oxytocin: clinical use

Prescribing considerations

• Use only under hospital conditions with qualified obstetric supervision.
• Use an infusion pump or controlled intravenous infusion; never administer this product by rapid intravenous bolus.
• Apply particular caution with cardiovascular disease, long-QT syndrome, renal impairment, previous lower-segment caesarean section or risk factors for disseminated intravascular coagulation.
• Prevent selection errors between antepartum and postpartum oxytocin preparations through clear storage, prescribing and checking processes.
• Consider fluid restriction, fluid-balance recording and electrolyte-containing diluent where prolonged administration or fluid overload is a concern.

Contraindications and cautions

• Hypersensitivity to oxytocin or an excipient.
• Hypertonic contractions, mechanical obstruction to delivery or fetal distress.
• Circumstances in which labour or vaginal delivery is contraindicated, including significant cephalopelvic disproportion, malpresentation, placenta or vasa praevia, placental abruption, or cord presentation or prolapse.
• Marked uterine overdistension or impaired resistance to rupture, including relevant multiple pregnancy, polyhydramnios, grand multiparity or a scar from major uterine surgery.
• Prolonged use in oxytocin-resistant uterine inertia, severe pre-eclamptic toxaemia or severe cardiovascular disease.
• Use too soon after vaginal prostaglandins.

Monitoring

• Continuously assess contraction frequency, strength and duration and the fetal heart rate during labour.
• Stop the infusion immediately for uterine hyperactivity or fetal distress and manage according to the clinical situation.
• Monitor pulse and blood pressure, particularly where cardiovascular risk is present.
• Monitor fluid balance and check serum electrolytes if water retention or hyponatraemia is suspected.
• Remain alert for anaphylaxis, especially in people with latex allergy.

Clinical pharmacology

Synthetic oxytocin is identical to the natural peptide hormone. It activates G-protein-coupled oxytocin receptors, releases intracellular calcium and contracts uterine smooth muscle; it also has weak antidiuretic activity and a short plasma half-life.

Formulation and product differences

• The selected product is a clear, colourless solution for intravenous infusion supplied in single-use glass ampoules; it is not an oral preparation.
• It contains sodium and must not be infused through the same apparatus as blood or plasma.
• It requires refrigerated, light-protected storage, with limited product-specific room-temperature storage permitted.

Solution for infusion

Route: Intravenous

Strengths: 5 units/mL, 10 units/mL