What Is Cligosiban? Definition and What Research Reports
Cligosiban is an investigational, orally administered small-molecule antagonist of the oxytocin receptor — the receptor normally activated by the peptide hormone oxytocin. It was investigated mainly as a candidate oral treatment for lifelong premature ejaculation. Published work includes rodent pharmacology, rat and dog pharmacokinetics, healthy-subject single- and multiple-dose trials, one proof-of-concept trial that reported longer intravaginal ejaculatory latency, and a later phase IIb trial that did not. A separate 2024 laboratory study examined human prostate tissue contractility.
Definition
Cligosiban is an investigational, orally administered small molecule that acts as a selective antagonist at the oxytocin receptor, meaning it blocks rather than mimics signalling at the receptor normally activated by the peptide hormone oxytocin; researchers characterised it as a brain-penetrant, selective oxytocin receptor antagonist in a rodent study that reported inhibition of ejaculatory physiology (PMID 30527053). In the published literature the compound appears almost entirely in the context of lifelong premature ejaculation research, alongside a smaller body of pharmacokinetic work in rats and dogs and one laboratory study of human prostate tissue. This page is for educational purposes only and is not medical advice; consult a licensed physician about any medical question.
What Class of Molecule Is It — and Why Is It in a Peptide Glossary?
Cligosiban is not itself a peptide. It is a synthetic small-molecule drug candidate designed to occupy the oxytocin receptor, a G-protein-coupled receptor whose natural ligand — oxytocin — is a nine-amino-acid peptide. That distinction is the main reason the term surfaces in peptide reference material: readers encountering oxytocin, carbetocin or other oxytocin-related entries frequently meet cligosiban as the counterpart that blocks the same receptor rather than stimulating it.
- Molecular class: synthetic small molecule (not a peptide, not a peptide analogue).
- Target: the oxytocin receptor, described as selectively antagonised and brain-penetrant in rodent pharmacology (PMID 30527053).
- Route studied: oral, in healthy-subject pharmacokinetic trials (PMID 30341006).
- Primary research indication: lifelong premature ejaculation (PMID 31351659).
Antagonist versus agonist
An agonist activates a receptor; an antagonist occupies it and prevents activation by the endogenous ligand. Oxytocin agonists are studied for uterine contraction and social-behaviour endpoints, whereas cligosiban was studied as an antagonist on the hypothesis that oxytocin signalling contributes to the ejaculatory reflex — a hypothesis tested directly in rodents, where the study reported that cligosiban inhibited ejaculatory physiology (PMID 30527053).
How the Term Is Used in Research Writing
In published papers, "cligosiban" is used as the international non-proprietary name of a single defined compound. It appears most often in three kinds of sentences: as the test article in preclinical pharmacology, as the analyte in bioanalytical and pharmacokinetic method papers, and as the active arm in randomised, double-blind, placebo-controlled human trials. Method-focused papers used liquid chromatography with electrospray ionisation tandem mass spectrometry to quantify cligosiban and describe its pharmacokinetics, bioavailability and metabolism in rats (PMID 30472591), and a companion approach was applied to measure cligosiban in dog plasma after oral administration (PMID 31145820).
Because cligosiban is an investigational compound rather than an approved medicine, the literature uses it as a pharmacological tool as much as a therapeutic candidate — for example, to probe whether oxytocin receptor blockade changes contractile behaviour in human tissue.
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Preclinical pharmacology
The rodent work is the origin point for the clinical programme: researchers described cligosiban as a novel, brain-penetrant, selective oxytocin receptor antagonist and reported that it inhibited ejaculatory physiology in rodents (PMID 30527053). Supporting bioanalytical work characterised pharmacokinetics, bioavailability and metabolism of cligosiban in rats (PMID 30472591) and pharmacokinetics in dog plasma following oral dosing (PMID 31145820).
Healthy-subject pharmacokinetics
Two published clusters of early-phase work exist. Three randomised clinical trials in healthy subjects examined the pharmacokinetics, safety and tolerability of single oral doses of cligosiban (PMID 30341006), and two further randomised clinical trials in healthy subjects examined multiple doses with the same set of endpoints (PMID 30612858). Both reports positioned the compound as being in development for premature ejaculation.
