II. Indications
- Labor Induction or Labor Augmentation
- Prevention of Postpartum Hemorrhage
III. Physiology
- Oxytocin is a hypothalamic polypetide stored in the posterior Pituitary Gland
- Oxytocin release is triggered by reflex response to Hypothalamus from infant sucking nipple
- Oxytocin effects
- Stimulates uterine contractions
- Stimulates milk ejection in lactating women
IV. Adverse Effects
- Uterine hypertonicity
- Uterine tetanic contractions and Fetal Distress
- Uterine Rupture
-
Water Intoxication (SIADH)
- Associated with slow infusion >24 hours
V. Pharmacokinetics: Intravenous Oxytocin
- Onset: 1 minute
- Duration: 30 minutes
- Half-Life: <5 minutes
VI. Dosing: Labor Induction or Labor Augmentation
- See Labor Induction
- Preparation: Oxytocin in Normal Saline Infusion
- Oxytocin 10 units in 1000 ml Normal Saline
- Starting rate of 6-12 ml/hour delivers 1-2 mU/minute
- Increasing rate 6 ml/hour delivers another 1 mU/min
- Oxytocin 20 units in 1000 ml Normal Saline
- Starting rate of 3-6 ml/hour delivers 1-2 mU/minute
- Increasing rate 3 ml/hour delivers another 1 mU/min
- Oxytocin 10 units in 1000 ml Normal Saline
- Protocol: Low Dose (preferred)
- Start: 0.5 to 2 mIU/minute
- Increase: 1-2 mU/minute every 15-40 minutes
- Base Pitocin rate changes on contractions
- After 8 mIU/minute, may then increase by 2 mIU/minute
- Maximum: 40 mIU/minute
- Protocol: High Dose
- Low dose protocol is preferred in all patients (see Labor Induction for efficacy)
- Use only in Nulliparous patients only
- See Monitoring below
- Start: 6 mIU/minute
- Increase: 3-6 mIU/minute every 15-40 minutes
- Maximum: 40-42 mIU/minute
- As of 2019, evidence is against the use of high dose Oxytocin (see Labor Induction for efficacy)
VII. Dosing: Postpartum Hemorrhage Management and Prophylaxis
-
Postpartum Hemorrhage prevention after Vaginal Delivery
- Oxytocin 10 units IM after delivery
- Oxytocin 10-40 units in 1 L IV fluid (NS, LR, D5W)
-
Postpartum Hemorrhage prevention after cesarean
- High dose Oxytocin prevents atony
- Dose: Oxytocin 2667 mU/min for 30 minutes
- Munn (2001) Obstet Gynecol 98:386-90 [PubMed]