Pharm
Oxytocin
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Oxytocin
, Pitocin
See Also
Uterotonic Medication
Indications
Labor Induction
or
Labor Augmentation
Prevention of
Postpartum Hemorrhage
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
Adverse Effects
Uterine hypertonicity
Uterine tetanic contractions and
Fetal Distress
Uterine Rupture
Water Intoxication
(
SIADH
)
Associated with slow infusion >24 hours
Pharmacokinetics
Intravenous Oxytocin
Onset: 1 minute
Duration: 30 minutes
Half-Life
: <5 minutes
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
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)
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]
References
LeFevre (2021) Am Fam Physician 103(2): 90-6 [PubMed]
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