Clinical trials in men with lifelong premature ejaculation
The efficacy literature is notable for reporting two different outcomes. In the randomised, double-blind, placebo-controlled proof-of-concept trial known as PEPIX, researchers reported that cligosiban prolonged intravaginal ejaculatory latency and improved patient-reported outcomes in men with lifelong premature ejaculation (PMID 31351659). In the subsequent randomised, double-blind, placebo-controlled phase IIb trial known as PEDRIX, the study reported that cligosiban failed to prolong intravaginal ejaculatory latency in men with lifelong premature ejaculation (PMID 31351660). Anyone summarising cligosiban accurately has to carry both results, because the larger, later trial did not confirm the earlier signal.
Human prostate tissue
Interest in the compound did not end with the ejaculation programme. A 2024 laboratory study reported that the oxytocin antagonist cligosiban reduced human prostate contractility, and the authors framed this as having implications for the treatment of benign prostatic hyperplasia (PMID 38676555). That work was conducted on tissue rather than in patients, so it describes a pharmacological effect rather than a clinical outcome.
Summary Table of the Published Record
| Study type | Model or population | What was reported |
|---|---|---|
| Preclinical pharmacology | Rodents | Inhibition of ejaculatory physiology by a brain-penetrant, selective oxytocin receptor antagonist (PMID 30527053) |
| Bioanalysis / pharmacokinetics | Rat | Pharmacokinetics, bioavailability and metabolism characterised by LC–MS/MS (PMID 30472591) |
| Bioanalysis / pharmacokinetics | Dog | Plasma pharmacokinetics after oral administration (PMID 31145820) |
| Phase I, single dose | Healthy subjects | Pharmacokinetics, safety and tolerability across three randomised trials (PMID 30341006) |
| Phase I, multiple dose | Healthy subjects | Pharmacokinetics, safety and tolerability across two randomised trials (PMID 30612858) |
| Proof-of-concept (PEPIX) | Men with lifelong premature ejaculation | Prolonged intravaginal ejaculatory latency and improved patient-reported outcomes (PMID 31351659) |
| Phase IIb (PEDRIX) | Men with lifelong premature ejaculation | Did not prolong intravaginal ejaculatory latency (PMID 31351660) |
| Tissue pharmacology | Human prostate | Reduced prostate contractility, discussed in relation to benign prostatic hyperplasia (PMID 38676555) |
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Safety and tolerability were named endpoints in the early-phase programme rather than incidental observations. Researchers assessed pharmacokinetics, safety and tolerability of single oral doses in three randomised trials in healthy subjects (PMID 30341006), and the same endpoints were assessed after multiple doses in two further randomised trials in healthy subjects (PMID 30612858). The efficacy trials in men with lifelong premature ejaculation were run as randomised, double-blind, placebo-controlled studies, which is the design that allows adverse events in the active arm to be compared against placebo (PMID 31351659). Detailed adverse-event tables sit in the full texts of those reports; this entry does not reproduce them, and no dose figures are stated here because a glossary definition does not require them.
Regulatory Status
Cligosiban has been described throughout the published record as a compound in development for premature ejaculation rather than as a marketed medicine (PMID 30612858). Investigational compounds of this kind are handled under research-use frameworks and clinical-trial authorisations, not as consumer products. Nothing on this page describes availability, sourcing or personal use.
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Start learning freeRelated Glossary Concepts
- Oxytocin: the endogenous nine-amino-acid peptide hormone whose receptor cligosiban blocks.
- Oxytocin receptor: the G-protein-coupled receptor target named in the rodent pharmacology report (PMID 30527053).
- Intravaginal ejaculatory latency time (IELT): the stopwatch-based primary endpoint used in both the PEPIX and PEDRIX trials (PMID 31351660).
- Brain penetrance: the property, attributed to cligosiban in rodent work, of crossing into the central nervous system (PMID 30527053).
