Tocolytic (oxytocin receptor antagonist)
Preparation: 7.5 mg/ml (0.9 ml = 6.75 mg bolus vial; 5 ml = 37.5 mg concentrate) · Infusion 0.75 mg/ml (withdraw 10 ml from 100 ml carrier solution, add 2 × 5 ml concentrate = 75 mg)
Tocolysis in threatened preterm birth
- 6.75 mg Step 1 – i.v. bolus over 1 min[108]7.5 mg/ml (0.9 ml = 6.75 mg bolus vial; 5 ml = 37.5 mg concentrate) · = 0.9 ml
- 18 mg/h over 3 h (= 24 ml/h of the 0.75 mg/ml solution) Step 2 – i.v. loading infusion[108]
- 6 mg/h for up to 45 h (= 8 ml/h of the 0.75 mg/ml solution) Step 3 – i.v. maintenance infusion[108]
- Total treatment max. 48 h; total dose max. 330.75 mg Maximum duration/dose[108]
Licensed indication – 24+0 to 33+6 weeks of gestation, regular contractions (≥ 4 in 30 min, each ≥ 30 s), cervical dilatation 1–3 cm (nulliparous women 0–3 cm), effacement ≥ 50 %, normal fetal heart rate, pregnant women ≥ 18 y. Aim – gaining time for induction of fetal lung maturation and transfer to a perinatal centre.
Contraindications
- Gestational age < 24 or > 33 completed weeks
- Premature rupture of membranes > 30 weeks of gestation
- Fetal growth restriction or abnormal fetal heart rate
- Uterine bleeding requiring immediate delivery; placenta praevia, placental abruption
- Severe pre-eclampsia/eclampsia requiring delivery
- Intrauterine fetal death, suspected intra-amniotic infection
- Hypersensitivity to atosiban
Notes
- Well tolerated – common: nausea, headache, dizziness, hot flushes, tachycardia, hypotension, injection-site reaction.
- If contractions recur, the cycle may be repeated (starting with the bolus) (SmPC).
- Multiple pregnancy and gestational age 24–27 weeks – limited data.