Oxytocin

Registered South African indications:

• Induction of labour
• Augmentation of labour
• Postpartum haemorrhage
• Uterine atony
• Adjunct therapy for management of miscarriage

Contraindications

• Hypersensitivity to the active ingredient or any of its excipients 
• Hypertonic uterine contractions
• Foetal distress when delivery is not imminent
• Any conditions where spontaneous labour is inadvisable or vaginal delivery is contraindicated, including:
  • Significant cephalopelvic disproportion
  • Foetal malpresentation
  • Placenta praevia and vasa praevia
  • Placental abruption
  • Cord presentation or prolapse
  • Overdistension or impaired resistance of the uterus to rupture, such as in multiple pregnancy
  • Polyhydramnios
  • Grand multiparity
  • Presence of uterine scars from major surgery, including classical caesarean section

Cautions

• Latex allergy
• Pregnancy
• Breastfeeding
• Renal impairment 
• Hepatic impairment
• Elderly
• Cardiovascular disease 
• QT prolongation
• Intrauterine death
• Borderline cephalopelvic disproportion
• Secondary uterine inertia
• Pregnancy-induced hypertension 
• Patients above 35yrs
• History of lower-uterine-segment caesarean section
• Risk factors for disseminated intravascular coagulation (DIC)

Forms avail. in SA and covered in this monograph: inj

Induction of labour - cervix favourable
Augmentation of labour

• IV infusion: Initial: 1-4 milliunits/min; Titrate by 1-2 milliunits/min at intervals of 30min until labour established/adequate contractions; Max infusion rate: 20 milliunits/min

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See additional prescribing points for administration directions

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In the event of uterine hyperactivity and/or fetal distress, the infusion must be discontinued immediately

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Infusion rates up to 6 milliunits/minute provide oxytocin levels similar to those with spontaneous labour; rates >9 to 10 milliunits/minute are rarely required

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Prevention of uterine atony at caesarean section

• IV: 5 IU, infused over 5min immediately after delivery

Miscarriage (gestation 13-22 weeks) - cervical dilation present
Septic miscarriage

• IV: 20 IU/1L diluent infused at 40 milliunits/min

Prevention of postpartum haemorrhage

Oxytocin not used to induce or augment labour

• IM: 10 IU after delivery of the baby

Oxytocin used to induce or augment labour

• IV: Increase infusion rate during 3rd stage of labour and for the next few hours thereafter

Treatment of postpartum haemorrhage

• IM: 5 IU, immediately as a single dose

OR

• IV: 20 IU/1L diluent infused at 250ml/hr (80 milliunits/min)

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Diluent: normal saline or 5% dextrose solution

Not established for use in children

Pregnancy

• Caution
• Animal reproduction studies have not been conducted with oxytocin. Based on the wide experience with oxytocin and its chemical structure and pharmacological properties, it is not expected to present a risk of foetal abnormalities when used as indicated

Breastfeeding

• Caution
• Oxytocin may be found in small quantities in mother's breast milk. However, oxytocin is not expected to cause harmful effects in the newborn because it passes into the alimentary tract where it undergoes rapid inactivation

Renal Impairment

• Caution; no dose adjustment recommended

Hepatic Impairment

• Caution; no dose adjustment recommended

Elderly

• Caution; no information available

Porphyria Information

• Not porphyrinogenic (NP)

Drugs in Sport

• Permitted - No warnings

Central Nervous System Disorders

• Headache

Cardiovascular Disorders

• Tachycardia
• Bradycardia
• Arrhythmia
• Myocardial ischaemia
• QTc prolongation
• Hypotension
• Haemorrhage

Respiratory Disorders

• Acute pulmonary oedema

Gastrointestinal Disorders

• Nausea and vomiting

Genitourinary Disorders

• Uterine hypertonus
• Tetanic contractions of uterus
• Uterine rupture

Endocrine and Metabolic Disorders

• Water intoxication
• Maternal hyponatraemia
• Neonatal hyponatraemia

Immune, Blood and Lymphatic System Disorders

• Disseminated intravascular coagulation
• Anaphylaxis

Skin and Subcutaneous Tissue Disorders

• Rash
• Angioedema
• Flushing

Others

• Fetal distress syndrome
• Fetal Asphyxia 
• Fetal Death

• Prostaglandins
• Prostaglandin analogues
• QT prolonging agents
• Inhalation anaesthetics
• Vasoconstrictors
• Sympathomimetics
• Caudal anaesthetics

• Fetal heart rate  
• Vital signs
• Fluid intake and output

Administration directions for infusion (Induction/Augmentation of labour)

NOTE: Based on different fluid policies in different departments, there are different ways of diluting oxytocin for infusion. The table given below is simply one suggested example of how to infuse this drug for induction/augmentation of labour

Time after starting (min)	Oxytocin (milliunits/min)	Rate (ml/hr) Dilution: 2 IU/200ml normal saline
0	2	12
30	4	24
60	6	36
90	8	48
120	10	60
150	12	72
180	16	96
210	20	120

 

• Oxytocin must only be administered as an i.v. infusion and never by i.v. bolus injection as it may cause acute short-lasting hypotension accompanied by flushing and reflex tachycardia

Oxytocin is a synthetic peptide, which is released by the posterior pituitary and released into the systemic circulation in response to suckling and labour. Oxytocin stimulates the smooth muscle of the uterus, more powerfully towards the end of pregnancy, during labour, and immediately postpartum. Oxytocin elicits rhythmic contractions in the upper segment of the uterus, similar in frequency, force and duration to those observed during labour.

Injection (per ml) 5iu

• Spec-Oxytocin (Specpharm)
• Syntocinon (Mylan) originator

Injection (per ml) 10iu

• Spec-Oxytocin (Specpharm)
• Syntocinon (Mylan) originator

COMBINATION PREPARATIONS

Ergometrine/ Oxytocin

Injection (per ml) 0.5mg/5iu

• Syntometrine (Adcock)