Nociceptin (Orphanin FQ)
Evidence: CCognitive / Neuro
Evidence Snapshot
What this grade covers
Exact mature Nociceptin / Orphanin FQ. Small randomized controlled human studies directly administered the endogenous peptide, including local muscular and intravesical administration. Evidence remains small, route-specific, and disease-context-specific; it does not establish broad analgesic, psychiatric, or systemic therapeutic efficacy.
Regulatory Context
Nociceptin (Orphanin FQ) is an investigational endogenous peptide. No FDA-approved Nociceptin therapeutic product has been identified; NOP-receptor-targeting drug development programs are a distinct, separate class and do not represent FDA approval of Nociceptin itself.
Research Takeaway
Nociceptin and Orphanin FQ are two names for the same 17-amino-acid mature peptide produced from the human PNOC precursor; Nocistatin and Orphanin FQ2 are different mature products of that precursor.
Evidence boundary: Sibling PNOC products and synthetic NOP-receptor drugs are not Nociceptin.
See all 7 evidence claims →Quick Summary
Nociceptin, also called Orphanin FQ, is a 17-amino-acid mature human peptide produced from the PNOC precursor - the two names refer to the same molecule. It is distinct from Nocistatin and Orphanin FQ2, two other mature peptides from the same precursor, and from synthetic NOP-receptor drugs such as cebranopadol. Small randomized, placebo-controlled human studies have directly administered exact Nociceptin by local muscular and intravesical (bladder) routes. The strongest human signal comes from small exploratory trials in neurogenic detrusor overactivity (a bladder condition), where intravesical Nociceptin improved bladder-capacity measures; this evidence is route- and condition-specific and does not establish broad analgesic, psychiatric, or systemic therapeutic efficacy.
Mechanism & Research Overview
In a small randomized double-blind local muscle experiment, Nociceptin increased tenderness without producing reported pain under the tested conditions - a nuanced pharmacological profile rather than a simple pain-causing or pain-relieving effect. In two small randomized, placebo-controlled trials in patients with neurogenic detrusor overactivity (a bladder condition related to spinal cord injury), intravesical Nociceptin/Orphanin FQ improved bladder-capacity measures and, over ten days of dosing in one exploratory trial, reduced daily leakage episodes. These findings are specific to local/intravesical administration in a selected patient population and do not generalize to systemic or oral use. Clinical findings for synthetic NOP-receptor agonists such as cebranopadol or sunobinop are a separate drug-development context and cannot be used as efficacy evidence for the endogenous peptide.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Nociceptin and Orphanin FQ are two names for the same 17-amino-acid mature peptide produced from the human PNOC precursor; Nocistatin and Orphanin FQ2 are different mature products of that precursor.
Does not establish
Evidence boundary: Sibling PNOC products and synthetic NOP-receptor drugs are not Nociceptin.
Sources: PNOC prepronociceptin [Homo sapiens]
Supported
Exact Nociceptin/Orphanin FQ has been administered directly to humans in small controlled experimental studies.
Does not establish
Evidence boundary: Human administration is established, but the evidence is route- and indication-specific and remains small.
Sources: Does nociceptin play a role in pain disorders in man?; Urodynamic effects of intravesical nociceptin/orphanin FQ in neurogenic detrusor overactivity: a randomized, placebo-controlled, double-blind study; Daily intravesical instillation of 1 mg nociceptin/orphanin FQ for the control of neurogenic detrusor overactivity: a multicenter, placebo controlled, randomized exploratory study
Supported
In a small randomized double-blind muscle experiment, local Nociceptin increased tenderness without producing reported pain under the tested conditions.
Does not establish
Evidence boundary: Local experimental muscle administration cannot establish systemic analgesic or hyperalgesic efficacy.
Sources: Does nociceptin play a role in pain disorders in man?
Supported
Small randomized studies in neurogenic detrusor overactivity found that intravesical Nociceptin/Orphanin FQ increased bladder-capacity measures relative to placebo.
Does not establish
Evidence boundary: This evidence applies to intravesical administration in selected neurogenic bladder populations and must not be generalized to other routes or urinary conditions.
Sources: Urodynamic effects of intravesical nociceptin/orphanin FQ in neurogenic detrusor overactivity: a randomized, placebo-controlled, double-blind study; Daily intravesical instillation of 1 mg nociceptin/orphanin FQ for the control of neurogenic detrusor overactivity: a multicenter, placebo controlled, randomized exploratory study
Supported
In an 18-patient exploratory randomized study, ten days of intravesical Nociceptin/Orphanin FQ reduced leakage frequency and increased diary bladder capacity compared with the study's placebo group.
