Atosiban

Indications

Atosiban is used for: Premature labour, Atosiban is indicated for use in delaying imminent pre-term birth in pregnant adult women with: regular uterine contractions of at least 30 s duration at a rate of at least 4 per 30 min a cervical dilation of 1-3cm (0-3cm for nulliparas) and effacement of at least 50% a gestational age of 24-33 weeks a normal fetal heart rate

Adult Dose

Intravenous Premature labour Adult: Initially, 6.75 mg bolus (as 7.5 mg/mL soln) over 1 min, immediately followed by continuous infusion (as 0.75 mg/mL soln) of 0.3 mg/min for 3 hr, then 0.1 mg/min for up to 45 hr. Total duration: <48 hr. Max: 330.75 mg. Administered intravenously in three successive stages: Step 1: 0.9 ml intravenous initial bolus over 1 minute (Atosiban dose: 6.75 mg) Step2: 3 hours intravenous loading infusion 24 ml/hour (Atosiban dose: 18 mg/hour) Step3: subsequent intravenous infusion 8 ml/hour (Atosiban dose: 6 mg/hour). The duration of the treatment should not exceed 48 hours.

Child Dose

Renal Dose

Administration

Preparation of the intravenous infusion solution: For intravenous infusion, Atosiban 37.5 concentrate for solution for infusion should be diluted in one of the following solutions: • 0.9% w/v NaCl • Ringer's lactate solution • 5% w/v glucose solution Withdraw 10 ml solution from a 100 ml infusion bag and discard. Replace it by two 5 ml vials of Atosiban 37.5.

Contra Indications

• Gestational age below 24 or over 33 completed weeks • Premature rupture of the membranes >30 weeks of gestation • Intrauterine growth retardation and abnormal fetal heart rate • Antepartum uterine haemorrhage requiring immediate delivery • Eclampsia and severe pre-eclampsia requiring delivery • Intrauterine fetal death • Suspected intrauterine infection • Placenta praevia • Abruptio placenta • Any other conditions of the mother or fetus, in which continuation of pregnancy is hazardous • Known hypersensitivity to the active substance or any of the excipients.

Precautions

When Atosiban is used in patients in whom premature rupture of membranes cannot be excluded, the benefits of delaying delivery should be balanced against the potential risk of chorioamnionitis. Atosiban has not been used in patients with an abnormal placental site. There is only limited clinical experience in the use of Atosiban in multiple pregnancies or the gestational age group between 24 and 27 weeks, because of the small number of patients treated. Retreatment with Atosiban is possible, but there is only limited clinical experience available with multiple re-treatments, up to 3 retreatments. In case of intrauterine growth retardation, the decision to continue or reinitiate the administration of Atosiban depends on the assessment of fetal maturity. Monitoring of uterine contractions and fetal heart rate during administration of Atosiban and in case of persistent uterine contractions should be considered. As an antagonist of oxytocin, Atosiban may theoretically facilitate uterine

Pregnancy-Lactation

Pregnancy Atosiban should only be used when pre-term labour has been diagnosed between 24 and 33 completed weeks of gestation. Breast-feeding If during pregnancy the woman is already breast-feeding an earlier child, then breast-feeding should be discontinued during treatment with atosiban, since the release of oxytocin during breast-feeding may augment uterine contractility, and may counteract the effect of tocolytic therapy. In atosiban clinical trials no effects were observed on breast-feeding. Small amounts of atosiban have been shown to pass from plasma into the breast milk of breast-feeding women. Fertility Embryo-fetal toxicity studies have not shown toxic effects of atosiban. No studies were performed that covered fertility and early embryonic development

Interactions

Increased risk of pulmonary oedema w/ other tocolytic drugs (e.g. Ca channel blockers, betamimetics)

Adverse Effects

Side effects of Atosiban : Nausea, vomiting, headache, dizziness, flushes, tachycardia, hypotension, hyperglycaemia, inj site reactions; insomnia, pruritus, rash, pyrexia. Rarely, uterine haemorrhage and atony.

Mechanism of Action

Atosiban, a synthetic oxytocin peptide analogue, is a competitive antagonist of oxytocin receptors. It suppresses uterine contractions by decreasing its frequency and the tone of uterine musculature. Additionally, it inhibits the effect of vasopressin.