References
- Cligosiban, A Novel Brain-Penetrant, Selective Oxytocin Receptor Antagonist, Inhibits Ejaculatory Physiology in Rodents (The Journal of Sexual Medicine, 2018)
- Pharmacokinetics, Safety, and Tolerability of Single Oral Doses of a Novel Oxytocin Receptor Antagonist—Cligosiban—in Development for Premature Ejaculation: Three Randomized Clinical Trials in Healthy Subjects (The Journal of Sexual Medicine, 2018)
- Pharmacokinetics, Safety, and Tolerability of Multiple Doses of the Novel Oxytocin Receptor Antagonist Cligosiban in Development for Premature Ejaculation: Two Randomized Clinical Trials in Healthy Subjects (The Journal of Sexual Medicine, 2019)
- Pharmacokinetics, bioavailability and metabolism of cligosiban, an antagonist of oxytocin receptor, in rat by liquid chromatography hyphenated with electrospray ionization tandem mass spectrometry (Journal of Pharmaceutical and Biomedical Analysis, 2019)
- Pharmacokinetics of cligosiban in dog plasma after oral administration by liquid chromatography electrospray ionization tandem mass spectrometry (Biomedical Chromatography, 2019)
- The Oxytocin Antagonist Cligosiban Prolongs Intravaginal Ejaculatory Latency and Improves Patient-Reported Outcomes in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Proof-of-Concept Trial (PEPIX) (The Journal of Sexual Medicine, 2019)
- The Oxytocin Antagonist Cligosiban Fails to Prolong Intravaginal Ejaculatory Latency in Men with Lifelong Premature Ejaculation: Results of a Randomized, Double-Blind, Placebo-Controlled Phase IIb Trial (PEDRIX) (The Journal of Sexual Medicine, 2019)
- The oxytocin antagonist cligosiban reduces human prostate contractility: Implications for the treatment of benign prostatic hyperplasia (British Journal of Pharmacology, 2024)
Frequently asked questions
Is cligosiban a peptide?▾
No. Cligosiban is a synthetic small molecule, not a peptide or peptide analogue. It appears in peptide reference material because its target is the oxytocin receptor, the receptor for the peptide hormone oxytocin. Rodent pharmacology described it as a brain-penetrant, selective oxytocin receptor antagonist that inhibited ejaculatory physiology (PMID 30527053).
What was cligosiban studied for?▾
The published programme focused on lifelong premature ejaculation. A randomised, double-blind, placebo-controlled proof-of-concept trial called PEPIX reported prolonged intravaginal ejaculatory latency and improved patient-reported outcomes (PMID 31351659), while the later phase IIb PEDRIX trial reported that cligosiban failed to prolong intravaginal ejaculatory latency in the same population (PMID 31351660).
Why do the two clinical trials disagree?▾
They differed in size and stage of development. PEPIX was a proof-of-concept study that reported a positive effect on intravaginal ejaculatory latency and patient-reported outcomes (PMID 31351659); PEDRIX was a larger phase IIb trial in which the study reported no prolongation of intravaginal ejaculatory latency (PMID 31351660). Researchers generally weight the larger confirmatory trial more heavily.
What did pharmacokinetic studies examine?▾
Animal work characterised pharmacokinetics, bioavailability and metabolism in rats using LC–MS/MS (PMID 30472591) and plasma pharmacokinetics in dogs after oral administration (PMID 31145820). In humans, three randomised trials in healthy subjects examined single oral doses (PMID 30341006) and two further randomised trials examined multiple doses (PMID 30612858), each with pharmacokinetics, safety and tolerability as endpoints.
Has cligosiban been studied outside premature ejaculation?▾
Yes, in laboratory tissue work. A 2024 study reported that the oxytocin antagonist cligosiban reduced human prostate contractility, and the authors discussed implications for benign prostatic hyperplasia (PMID 38676555). That was tissue pharmacology rather than a clinical trial, so it describes a measured effect on prostate tissue rather than a patient outcome.
Is cligosiban an approved medicine?▾
The published literature consistently describes cligosiban as a compound in development for premature ejaculation rather than a marketed product (PMID 30612858). Investigational compounds are studied under clinical-trial and research-use frameworks. This entry is definitional and educational only; it is not medical advice, and a licensed physician is the appropriate source for any clinical question.
What does 'oxytocin receptor antagonist' mean?▾
An antagonist binds a receptor and blocks activation by its natural ligand instead of triggering signalling. For cligosiban the receptor is the oxytocin receptor, and rodent researchers reported that this selective, brain-penetrant blockade inhibited ejaculatory physiology (PMID 30527053) — the pharmacological rationale later tested in randomised placebo-controlled trials in men (PMID 31351659).
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References
This page summarises published research for education — it is not medical advice, and nothing here is a recommendation to use, purchase, or dose any substance. Study parameters described are what researchers reported, not instructions. Consult a qualified clinician before any health decision.