Oxytocin Receptor Antagonist (Tocolytic) Pregnancy: Atosiban should only be used when pre-term labour has been diagnosed between 24 and 33 completed weeks of gestation. If the woman is already breast-feeding an earlier child, breast-feeding should be discontinued during treatment (oxytocin release during breast-feeding may augment uterine contractility and counteract tocolysis); small amounts pass into breast milk.

Atosiban (Tocolysis)

Brand names: Tractocile

Atosiban is an oxytocin receptor antagonist used as a tocolytic to delay imminent preterm birth in women in established preterm labour.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Three successive intravenous stages: (1) initial bolus 6.75 mg (0.9 mL of the 6.75 mg/0.9 mL solution for injection) given over 1 minute; (2) loading infusion 300 micrograms/min (24 mL/hour of the 37.5 mg/5 mL concentrate, diluted) for 3 hours = 54 mg; (3) subsequent infusion 100 micrograms/min (8 mL/hour) for up to 45 hours = up to 270 mg

Route: Intravenous — bolus injection followed by continuous infusion

Frequency: Single continuous course: bolus once, immediately followed by the 3-hour loading infusion, then the lower-rate infusion for up to 45 hours

Max: Duration of treatment should not exceed 48 hours. The total dose given during a full course should preferably not exceed 330.75 mg of atosiban.

Source: UK SPC for Atosiban 37.5 mg/5 mL concentrate for solution for infusion (§4.2). Treatment should be initiated and maintained by a physician experienced in the treatment of pre-term labour. Intravenous therapy with the initial bolus injection should be started as soon as possible after diagnosis of pre-term labour; once the bolus has been injected, proceed with the infusion. Infusion rates and units are stated exactly as in the SPC (300 micrograms/min = 24 mL/hour; 100 micrograms/min = 8 mL/hour). If uterine contractions persist during treatment, alternative therapy should be considered. Re-treatment: if needed, it should also commence with a 6.75 mg bolus injection followed by the infusion; limited clinical experience with multiple re-treatments, up to 3 re-treatments. Licensed gestational window: pre-term labour diagnosed between 24 and 33 completed weeks of gestation. Hepatic impairment: use with caution (no experience). Paediatric: safety and efficacy in pregnant women aged less than 18 years have not been established; no data available (§4.2). Monitoring of uterine contractions and fetal heart rate during administration should be considered, and blood loss after delivery should be monitored (theoretical risk of postpartum bleeding from uterine relaxation).

Dose adjustments

Renal

No experience in patients with impaired renal function. Renal impairment is not likely to warrant a dose adjustment, since only a small extent of atosiban is excreted in the urine.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Gestational age below 24 or over 33 completed weeks
Premature rupture of the membranes > 30 weeks of gestation
Abnormal foetal heart rate
Antepartum uterine haemorrhage requiring immediate delivery
Eclampsia and severe pre-eclampsia requiring delivery
Intrauterine foetal death or suspected intrauterine infection
Placenta praevia or abruptio placentae
Any other condition of the mother or foetus in which continuation of pregnancy is hazardous
Hypersensitivity to the active substance or to any of the excipients

Side effects

Nausea (very common — 14%)
Headache and dizziness (common)
Tachycardia, hypotension, hot flush (common)
Hyperglycaemia (common)
Vomiting, insomnia, pruritus, rash, injection site reaction (common)
Uterine haemorrhage and uterine atony (uncommon); allergic reaction (uncommon); pyrexia (rare). Post-marketing: dyspnoea and pulmonary oedema

Interactions

Unlikely to be involved in cytochrome P450 mediated drug-drug interactions — atosiban is not a CYP substrate and does not inhibit CYP enzymes (§4.5)
Interaction studies with labetalol and betamethasone in healthy female volunteers found no clinically relevant interaction
Other medicinal products with tocolytic activity (calcium channel blockers, beta-mimetics) — caution: increased risk of pulmonary oedema, particularly in multiple pregnancy (§4.4)

Clinical monograph

How it works

It competitively blocks oxytocin receptors on the myometrium, reducing the frequency and intensity of uterine contractions.

Prescribing in practice

It is intended only to provide short-term delay of preterm delivery, typically to allow time for antenatal corticosteroids and in-utero transfer, not to treat the underlying cause.
It is contraindicated where prolonging the pregnancy would be hazardous, such as in suspected intrauterine infection, antepartum haemorrhage requiring delivery, eclampsia, or fetal compromise.
It is given by intravenous infusion under specialist supervision following a defined initial bolus and maintenance regimen.

Monitoring

Monitor uterine contractions, fetal wellbeing, and maternal blood loss during and after the infusion.

Counselling the patient

Explain that this medicine aims to delay your labour for a short period to allow other treatments to protect the baby.
Report any increase in bleeding, abdominal pain, or reduced fetal movements to staff.
It is given as a drip in hospital and you will be closely monitored throughout.

Evidence & guidelines

Atosiban and other tocolytics are used, as reflected in NICE guidance on preterm labour and birth, mainly to enable corticosteroid administration and transfer rather than to improve neonatal outcomes directly.

Reference: NICE NG25 Preterm Labour and Birth; RCOG Tocolysis Guideline; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Myasthenia Gravis Activities of Daily Living (MG-ADL) Scale · Neuromuscular

Pathways