Intramuscular Treatment and prophylaxis of postpartum haemorrhage
Adult: Available preparation:
Each 1 mL solution contains oxytocin 5 IU and ergometrine maleate 500 mcg
1 mL after placental expulsion or in the occurrence of bleeding. Doses may be repeated after ≤2 hours. Max: 3mL daily.
Intramuscular Active management of the third stage of labour
Adult: Available preparation:
Each 1 mL solution contains oxytocin 5 IU and ergometrine maleate 500 mcg
Administer 1 mL after delivery of the anterior shoulder or immediately after delivery of the infant.
Renal Impairment
Severe: Contraindicated.
Hepatic Impairment
Severe: Contraindicated.
Contraindications
Labour induction, 1st or 2nd stage of labour prior to the delivery of anterior shoulder, primary or secondary uterine inertia, severe cardiac disease, severe hypertension, pre-eclampsia, eclampsia, occlusive vascular disease, sepsis. Severe renal and hepatic impairment. Pregnancy.
Special Precautions
Women with mild to moderate hypertension, CV disease (e.g. coronary artery disease), long QT syndrome, Raynaud’s phenomenon. Mild to moderate renal and hepatic impairment. In cases of breech and other abnormal presentations, this medicine should not be given until after delivery of the child or in multiple births until the last child has been delivered.
Symptoms: Ergometrine: Nausea, vomiting, respiratory depression, hypotension or hypertension, vasospastic reactions, convulsion, coma. Management: Symptomatic treatment. Activated charcoal may be given within 1 hour of ingestion of a toxic dose. Alternatively, may consider gastric lavage within 1 hour of ingestion of a potentially life-threatening overdose. Maintain adequate circulation to prevent onset of gangrene. Administer vasodilators (e.g. Na nitroprusside) to treat severe arterial vasospasms. Give heparin and dextran 40 to reduce the risk of thrombosis. To treat severe ischaemic pain, administer analgesics.
Drug Interactions
Increased vasopressor action of vasoconstrictors and sympathomimetics. Enhanced uterine action of prostaglandins and vice versa. Diminished uterotonic effect with inhalation anaesthetics (e.g. halothane, cyclopropane, isoflurane, desflurane, sevoflurane).
Oxytocin: Increased risk of arrhythmia with drugs that prolong QT interval.
Ergometrine: Reduced therapeutic effect with CYP3A4 inducers. Increased risk of ergot toxicity with CYP3A4 inhibitors (e.g. erythromycin, clarithromycin, ritonavir, indinavir, nelfinavir, delavirdine, ketoconazole, itraconazole, voriconazole, cimetidine). Enhance vasopressor effects of triptans. Potentiated vasoconstrictive action with β-blockers. Diminished therapeutic efficacy of glyceryl trinitrate and other antianginal drugs.
Food Interaction
Increased ergometrine plasma concentration with grapefruit.
Action
Description: Oxytocin and ergometrine acts on the uterus via different but complimentary mechanisms.
Oxytocin, a cyclic nonapeptide, activates G-protein-coupled receptors at the uterus which causes an increase in intracellular Ca levels in uterine myofibrils, thus promoting uterine contractions.
Ergometrine, an ergot alkaloid, acts on the 5-HT2 and α-adrenergic receptors to produce a sustained tonic uterine action.
Synonym: ergonovine. Onset: Oxytocin: IM: 3-5 minutes.
Ergometrine: 2-5 minutes. Duration: Oxytocin: 2-3 hours.
Ergometrine: ≥3 hours. Pharmacokinetics: Absorption: Rapidly absorbed after IM administration. Distribution: Crosses placenta, enters breast milk. Metabolism: Oxytocin: Metabolised in the liver and kidneys.
Ergometrine: Metabolised in the liver. Excretion: Via urine as unchanged drug.
Oxytocin: Elimination half-life: 3-20 minutes.
Ergometrine: Elimination half-life: 30-120 minutes.
Chemical Structure
Oxytocin Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 439302, Oxytocin. https://pubchem.ncbi.nlm.nih.gov/compound/Oxytocin. Accessed Nov. 25, 2020.
Ergometrine Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 443884, Ergometrine. https://pubchem.ncbi.nlm.nih.gov/compound/Ergometrine. Accessed June 28, 2022.
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.
References
Anon. Ergonovine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/10/2020.Anon. Oxytocin and Ergometrine Maleate. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/10/2020.Anon. Oxytocin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/10/2020.Buckingham R (ed). Ergometrine Maleate. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/10/2020.Buckingham R (ed). Oxytocin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/10/2020.Joint Formulary Committee. Ergometrine with Oxytocin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/10/2020.Syntometrine (Rotexmedica GmbH). MIMS Singapore. http://www.mims.com/singapore. Accessed 01/10/2020.Syntometrine 500 micrograms/5 IU Solution for Injection (Alliance Pharmaceuticals Ltd). MHRA. https://products.mhra.gov.uk/. Accessed 01/10/2020.
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