What Is Nolasiban? Definition and What Research Reports

Definition

Nolasiban is an investigational oxytocin receptor antagonist: a molecule that binds the oxytocin receptor and blocks the signalling that oxytocin would otherwise trigger there. It appears in the published literature almost entirely within reproductive medicine, where researchers have examined it in human uterine (myometrial) and amnion tissue, in healthy female volunteers, and in randomised clinical trials of women undergoing embryo transfer after in vitro fertilisation (IVF) (PMID 33534895). The term is used in research writing as the name of a specific antagonist compound, usually alongside atosiban, the peptide oxytocin receptor antagonist with which it has repeatedly been compared in human tissue studies (PMID 28188254). This page is for educational purposes only and is not medical advice; consult a licensed physician about any medical or reproductive question.

What class of molecule is it?

Nolasiban belongs to the class of oxytocin receptor antagonists. That class contains two structurally different groups. The first is peptide-based: atosiban is a modified analogue of the nine–amino-acid peptide hormone oxytocin itself. The second is non-peptide small molecules designed to occupy the same receptor without being built from an amino-acid backbone; nolasiban is described in the literature as a member of this second group. Because the two groups reach the same receptor by different chemistry, investigators have treated them as pharmacologically distinct rather than interchangeable, and researchers reported differential effects of atosiban and nolasiban on oxytocin receptor–mediated signalling in human amnion and myometrium (PMID 28188254).

Where the name comes from

Nolasiban is an international nonproprietary-style generic name. The -siban stem is the naming convention used for oxytocin receptor antagonists — the same stem that appears in atosiban — which is why the two compounds are so often named in the same sentence in titles and abstracts.

How the term is used in peptide research

Strictly speaking, nolasiban is not a peptide. It is catalogued in peptide-adjacent glossaries for three reasons:

• Its target is a peptide-hormone receptor. Oxytocin is a nonapeptide, so any literature search on oxytocin biology surfaces nolasiban as a receptor-blocking tool compound.
• Its comparator is a peptide drug. Atosiban, an oxytocin analogue, is the reference antagonist in the human-tissue work that also tested nolasiban (PMID 30962532).
• It illustrates peptide versus small-molecule design. Papers comparing the two compounds are frequently cited when authors discuss why replacing a peptide antagonist with a non-peptide one can change downstream signalling rather than simply reproduce it (PMID 28188254).

In practice, when a reader encounters "nolasiban" in a paper, it is functioning as the name of an investigational oxytocin receptor antagonist under study — not as a research peptide, a growth-factor fragment, or a secretagogue.

What the published literature reports

Receptor signalling in human tissue

The 2017 Molecular Pharmacology study compared atosiban and nolasiban in human amnion and myometrium and reported differential effects of the two antagonists on oxytocin receptor–mediated signalling, indicating that blocking the same receptor with a peptide versus a non-peptide compound did not produce identical downstream results (PMID 28188254). That finding is the usual citation given when authors argue that oxytocin receptor antagonists should be characterised individually rather than treated as one homogeneous class.

Uterine contractility and inflammatory signalling

A 2019 Scientific Reports paper examined both antagonists in human myometrium and reported that atosiban and nolasiban inhibited prostaglandin F_2α-induced contractions and inflammatory responses in that tissue (PMID 30962532). The researchers framed the work around crosstalk between prostaglandin and oxytocin pathways in the uterus, which is why the result is cited in discussions of uterine quiescence rather than of oxytocin signalling alone (PMID 30962532).

Mechanism in assisted reproductive technology

A 2021 report in Reproductive BioMedicine Online investigated the mechanism of action of nolasiban in the assisted reproductive technology (ART) setting using healthy female volunteers, addressing how an oxytocin receptor antagonist might act around the time of embryo transfer (PMID 34167897). This is the study most often cited when authors describe the rationale linking receptor blockade to the uterine environment in ART (PMID 34167897).

Clinical trials in embryo transfer

A 2021 analysis in Human Reproduction pooled three randomised clinical trials to evaluate the effect of nolasiban on pregnancy rates in women undergoing embryo transfer following IVF (PMID 33534895). That publication is the principal clinical reference for the compound; readers interested in the trial-level numbers, endpoints and confidence intervals should consult the paper itself, as this glossary entry does not reproduce them (PMID 33534895).

Study map at a glance

Cardiac Safety: What Studies Report

The safety literature specific to nolasiban that is indexed alongside the studies above is narrow. A 2021 Scientific Reports paper described a randomised cohort of healthy female volunteers and reported confirmation of the cardiac safety of nolasiban in that cohort (PMID 33739022). Cardiac-repolarisation assessment of this kind is a standard regulatory step for investigational compounds and speaks only to the endpoints and population that the study examined; it is not a general statement about tolerability across other groups (PMID 33739022). Broader adverse-event reporting for nolasiban sits within the individual randomised trials summarised in the pooled clinical analysis (PMID 33534895).

What this entry does not cover

This glossary page does not list doses, schedules or administration details, and it does not describe outcomes outside the scope of the titles and abstracts of the papers cited here. Nolasiban appears in the literature as an investigational compound studied under clinical-trial conditions with medical supervision, and nothing on this page should be read as a suggestion that it is available for, or appropriate for, any personal use. Anyone evaluating oxytocin receptor pharmacology for clinical or academic purposes should read the primary publications in full and discuss them with a qualified professional.

Related glossary terms

• Oxytocin — the nine–amino-acid peptide hormone whose receptor nolasiban antagonises.
• Atosiban — the peptide oxytocin receptor antagonist used as the comparator in human-tissue studies of nolasiban (PMID 28188254).
• Myometrium — the uterine smooth-muscle layer in which contraction studies of both antagonists were performed (PMID 30962532).
• Receptor antagonist — a molecule that occupies a receptor and prevents the natural ligand from activating it.

References

• Differential Effects of Oxytocin Receptor Antagonists, Atosiban and Nolasiban, on Oxytocin Receptor-Mediated Signaling in Human Amnion and Myometrium (Molecular Pharmacology, 2017)
• Oxytocin Receptor Antagonists, Atosiban and Nolasiban, Inhibit Prostaglandin F2α-induced Contractions and Inflammatory Responses in Human Myometrium (Scientific Reports, 2019)
• The mechanism of action of oxytocin antagonist nolasiban in ART in healthy female volunteers (Reproductive BioMedicine Online, 2021)
• Effect of the oxytocin receptor antagonist nolasiban on pregnancy rates in women undergoing embryo transfer following IVF: analysis of three randomised clinical trials (Human Reproduction, 2021)
• Confirmation of the cardiac safety of nolasiban in a randomised cohort of healthy female volunteers (Scientific Reports, 2021)