Oxytocin is a hormone given by injection (usually in hospital) that makes the uterus contract. It is used to induce or augment labour and, after birth, to prevent and treat uterine bleeding.
Also known as: Pitocin, Synthocinol
Oxytocin plus misoprostol for labour induction or pregnancy termination can cause uterine hyperstimulation, with risk of uterine rupture.
Both are potent uterotonics; the combination is not approved in the labels (Cytotec contraindicates combination with oxytocin/prostaglandins).
Contraction frequency and intensity, fetal distress, continuous uterine pain.
More than 5 contractions per 10 min, uterine pain between contractions, fetal heart decelerations.
Use only in specialised obstetric protocols with time-separated dosing and continuous monitoring of contractions and fetal status.
DailyMed — Cytotec (misoprostol) label, Warnings (contraindication with oxytocin/prostaglandins) and Pitocin (oxytocin): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=52a82e45-afc5-47d0-a77f-a225609e2f6b
No documented food or drink interactions.
Oxytocin has weak antidiuretic and vasodilatory activity but may cause hypotension/tachycardia; obstetric monitoring mandatory.
Diluted infusion with continuous CTG and blood pressure monitoring.
Prontuário Terapêutico INFARMED, 7.2 (oxytocin — continuous obstetric monitoring, CTG).
Oxytocin is the endogenous birth hormone; synthetic oxytocin is the first-line uterotonic for induction/augmentation of labour and prevention/treatment of postpartum haemorrhage — standard obstetric practice in all hospitals. Annex 1 records the entry with a note on high doses at term; risks (neonatal hyperbilirubinaemia, hyponatraemia with prolonged infusion) are known and monitored.
Standard obstetric use (induction, labour augmentation, PPH); administer with maternal and fetal cardiotocographic monitoring; avoid prolonged high doses at term (fetal hyponatraemia).
Oxytocin is destroyed by plasma oxytocinase; little passes into milk and there are no reports of adverse effects in infants at obstetric doses — compatible.
Prontuário Terapêutico INFARMED — Annex 1: "Oxytocin" (l. 41209); 7.2.1 (Oxytocics). EMC-UK (MHRA) — Oxytocin SmPC (Syntocinon).
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
First-line uterotonic hormone for prevention and treatment of postpartum haemorrhage and labour induction; continuously adjustable infusion thanks to its very short half-life.
Binds Gq-coupled oxytocin receptors in the myometrium, activating phospholipase C → IP3 → calcium release from the sarcoplasmic reticulum and voltage-dependent influx: increased uterine contractility, frequency and tone. Progressive receptor sensitisation throughout gestation (potentiated by oestrogens and prostaglandins). At high pharmacological doses, activates renal V2 receptors (antidiuretic effect).
IV: immediate onset, dose-dependent action; IM: onset 3–5 min, duration 30–60 min. Nil oral bioavailability (proteolytic degradation); parenteral use only.
Degradation by plasma and hepatic oxytocinase (cis-trans isomerisation and deamidation); < 1% excreted unchanged in urine. No relevant CYP metabolism — minimal pharmacokinetic interactions.
3–5 min (IV); apparent 20–40 min by IM due to continuous depot absorption.
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
