Reproductive · In Clinical Trials
Atosiban
No lawful US pathway
01 · Overview
A competitive oxytocin/vasopressin V1a receptor antagonist used outside the US as a tocolytic agent to delay preterm labor. Atosiban blocks oxytocin-mediated myometrial contractions and causes fewer maternal cardiovascular side effects than beta-adrenergic tocolytics (PMID 11236112).
The peptide is given intravenously as a bolus followed by an infusion for up to 48 hours.
02 · Research summary & key findings
Registered in Europe and other countries for threatened preterm birth but not FDA-approved in the US. A Cochrane review found no superiority over placebo, betamimetics, or nifedipine for pregnancy prolongation or neonatal outcomes, but fewer maternal adverse effects than betamimetics or calcium channel blockers (Flenady et al., Cochrane Review, 2014) (PMID 24903678). In a large trial versus beta-agonists, delivery was delayed by 48 hours in a similar proportion of women (88.1% versus 88.9%), with far fewer maternal cardiovascular events on atosiban (8.3% versus 81.2%) (PMID 11236112). The APOSTEL 8 trial found atosiban did not improve neonatal outcomes compared with placebo at 30-34 weeks of gestation (PMID 40049187).
03 · Regulatory status
Atosiban is currently undergoing clinical trials. It is not yet FDA-approved and is available only through clinical research settings or investigational protocols.
No lawful pathway today
Atosiban is not FDA-approved and does not currently have a lawful prescription or compounding pathway in the United States, so we do not sell it and will not book a consultation for it. That can change: in 2026 FDA began reviewing several peptides for compounding. If you are working on the goal it is studied for, a licensed clinician can tell you what is lawfully available, which may be something else.
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Atosiban is still in clinical trials, is not FDA-approved, and has no lawful US compounding pathway, so we do not offer it and no clinician we work with will prescribe it. Products sold online as “research chemicals” are not made or tested to the standards required of medicines. If you are working on hormone optimization, a licensed clinician can tell you at a free consultation whether an FDA-approved or lawfully compounded treatment fits you, or whether nothing does.
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04 · Administration routes
- Intravenous
References
- [1]Effectiveness and safety of the oxytocin antagonist atosiban versus beta-adrenergic agonists in the treatment of preterm labour. The Worldwide Atosiban versus Beta-agonists Study Group BJOG, 2001. PMID 11236112
- [2]Oxytocin receptor antagonists for inhibiting preterm labour Cochrane Database Syst Rev, 2014. PMID 24903678
- [3]Atosiban versus placebo for threatened preterm birth (APOSTEL 8): a multicentre, randomised controlled trial Lancet, 2025. PMID 40049187
Primary literature
- PubMed: "Atosiban"
Peer-reviewed literature indexed by the National Library of Medicine.
- ClinicalTrials.gov: "Atosiban"
Registered interventional and observational studies, including status and phase.
- PubChem: "Atosiban"
Chemical structure, molecular properties, and bioactivity data.
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