Does not establish
Evidence boundary: Very small exploratory trial; not replicated at large scale and not evidence for systemic or oral use.
Supported
The available direct-human safety evidence for Nociceptin is limited to small, short-duration, route-specific studies and does not define a broad systemic safety profile.
Does not establish
Evidence boundary: Lack of major reported problems in these small experiments is not proof of long-term safety.
Sources: Does nociceptin play a role in pain disorders in man?; Urodynamic effects of intravesical nociceptin/orphanin FQ in neurogenic detrusor overactivity: a randomized, placebo-controlled, double-blind study; Daily intravesical instillation of 1 mg nociceptin/orphanin FQ for the control of neurogenic detrusor overactivity: a multicenter, placebo controlled, randomized exploratory study
Supported
Clinical findings for synthetic NOP-receptor agonists such as cebranopadol or sunobinop are receptor-drug context and cannot be used as efficacy evidence for the endogenous Nociceptin peptide.
Does not establish
Evidence boundary: Receptor target overlap does not establish molecular equivalence.
Sources: PNOC prepronociceptin [Homo sapiens]; Nociceptin/Orphanin FQ and Urinary Bladder
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
Human findings come from local muscle and intravesical (bladder) administration in small, selected populations; they do not establish systemic or oral effects.Safety Consideration
A local muscle study found Nociceptin increased tenderness without producing reported pain, indicating a nuanced rather than straightforward analgesic or pro-nociceptive effect.Safety Consideration
Available human studies are small, short-duration, and route-specific; long-term or systemic safety has not been characterized.Safety Consideration
Findings for synthetic NOP agonists/antagonists such as cebranopadol or sunobinop reflect a distinct drug-development program and are not evidence for the endogenous peptide.
Research Areas Being Studied
Research areas discussed on this page reflect the Cognitive / Neuro category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Daily intravesical instillation of 1 mg nociceptin/orphanin FQ for the control of neurogenic detrusor overactivity: a multicenter, placebo controlled, randomized exploratory study ():
- Does nociceptin play a role in pain disorders in man? ():
- Urodynamic effects of intravesical nociceptin/orphanin FQ in neurogenic detrusor overactivity: a randomized, placebo-controlled, double-blind study ():
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Daily intravesical instillation of 1 mg nociceptin/orphanin FQ for the control of neurogenic detrusor overactivity: a multicenter, placebo controlled, randomized exploratory study | 18 patients with neurogenic detrusor overactivity incontinence on clean intermittent self-catheterization; 9 active, 9 placebo | Ten days of intravesical N/OFQ improved bladder-capacity measures and reduced daily leakage episodes versus baseline/placebo in this exploratory randomized study; no significant procedure-related problems or significant side effects were reported. | |||
| Does nociceptin play a role in pain disorders in man? | Healthy human subjects; local muscle administration; randomized, placebo-controlled, balanced double-blind arm with n=10 plus an open-label n=4 arm | Local nociceptin administration did not produce pain in the tested designs but increased local tenderness in the randomized trapezius-muscle arm. | |||
| Urodynamic effects of intravesical nociceptin/orphanin FQ in neurogenic detrusor overactivity: a randomized, placebo-controlled, double-blind study | 14 patients with neurogenic detrusor overactivity due to spinal cord injury | Acute intravesical N/OFQ increased bladder-capacity/urodynamic measures relative to placebo in this small randomized study. |
Animal / Cell / Preclinical Data
No Animal / Cell / Preclinical Data Listed Yet
This section will be updated as sources are added.
Regulatory Documents & Official Trial Registries
No Regulatory Documents & Official Trial Registries Listed Yet
This section will be updated as sources are added.
Review Articles / Secondary Sources
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Nociceptin/Orphanin FQ and Urinary Bladder | Review of preclinical and human bladder literature | Reviews the bladder evidence and distinguishes exact N/OFQ studies from modified NOP agonists such as UFP-112. | |||
| PNOC prepronociceptin [Homo sapiens] | Homo sapiens identity record | PNOC is processed into multiple distinct peptides including Nociceptin, Nocistatin, and Orphanin FQ2; Nociceptin and Orphanin FQ are two names for the same mature peptide. | No source link available |
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
Educational information only. This page summarizes published and official research and does not provide medical advice, a recommendation, or instructions for human use.
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 2026-08-24.
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