecule agonists.
Community (anecdotal)
Structured protocol data for this entry is coming.
Human evidence
Practically none — a few small CSF measurement findings in narcolepsy (diagnostic, not therapeutic).
Preclinical evidence
Basic receptor pharmacology and animal models; without larger-scale interventional studies.
Known risks
- Everything unknown in humanstheoretical
Teal: characterized in clinical/labeling contexts. Amber: theoretical or reported outside controlled settings.
Unknowns & evidence gaps
- Everything — from bioavailability to effect
Frequently asked questions
References
- Orexin receptor pharmacology literature (OX1R/OX2R selectivity)