Orexin-A
Orexin-A is an endogenous wake-promoting neuropeptide in the Neuromodulator class. Orexin-A is produced by a small population of lateral hypothalamic neurons and binds both orexin receptor 1 and orexin receptor 2, which are Gq-coupled and broadly excitatory. Orexin signalling stabilises wakefulness by exciting monoaminergic and cholinergic arousal nuclei, and also influences feeding, reward and autonomic tone.
For research use only.
Key Facts
- CAS
- 205599-75-3
- Molecular Weight (MW)
- 3561.1 g/mol
- Half-life
- —
- FDA status
- Not Approved
- Administration Route
- intranasal
- Frequency
- —
- Last updated
- Aug 30, 2026
- Reviewed
- Aug 30, 2026
Research summary
Endogenous 33-amino-acid hypothalamic neuropeptide central to arousal and wakefulness. Loss of orexin-producing neurons causes narcolepsy type 1. Studied as an intranasal research compound; not FDA-approved.
Peptide Library's Orexin-A profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Protocol
- Dosage Range
- —
- Frequency
- —
- Cycle
- —
- Administration Route
- intranasal
- Reconstitution Guide
- —
Sequence & molecular data
| Molecular formula | C152H243N47O44S4 |
|---|---|
| Molecular weight | 3561.1 g/mol |
| CAS number | 205599-75-3 |
| PubChem CID | 56842143 |
| FDA UNII | 8RDY08V4VC |
Identifiers link to the public PubChem, FDA Substance Registration (UNII), ChEMBL and DrugBank records for the same entity.
Science
Mechanism of Action
Orexin-A is produced by a small population of lateral hypothalamic neurons and binds both orexin receptor 1 and orexin receptor 2, which are Gq-coupled and broadly excitatory. Orexin signalling stabilises wakefulness by exciting monoaminergic and cholinergic arousal nuclei, and also influences feeding, reward and autonomic tone. Its size and charge limit brain penetration after peripheral administration, which is why intranasal delivery is the route studied.
Studies
- Treatment of Narcolepsy Type 1 With Orexin: A Systematic Review
- Increased CSF hypocretin-1 (orexin-A) in restless legs syndrome
- Hypocretin-1/ Orexin-A fragment1-16 as a potential surrogate marker for diagnosing narcolepsy type 1
- 16-mer hypocretin-1/orexin-A in cerebrospinal fluid to diagnose narcolepsy
- Detection of reduced orexin-A/hypocretin-1 and its fragments by orexin-A "gold-standard" radioimmunoassay
Regulatory & research status
Orexin-A is not an FDA-approved product. It is sold for laboratory research and has no approved medical use.
| FDA status | Not Approved |
|---|---|
| Research status | Research-only compound; no approval pathway listed |
| Availability | Research-Only |
| WADA (sport) | Unknown / Not Listed |
| Library classification | Research-Only |
Benefits
—
Potential Side Effects
No side effects listed yet for this entry.
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
Orexin-A: frequently asked questions
What is Orexin-A?
Endogenous 33-amino-acid hypothalamic neuropeptide central to arousal and wakefulness. Loss of orexin-producing neurons causes narcolepsy type 1. Studied as an intranasal research compound; not FDA-approved.
How does Orexin-A work?
Orexin-A is produced by a small population of lateral hypothalamic neurons and binds both orexin receptor 1 and orexin receptor 2, which are Gq-coupled and broadly excitatory. Orexin signalling stabilises wakefulness by exciting monoaminergic and cholinergic arousal nuclei, and also influences feeding, reward and autonomic tone.
Is Orexin-A FDA approved?
No. Orexin-A is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use.
What peptides are similar to Orexin-A?
Compounds most often compared with Orexin-A include Delta Sleep-Inducing Peptide (DSIP), Epitalon, N-Acetyl Selank Amidate and Noopept. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- Treatment of Narcolepsy Type 1 With Orexin: A Systematic Review — Cureus, 2024External reference
- Increased CSF hypocretin-1 (orexin-A) in restless legs syndrome — Neurology, 2002External reference
- Hypocretin-1/ Orexin-A fragment1-16 as a potential surrogate marker for diagnosing narcolepsy type 1 — Sleep, 2026External reference
- 16-mer hypocretin-1/orexin-A in cerebrospinal fluid to diagnose narcolepsy — Sleep, 2025External reference
- Detection of reduced orexin-A/hypocretin-1 and its fragments by orexin-A "gold-standard" radioimmunoassay — Sleep Med, 2025External reference
Related research, comparisons & guides
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Aug 30, 2026 · Version 1
This Orexin-A profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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