Evidence Snapshot
What this grade covers
A for identity and receptor pharmacology; B/C for laboratory physiology; E for human therapeutic efficacy, safety, approval, wakefulness, cognition, narcolepsy treatment, or dosing.
Regulatory Context
Orexin B is an endogenous research neuropeptide. No FDA-approved native Orexin B replacement product or verified direct human administration trial was identified. Approved orexin-system drugs and investigational synthetic OX2 agonists are different molecules and do not establish approval or efficacy for native Orexin B.
Research Takeaway
Orexin B/hypocretin-2 is a native linear 28-amino-acid neuropeptide derived from prepro-orexin.
See all 9 evidence claims →Quick Summary
Orexin B, also called hypocretin-2, is a native 28-amino-acid hypothalamic neuropeptide involved in orexin-receptor signaling. Evidence for native Orexin B consists primarily of receptor, structural, cellular, and animal research. No verified direct human administration trial establishes native Orexin B efficacy, safety, pharmacokinetics, or dosing.
Mechanism & Research Overview
Orexin B activates orexin receptors and has greater relative activity at OX2R than at OX1R compared with Orexin A, but this does not make it clinically selective or interchangeable with synthetic OX2 agonists. Native Orexin B, Orexin A, modified peptide analogues, receptor antagonists, and nonpeptide agonists must remain separate evidence categories.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Orexin B/hypocretin-2 is a native linear 28-amino-acid neuropeptide derived from prepro-orexin.
Supported
Orexin B and Orexin A are distinct peptides and are not dose-equivalent or clinically interchangeable.
Sources: Orexin B compound record
Supported
Native Orexin B participates in OX1R/OX2R receptor signaling, with greater relative OX2R preference than Orexin A in receptor studies.
Sources: Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior; Characterization of Recombinant Human Orexin Receptors; Structure-Activity Studies of Orexin A and Orexin B
Supported
Evidence for native Orexin B is primarily structural, receptor, cellular, and animal evidence.
Sources: Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior; The hypocretins: hypothalamus-specific peptides with neuroexcitatory activity; Distinct recognition of OX1 and OX2 receptors by orexin peptides
Supported
No verified direct human administration study establishes native Orexin B therapeutic efficacy, safety, pharmacokinetics, or dosing.
Sources: Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior; The hypocretins: hypothalamus-specific peptides with neuroexcitatory activity; Distinct recognition of OX1 and OX2 receptors by orexin peptides
Supported
Human evidence for synthetic nonpeptide OX2 agonists cannot be transferred to native Orexin B.
Supported
Findings from modified Orexin B analogues cannot automatically be attributed to native human Orexin B.
Sources: Signaling Profile of Recombinant Human Orexin-2 Receptor
Supported
No FDA-approved native Orexin B replacement drug product was identified.
Sources: 503A Bulk Drug Substances Categories, Updated May 14, 2026; FDA Drug Approvals and Databases; ClinicalTrials.gov Search Portal
Supported
Human long-term, cardiovascular, neurologic, psychiatric, reproductive, and repeated-administration safety remain unestablished for native Orexin B.
Sources: Contribution of orexin in hypercapnic chemoreflex: evidence from genetic and pharmacological disruption and supplementation studies in mice; The role of orexin-B/orexin 2 receptor in myocardial protection
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
Potential central nervous system, autonomic, respiratory, cardiovascular, and metabolic effects are incompletely characterized in humans.Safety Consideration
Modified Orexin B analogues, including [Ala11]orexin-B used in some receptor-selectivity studies, cannot be treated as native Orexin B; findings from such analogues are not automatically attributable to native Orexin B.Safety Consideration
Long-term and repeated-administration safety are unknown.Safety Consideration
Potential concerns include excessive arousal, insomnia, anxiety, agitation, or panic; autonomic activation, blood-pressure, heart-rate, and thermoregulatory effects; appetite and metabolic changes; and receptor desensitization or altered sleep architecture. Relative OX2 preference does not establish clinical selectivity or safety.Safety Consideration
Uncertain CNS delivery and short peptide stability; species-sequence substitution; aggregation, peptide impurities, immunogenicity, sterility, and endotoxins; unknown cardiovascular, neurologic, psychiatric, reproductive, pregnancy, pediatric, and chronic-use risks; and unknown interactions with stimulants, sedatives, antidepressants, wake-promoting drugs, and orexin antagonists.
