Oxytocin + Ergometrine

Severe: Contraindicated.

Severe: Contraindicated.

Labour induction, 1st or 2nd stage of labour prior to the delivery of the anterior shoulder; primary or secondary uterine inertia; severe cardiac disorders, severe hypertension, pre-eclampsia, eclampsia; occlusive vascular disease, sepsis. Severe renal and hepatic impairment. Pregnancy.

Patient with mild to moderate hypertension, cardiac disorder, coronary artery disease, arrhythmia, risk factors for torsades de pointes (e.g. history of long QT syndrome); Raynaud's phenomenon, respiratory disease, chronic anaemia. In case of breech and other abnormal presentations, do not administer until after delivery of the child, or in multiple births, until the last child has been delivered. Mild to moderate renal and hepatic impairment. Avoid repeated use in lactating women.

Significant: Anaphylaxis (in patients with latex allergy).
Cardiac disorders: Bradycardia, chest pain, cardiac arrhythmias, MI, coronary arteriospasm.
Gastrointestinal disorders: Vomiting, nausea, abdominal pain.
Nervous system disorders: Headache, dizziness.
Skin and subcutaneous tissue disorders: Rash, angioedema.
Vascular disorders: Hypertension.

Monitor blood pressure and pulse rate.

Ergometrine: Symptoms: Nausea, vomiting, hypertension, hypotension, convulsions, vasospastic reactions, respiratory depression and coma. Management: Maintain adequate circulation to prevent the onset of gangrene. Administer vasodilators (e.g. Na nitroprusside) to treat severe arterial vasospasms. Heparin and dextran 40 may also be administered to reduce the risk of thrombosis. For severe ischaemic pain, analgesics may be necessary.

May diminish uterotonic effect with inhalation anaesthetics (e.g. halothane, cyclopropane, isoflurane, desflurane, sevoflurane). May enhance the vasopressor action of vasoconstrictors and sympathomimetics. May potentiate the uterine action of prostaglandins and analogues.
Oxytocin: Increased risk of torsades de pointes with drugs that prolong the QT interval.
Ergometrine: May elevate serum concentration and increase the risk of ergotism with strong CYP3A4 inhibitors (e.g. erythromycin, clarithromycin, ritonavir, indinavir, ketoconazole, itraconazole, quinolones). May decrease therapeutic effect with CYP3A4 inducers (e.g. rifampicin, nevirapine). Additive vasopressor effects with triptans (e.g. sumatriptan, zolmitriptan). May enhance vasoconstricting effect with β-blockers. Increased risk of severe and persistent spasm of major arteries with other ergot alkaloids (e.g. methysergide) and other ergot derivatives. May decrease the effects of glyceryl trinitrate and other antianginal agents.

Description:
Mechanism of Action: Oxytocin is a cyclic nonapeptide that activates the receptors in the uterus which causes the release of intracellular Ca and local prostaglandin production, thus stimulating uterine contractions.
Ergometrine, an ergot alkaloid, acts on the myometrial 5-HT₂ and α-adrenergic receptors to produce sustained tonic uterine contractions
Synonym(s): Ergometrine: Ergonovine.
Onset: Oxytocin: 3-5 minutes (IM); approx 1 minute (IV).
Ergometrine: 2-5 minutes (IM); immediate (IV).
Duration: Oxytocin: 2-3 hours (IM); 1 hour (IV).
Ergometrine: ≥3 hours (IM); approx 45 minutes (IV).
Pharmacokinetics:
Absorption: Rapidly absorbed from the injection site.
Distribution: Crosses the placenta.
Oxytocin: Enters breast milk in small amounts.
Ergometrine: Enters breast milk.
Metabolism: Oxytocin: Metabolised in the liver and kidneys.
Ergometrine: Metabolised mainly in the liver via hydroxylation, glucuronic acid conjugation and possibly N-demethylation.
Excretion: Oxytocin: Via urine (<1% as unchanged drug). Elimination half-life: 3-20 minutes.
Ergometrine: Via urine as unchanged drug. Elimination half-life: 30-120 minutes.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 439302, Oxytocin. https://pubchem.ncbi.nlm.nih.gov/compound/Oxytocin. Accessed May 28, 2025.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 443884, Ergonovine. https://pubchem.ncbi.nlm.nih.gov/compound/Ergonovine. Accessed May 28, 2025.

Store between 2-8°C or may store up to 25°C for 2 months. Do not freeze. Protect from light.

Drugs Acting on the Uterus

G02AC - Ergot alkaloids and oxytocin incl. analogues, in combination ; Used to induce abortion or augment labour and to minimize blood loss from the placental site.

Brayfield A, Cadart C (eds). Ergometrine Maleate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/05/2025.

Brayfield A, Cadart C (eds). Oxytocin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/05/2025.

Ergometrine Maleate [Ergonovine]. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 08/05/2025.

Joint Formulary Committee. Ergometrine with Oxytocin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 08/05/2025.

Max Health Limited. Syntometrine Solution for Injection data sheet 31 March 2022. Medsafe. http://www.medsafe.govt.nz. Accessed 08/05/2025.

Oxytocin and Ergometrine Maleate [Ergonovine]. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 08/05/2025.

Oxytocin. UpToDate Lexidrug, Lexi-Drugs Multinational Online. Waltham, MA. UpToDate, Inc. https://online.lexi.com. Accessed 08/05/2025.

Syntometrine 500 micrograms/5 IU Solution for Injection (Alliance Pharmaceuticals Ltd). MHRA. https://products.mhra.gov.uk. Accessed 08/05/2025.

Syntometrine Injection 500 micrograms/5 IU/1 mL Ampoule (Rigel Pharma Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 08/05/2025.