Oxytocin


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : IV Adjunct in abortion 10-20 milliunits/min. Max total dose: 30 u in a 12-hr period. Postpartum haemorrhage 10-40 u by infusion at a rate to control uterine atony. Labour induction 1-2 milliunits/min, may increase at intervals of at least 30 mins till a max of 3-4 contractions every 10 mins. Max: 32 milliunits/min and ≤5 u/day. Not to be given w/in 6 hr after administration of vag prostaglandins. Oxytocin challenge test for evaluating of foetal distress Dilute 5-10 u in 1 L of 5% dextrose inj. Initial: Drug infused in the mother via infusion at a rate of 0.5 milliunits/min. May gradually increase infusion rate. Max: 20 milliunits/min. Discontinue infusion when 3 moderate uterine contractions occur w/in one 10-minute interval. Compare baseline and oxytocin-induced foetal heart rates. Nasal Facilitate lactation Per spray contains 4 u: 1 spray into 1 nostril 5 mins before suckling.
Dosage Details
Intravenous
Postpartum haemorrhage
Adult: 10-40 units by infusion in 1000 mL of IV fluid at a rate sufficient to control uterine atony.

Intravenous
Adjunct in abortion
Adult: 10-20 milliunits/minute. Max total dose: 30 units in a 12-hr period.

Intravenous
Labour induction
Adult: 1-2 milliunits/minute, may increase at intervals of at least 30 minutes until a max of 3-4 contractions occur every 10 minutes. Not to exceed 32 milliunits/minute and no more than a total of 5 units should be given in 1 day. Not to be given within 6 hr after admin of vaginal prostaglandins. Monitor uterine contractions and foetal heart rate continuously. Withdraw gradually once labour is progressing.

Intravenous
Oxytocin challenge test for evaluating of fetal distress
Adult: Dilute 5-10 units in 1 L of 5% dextrose inj. Initially, administer the drug in the mother via IV infusion at a rate of 0.5 milliunits/minute. May gradually increase infusion rate at intervals of 15-30 minutes. Max: 20 milliunits/minute. Monitor foetal heart rate and uterine contractions immediately before and during infusion. Discontinue infusion when 3 moderate uterine contractions occur within one 10-minute interval. Compare baseline and oxytocin-induced foetal heart rates. If no change occurs, repeat the test in 1 wk. Termination of pregnancy may be required if a late deceleration in foetal heart rate occurs.

Nasal
Facilitate lactation
Adult: 1 spray (4 units) into 1 nostril 5 minutes before suckling.
Reconstitution
Intravenous:
Postpartum haemorrhage: Postpartum uterine bleeding: oxytocin 10-40 units to running IV infusion, max 40 units/1000 ml.
Adjunct in abortion: Oxytocin 10 units to 500 ml of a physiologic saline solution or glucose 5%.
Labour induction: Oxytocin 10 units to 500-1000 ml normal saline or lactated Ringer's to produce a solution of 10 milliunits/ml, rotate solution to mix. Normally infused at 3 ml/hr (delivering 0.001 unit/min). For higher doses: oxytocin 30 units can be added to 500 ml of diluent and infused at 1 ml/hr (delivering 0.001 unit/min).
Incompatibility
Intravenous:
Postpartum haemorrhage: When admixed: fibrinolysin (human), norepinephrine, prochlorperazine edisylate, warfarin; variable compatibility with phytonadione.
Adjunct in abortion: When admixed: fibrinolysin (human), norepinephrine, prochlorperazine edisylate, warfarin; variable compatibility with phytonadione.
Labour induction: When admixed: fibrinolysin (human), norepinephrine, prochlorperazine edisylate, warfarin; variable compatibility with phytonadione.
Nasal:
When admixed: fibrinolysin (human), norepinephrine, prochlorperazine edisylate, warfarin; variable compatibility with phytonadione.
Contraindications
Cephalopelvic disproportion; abnormal presentation of the foetus; hydraminios; multiparae; previous caesarian section or other uterine surgery; hyperactive or hypertonic uterus, uterine rupture; contraindicated vaginal delivery (invasive cervical cancer, active genital herpes, prolapse of the cord, cord presentation, total placenta previa or vasa previa); foetal distress where delivery is not imminent; severe pre-eclamptic toxaemia.
Special Precautions
CV disorders; >35 yr; lactation. Monitor foetal and maternal heart rate, maternal BP and uterine motility. Monitor fluid intake and output during treatment. Discontinute immediately if the uterus is hypertonic or hyperactive or if there is foetal distress. Use of nasal spray may produce maternal dependence on its effects. IM admin not regularly used due to unpredictable effects of oxytocin. Not to be used for prolonged periods in resistant uterine inertia, severe pre-eclampsia, or severe CV disorders. Risk of water intoxication when used at high doses for prolonged periods.
Adverse Reactions
Foetus or neonate: Jaundice; arrhythmias, bradycardia; brain, CNS damage; seizure; retinal haemorrhage; low Apgar score. Mother: transient hypotension, reflex tachycardia; nasal irritation, rhinorrhoea, lachrymation (following nasal admin); uterine bleeding, violent contractions, hypertonicity; spasm; nausea, vomiting.
Potentially Fatal: Maternal water intoxication (especially with slow infusion over 24 hr); prolonged uterine contractions causing foetal hypoxia and death; rupture of gravid uterus; afibrinogenaemia; subarachnoid haemorrhage
IM/IV/Parenteral: C
Overdosage
Tetanic uterine contractions, impaired uterine blood flow, amniotic fluid embolism, uterine rupture, syndrome of inappropriate antidiuretic hormone secretion and seizures. Treatment: Supportive and symptom specific.
Drug Interactions
Possible severe hypertension if given within 3-4 hr of vasoconstrictor in association with a caudal block anaesthesia. Cyclopropane anaesthesia may increase risk of hypotension and maternal sinus bradycardia with abnormal AV rhythms. Dinoprostone and misoprostol may increase uterotonic effect of oxytocin, thus oxytocin should not be used within 6 hr after admin of vaginal prostaglandins. Concurrent use may increase the vasopressor effect of sympathomimetics.
Potentially Fatal: Concomitant use with prostaglandins increases risk of uterine rupture and cervical lacerations.
Action
Description: Oxytocin induces rhythmic uterine contraction which increases throughout the pregnancy, reaching the max at term by proliferating oxytocin receptors. It increases the tone and amplitude of the uterine contractions at small doses.
Onset: Uterine contractions: IM: 3-5 minutes; IV: approx 1 minute.
Duration: IM: 2-3 hr; IV: 1 hr.
Pharmacokinetics:
Absorption: Steady state is reached normally 40 minutes after parenteral admin.
Distribution: Distribution throughout extracellular fluid, small amounts reach foetus.
Metabolism: Rapidly via the liver and plasma (by oxytocinase); some metabolism via mammary gland.
Excretion: Elimination half-life: 1-5 minutes; excreted via urine.
Storage
Store at 2-8 °C.
Disclaimer: This information is independently developed by MIMS based on Oxytocin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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