atosiban acetate: clinical use

Prescribing considerations

• Confirm diagnosed imminent preterm birth and that all licensed maternal, cervical, gestational and fetal criteria are met.
• Treatment must be initiated and maintained by a physician experienced in managing preterm labour.
• Balance the benefit of delaying delivery against infection risk when membrane rupture cannot be excluded.
• Experience is limited in multiple pregnancy, early parts of the licensed gestational window, patients under 18 and repeated treatment.
• Use cautiously with hepatic impairment; experience in hepatic or renal impairment is limited.

Contraindications and cautions

• Gestation outside the licensed range.
• Premature rupture of membranes after 30 weeks.
• Abnormal fetal heart rate, intrauterine fetal death or suspected intrauterine infection.
• Placenta praevia, placental abruption or antepartum bleeding requiring immediate delivery.
• Eclampsia or severe pre-eclampsia requiring delivery.
• Any maternal or fetal condition in which continuing pregnancy is hazardous.
• Hypersensitivity to atosiban or an excipient.

Monitoring

• Monitor uterine contractions and fetal heart rate, particularly if contractions persist.
• Observe for breathlessness or pulmonary oedema, especially with multiple pregnancy or concurrent tocolytics.
• Monitor blood loss after delivery because oxytocin antagonism could theoretically promote uterine relaxation.
• Reassess management if contractions persist or labour progresses.

Clinical pharmacology

Atosiban is a synthetic peptide that competitively antagonises oxytocin receptors and also binds vasopressin receptors. It reduces uterine tone and contraction frequency, crosses the placenta and declines rapidly in plasma after infusion ends. Cytochrome P450-mediated interactions are unlikely.

Formulation and product differences

• The solution for injection is used for initial intravenous administration and must be used immediately after opening.
• The concentrate for infusion requires dilution in a compatible intravenous fluid and controlled infusion equipment.
• Both selected formulations are clear, colourless parenteral solutions containing mannitol, hydrochloric acid and water for injections.

Solution for infusion

Route: Intravenous

Strengths: 7.5 mg/mL, 37.5 mg/5 mL

Injection

Route: Parenteral

Strengths: 6.75 mg/0.9 mL, 7.5 mg/mL