Research Areas Being Studied
Research areas discussed on this page reflect the Sleep / Circadian category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Danavorexton OX2R-Agonist Human Study ():
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Danavorexton OX2R-Agonist Human Study | Danavorexton is a synthetic, nonpeptide OX2R agonist studied in humans. It is a distinct molecular class from native Orexin A/Orexin B. Results from danavorexton, oveporexton, or another synthetic receptor agonist cannot establish the identity, stability, brain penetration, dosing, safety, or effectiveness of native orexin peptide products -- used here only as an identity/evidence boundary, not as orexin-peptide evidence. |
Animal / Cell / Preclinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Orexin A but not orexin B regulates lipid metabolism and leptin secretion in isolated porcine adipocytes | 2018 | Isolated porcine adipocytes and adipose explants | Orexin A changed several metabolic endpoints, while Orexin B did not show those effects in this model. | Species- and tissue-specific negative result; not human systemic evidence. | |
| The role of orexin-B/orexin 2 receptor in myocardial protection | 2018 | Cardiac ischemia/reperfusion models | Orexin B/OX2 receptor signaling was associated with selected myocardial-protection endpoints in preclinical models. | Preclinical cardiac results do not establish human cardiovascular benefit or safety. | |
| Contribution of orexin in hypercapnic chemoreflex: evidence from genetic and pharmacological disruption and supplementation studies in mice | 2007 | Mouse respiratory chemoreflex experiments | Orexin signaling contributed to ventilatory responses to carbon dioxide in wakefulness. | Respiratory effects are context-dependent and underscore possible autonomic risk. | |
| Distinct recognition of OX1 and OX2 receptors by orexin peptides | 2003 | Receptor-binding and cellular signaling assays | Compared how Orexin A and Orexin B interact with OX1 and OX2 receptor subtypes, supporting distinct pharmacology. | In vitro receptor pharmacology does not predict full human safety or clinical effects. | |
| Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior | 1998 | Receptor deorphanization, rodent brain expression, and animal feeding experiments | Identified orexin A and B as endogenous ligands for two receptors and described hypothalamic expression and feeding-related effects. | Foundational preclinical biology; not human treatment evidence. | |
| The hypocretins: hypothalamus-specific peptides with neuroexcitatory activity | 1998 | Molecular identification and neuronal studies | Independently described hypocretin-1 and hypocretin-2 as hypothalamic neuroexcitatory peptides. | Foundational discovery work does not establish administered-human safety. | |
| Characterization of Recombinant Human Orexin Receptors | Orexin A activates both OX1R and OX2R with high functional activity at each. Orexin B activates OX2R efficiently but has substantially weaker functional activity at OX1R than Orexin A, so the two peptides must not be treated as interchangeable or dose-equivalent. | ||||
| Signaling Profile of Recombinant Human Orexin-2 Receptor | Cell and receptor-signaling research supports OX2R-mediated arousal signaling, receptor signaling and desensitization. These findings remain preclinical/cellular and do not establish human administered-Orexin-B efficacy or safety. | ||||
| Solution Structure of Human Hypocretin-2/Orexin-B | Orexin B, also called hypocretin-2, is an endogenous linear 28-amino-acid neuropeptide generated from prepro-orexin. The mature human peptide is C-terminally amidated. Human and rodent Orexin B sequences are not identical; species-specific sequence must be verified. | ||||
| Structure-Activity Studies of Orexin A and Orexin B | Structure-activity relationships for Orexin A and Orexin B are concentrated in the C-terminal region. Orexin B is often described as relatively OX2-preferring, but it is not an absolutely selective OX2R ligand, and results from a synthetic selective OX2R agonist cannot be assigned to native Orexin B. |
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| 503A Bulk Drug Substances Categories, Updated May 14, 2026 | 2026 | Neither Orexin A nor Orexin B was identified as a current individually evaluated substance in the reviewed FDA 503A bulk-substance category list or FDA significant-safety-risk table as of this update. Absence from those lists is not approval, a safety determination, or authorization to compound. | |||
| Orexin B compound record | 2026 | Chemical identity database record | PubChem records Orexin B as a defined endogenous peptide compound. | An identity record does not indicate FDA approval or human-administration evidence. | |
| ClinicalTrials.gov Search Portal | General trial-registry search portal used as part of this review's regulatory/trial-landscape check. | ||||
| FDA Drug Approvals and Databases | No FDA-approved Orexin A or Orexin B peptide drug or indication was identified in the reviewed FDA drug databases. |
Review Articles / Secondary Sources
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Orexin (hypocretin) receptor agonists and antagonists for treatment of sleep disorders: rationale for development and current status | 2013 | Narrative review of orexin biology and drug development | Reviews the role of orexin signaling in wakefulness, narcolepsy, and receptor-targeted drug development. | Review evidence must not be presented as a primary trial of Orexin A or B. |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
This page concerns native Orexin B/hypocretin-2. Evidence from Orexin A, modified Orexin B analogues, synthetic OX2 agonists, or orexin antagonists is included only when needed to define an evidence boundary. It does not provide treatment, administration, or dosing guidance.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-07-30.
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