VIATOCINON

What it is

VIATOCINON is oxytocin solution for injection. It is available in ampoules containing 10 IU in 1 mL. The injection is a sterile aqueous solution containing synthetic oxytocin. Oxytocin stimulates the smooth muscle of the uterus, producing rhythmic contractions, particularly towards the end of pregnancy, during labour, after delivery and in the puerperium, at times when the number of specific oxytocin receptors in the myometrium is increased.

Approved indications

— Induction of labour. — Inadequate uterine effort. — Management of third stage of labour. — Post-partum haemorrhage.

Dosing overview

VIATOCINON is intended for intravenous administration. Dosing varies by indication.

For induction or augmentation of labour, oxytocin should only be administered as an intravenous infusion, preferably by means of a variable speed infusion pump, or by drip infusion, and should not be administered by subcutaneous, intramuscular or intravenous bolus injection.

Key safety warnings

Administration of oxytocin at excessive doses results in uterine over-stimulation which may cause foetal distress, asphyxia and death, or may lead to hypertonicity, tetanic contractions or rupture of the uterus. The frequency and duration of contractions and foetal heart rate must be carefully monitored during oxytocin administration, the latter preferably by electronic means, and the infusion must be discontinued immediately in the event of uterine hyperactivity, foetal distress or foetal heart abnormalities. Rapid intravenous bolus injection of oxytocin at high doses should be avoided, as it may cause acute short-lasting hypotension accompanied by flushing and reflex tachycardia, and these rapid haemodynamic changes may result in myocardial ischaemia, particularly in patients with pre-existing cardiovascular disease. Water intoxication associated with maternal and neonatal hyponatraemia, which is potentially fatal, has been reported in cases where high doses of oxytocin have been administered together with large amounts of electrolyte-free fluid over a prolonged period of time, as the weak anti-diuretic activity of oxytocin may contribute, but the major cause is the use of large amounts of electrolyte-free fluids. There have been reports of anaphylaxis following administration of oxytocin in women with a known latex allergy, as latex allergy/intolerance may be an important predisposing risk factor for anaphylaxis following oxytocin administration due to structural homology between oxytocin and latex.

Contraindications

Foetal distress and any condition in which, for foetal or maternal reasons, spontaneous labour is inadvisable and/or vaginal delivery is contraindicated, such as cephalo-pelvic disproportion, abnormal presentation, cord presentation or prolapse, excessive distension or impaired resistance of the uterus to rupture (for example, multiple pregnancy, polyhydramnios), parity greater than 4, elderly multiparae, grand multiparity, and in the presence of uterine scar resulting from major surgery including previous Caesarean section or other surgery involving the uterus. Severe toxaemia, predisposition to amniotic fluid embolism (foetal death-in-utero, abruptio placentae), hypertonic contractions, placenta praevia and vasa praevia, placental abruption. Hypersensitivity to oxytocin or to any of the excipients in the formulation. Oxytocin must not be administered within 6 hours after vaginal prostaglandins have been given.

Regulatory history

VIATOCINON oxytocin 10 IU/1 mL injection ampoule was first listed on the ARTG on 11 March 2011.