Barusiban
Also known as: Barusiban, FE 200440, FE200440, SRI-37618
Source Barusiban at Peptiology
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Summary
Barusiban is an investigational peptide that selectively blocks the oxytocin receptor. It has been explored as a tocolytic to halt preterm uterine contractions and, more recently, as an adjunct in assisted reproduction to reduce uterine activity around embryo transfer. The compound is administered by injection (intravenous or subcutaneous) and remains under clinical evaluation, with no regulatory approval for any indication.
Mechanism of Action
Barusiban binds with high affinity to the oxytocin receptor (OTR) while showing markedly lower affinity for the vasopressin V1A receptor. By occupying the OTR, it prevents oxytocin‑mediated signalling that drives uterine smooth‑muscle contraction. This antagonism is intended to suppress premature labour contractions and, in the context of embryo transfer, to minimise uterine contractility that could impede implantation.
What the Research Shows
Preclinical work demonstrated limited placental transfer of barusiban (5‑11% of maternal levels) in rabbit, cynomolgus monkey and ex‑vivo human cotyledon models, suggesting low fetal exposure. A 2009 randomized trial in women at 34‑35 weeks gestation found a single intravenous bolus of barusiban did not reduce uterine contractions nor increase the proportion of women remaining undelivered at 48 hours compared with placebo. In assisted reproduction, a Cochrane review identified one subcutaneous barusiban trial (255 participants) that reported no clear effect on clinical pregnancy and mild injection‑site reactions. A broader systematic review of oxytocin receptor antagonists (including barusiban) reported a modest increase in clinical pregnancy rates around embryo transfer, but live‑birth outcomes were unchanged and evidence was of low certainty.
Reported Benefits
Limited data suggest barusiban may be safe for maternal and fetal exposure, with no serious adverse events reported in the available trials. In the assisted‑reproduction context, the overall class of oxytocin antagonists has shown a small but statistically significant rise in clinical pregnancy rates, indicating a potential benefit of reducing uterine contractility during embryo transfer. However, barusiban‑specific benefits remain unproven.
Limitations of the Evidence
Evidence for barusiban is sparse: only one small IVF trial and one preterm‑labour trial have been published, both showing no clear efficacy. The IVF trial did not report live‑birth outcomes, and the tocolysis study was limited to late‑gestation women. Overall certainty is low, with wide confidence intervals and potential bias in the few available studies. More large, well‑designed randomized trials are needed to clarify effectiveness.
Safety Considerations
Barusiban was well tolerated in the limited trials. The IVF study noted mild to moderate injection‑site reactions but no serious drug‑related events, and neonatal outcomes were comparable to placebo. The preterm‑labour trial reported no safety concerns for mother, fetus, neonate, or infant. Nonetheless, the safety database is small, and rare adverse effects cannot be excluded.
How It Is Administered
Barusiban is delivered as an injectable peptide, either intravenously (as a single bolus in the preterm‑labour study) or subcutaneously (as used in the assisted‑reproduction trial). Formulations are sterile solutions intended for clinical use under controlled conditions.
Routes of Administration
Goals & Uses
- Inhibition of preterm laborObstetric / TocolysisModerate
- Improved tocolytic tolerability vs atosibanSafety / PharmacologyLow
- Preterm labor suppressionObstetricsModerate
- Reduction of uterine contractionsObstetricsModerate
Contraindications
- Hypersensitivity to barusiban or related peptidesAllergyHigh
- Severe fetal distressObstetricHigh
- Intrauterine infection / chorioamnionitisObstetricHigh
- Severe maternal hypertensionCardiovascularModerate
- Placenta previa with active bleedingObstetricHigh
Adverse Effects
- Cardiovascular effects (tachycardia, hypotension)CardiovascularRare
- Injection site reactionsLocalCommon
- HeadacheNeurologicUncommonPain in the head or upper neck
- NauseaGastrointestinalUncommonFeeling of sickness or urge to vomit
- Injection site erythemaLocalCommonRedness at the injection site
Drug Interactions
- OxytocinModerate
- Ergot alkaloids (e.g., ergometrine)Moderate
Population Constraints
- Multiple gestationObstetricRelative
- Pregnant women beyond 34 weeks gestationObstetric TimingRelative
- Gestational age < 24 weeks or > 34 weeksObstetricRelative
- Hepatic or renal impairmentOrgan ImpairmentRelative
Regulatory Status
- European UnionInvestigationalNot authorized for marketing in the European Union
- United StatesInvestigationalNo FDA approval; studied in Phase II trials for preterm labor
- United KingdomInvestigationalNot MHRA-approved; research use only.
Development discontinued after phase II trials; not approved in any jurisdiction.
Evidence & Sources
- Journal ArticleLowHelmer H, et al.2020-01-01T00:00:00.000000Z
- Journal ArticleHighNeumann K, Griesinger G2021-01-01T00:00:00.000000Z
- Journal ArticleModerateWiśniewski K2019-01-01T00:00:00.000000Z
- Journal ArticleHighCraciunas L, et al.2021-01-01T00:00:00.000000Z
- Journal ArticleHighFlenady V, et al.2014-01-01T00:00:00.000000Z
- Journal ArticleModerateThornton S, et al.2009-01-01T00:00:00.000000Z
Frequently Asked Questions
What is the intended clinical use of barusiban?
Barusiban is being investigated as a selective oxytocin‑receptor antagonist to stop premature uterine contractions (tocolysis) and, separately, to reduce uterine activity around embryo transfer in in‑vitro fertilisation cycles. It has not received regulatory approval for any indication.
Has barusiban been shown to prevent preterm birth?
In a randomized trial of women at 34‑35 weeks gestation, a single intravenous dose of barusiban did not reduce uterine contractions nor increase the proportion of women who remained undelivered after 48 hours compared with placebo. Current evidence does not support a clear benefit for preventing preterm birth.
Does barusiban improve pregnancy outcomes in IVF?
One small subcutaneous trial found no definitive effect on clinical pregnancy, and live‑birth data were not reported. A meta‑analysis of oxytocin antagonists (including barusiban) suggested a modest increase in clinical pregnancy rates, but the specific contribution of barusiban remains uncertain.
Is barusiban safe for the fetus?
Placental transfer studies showed limited fetal exposure (5‑11% of maternal levels). Clinical trials reported no serious maternal, fetal, or neonatal adverse events, only mild injection‑site reactions. However, the safety data are limited to a few small studies.
How is barusiban administered?
The peptide is given by injection. Early studies used a single intravenous bolus, while the assisted‑reproduction trial employed subcutaneous administration. Formulations are sterile aqueous solutions intended for use under medical supervision.
What is Barusiban used for?
Barusiban is educationally associated with: Inhibition of preterm labor, Improved tocolytic tolerability vs atosiban, Preterm labor suppression, Reduction of uterine contractions. Educational only — not medical advice.
How is Barusiban administered?
Recorded routes of administration: Intravenous, Subcutaneous.
What are the potential side effects of Barusiban?
Reported adverse effects include: Cardiovascular effects (tachycardia, hypotension), Injection site reactions, Headache, Nausea, Injection site erythema. This list is not exhaustive — consult a qualified clinician.
Who should avoid Barusiban?
Recorded contraindications: Hypersensitivity to barusiban or related peptides, Severe fetal distress, Intrauterine infection / chorioamnionitis, Severe maternal hypertension, Placenta previa with active bleeding. Consult a qualified clinician before use.