Composition: Atosiban (as acetate) 7.5mg/ml.
Presentation: Solution for injection (6.75mg/vial); concentrate for solution for infusion (37.5mg/vial).
Storage and stability: Store at 2-8C in original container.
Action: Competitive antagonist of human oxytocin at receptor level.
Indications: Delay of imminent preterm birth in pregnant women with: regular uterine contractions of at least 30 seconds duration at a rate of four or more per 30 minutes, a cervical dilation of 1-3cm (0-3 for nulliparas) and effacement of 50 per cent or more, age 18 years and over, a gestational age from 24 until 33 completed weeks, and a normal foetal heart rate.
Contraindications: Gestational age below 24 or over 33 completed weeks; premature rupture of membranes at over 30 weeks of gestation; intrauterine growth retardation and abnormal foetal heart rate; antepartum uterine haemorrhage requiring immediate delivery; eclampsia and severe pre-eclampsia requiring delivery; intrauterine foetal death; suspected intrauterine infection; placenta praevia; abruptio placenta; any other conditions of the mother or foetus, in which continuation of pregnancy is hazardous; known hypersensitivity to active substance or excipients.
Dosage and administration: Administer in three successive stages. An initial bolus dose (6.75mg), using Tractocile 7.5mg/ml solution for injection, immediately followed by a continuous high dose infusion (loading infusion 300µg/min) of Tractocile 7.5mg/ml concentrate for solution for infusion over three hours, followed by a lower dose of Tractocile 7.5mg/ml concentrate for solution for infusion (subsequent infusion 100µg/min) for up to 45 hours (see table in SPC). Duration of treatment should not exceed 48 hours. The total dose given during a full course of therapy should preferably not exceed 330mg. See SPC for instructions on preparation of the intravenous infusion solution.
Intravenous therapy using the initial bolus injection should be started as soon as possible after diagnosis of preterm labour. Alternative therapy should be considered in the case of persistent uterine contractions.
Renal and liver insufficiency, no data available regarding the need for dose adjustments.
Overdosage: Few cases reported which occurred without any specific signs or symptoms. There is no known specific treatment in case of an overdose.
Precautions: When 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. There is limited experience of use in multiple pregnancies or the gestational age group between 24 and 27 weeks and therefore the benefit in these subgroups is uncertain. Monitoring of uterine contractions and foetal heart rate during administration and in the case of persistent uterine contractions should be considered. Blood loss after delivery should be monitored.
Drug interactions: No interaction studies have been performed.
Side effects: Very common (incidence greater than 10 per cent), nausea; common (1-10 per cent), headache, dizziness, hot flushes, vomiting, tachycardia, hypotension, injection site reaction, hyperglycaemia; uncommon (0.1-1 per cent), fever, insomnia, pruritus, rash. For the newborn, clinical trials did not reveal any specific undesirable effects of atosiban.
Net price: Solution for injection (6.75mg vial), £20; concentrate for solution for infusion (37.5mg vial), £55.
Supplier: Ferring Pharmaceuticals Ltd, The Courtyard, Waterside Drive, Langley, Berkshire SL3 6EZ. Tel 01753 214800, fax 01753 214801.
Legal class: POM.