Pharm

Oxytocin

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Oxytocin, Pitocin

  • Adverse Effects
  1. Uterine hypertonicity
    1. Uterine tetanic contractions and Fetal Distress
    2. Uterine Rupture
  2. Water Intoxication (SIADH)
    1. Associated with slow infusion >24 hours
  • Pharmacokinetics
  • Intravenous Oxytocin
  1. Onset: 1 minute
  2. Duration: 30 minutes
  3. Half-life: <5 minutes
  1. See Labor Induction
  2. Preparation: Oxytocin in Normal Saline Infusion
    1. Oxytocin 10 units in 1000 ml Normal Saline
      1. Starting rate of 6-12 ml/hour delivers 1-2 mU/minute
      2. Increasing rate 6 ml/hour delivers another 1 mU/min
    2. Oxytocin 20 units in 1000 ml Normal Saline
      1. Starting rate of 3-6 ml/hour delivers 1-2 mU/minute
      2. Increasing rate 3 ml/hour delivers another 1 mU/min
  3. Protocol: Low Dose (preferred)
    1. Start: 0.5 to 2 mIU/minute
    2. Increase: 1-2 mU/minute every 15-40 minutes
      1. Base Pitocin rate changes on contractions
      2. After 8 mIU/minute, may then increase by 2 mIU/minute
    3. Maximum: 40 mIU/minute
  4. Protocol: High Dose
    1. Low dose protocol is preferred in all patients (see Labor Induction for efficacy)
    2. Use only in Nulliparous patients only
    3. See Monitoring below
    4. Start: 6 mIU/minute
    5. Increase: 3-6 mIU/minute every 15-40 minutes
    6. Maximum: 40-42 mIU/minute
    7. As of 2019, evidence is against the use of high dose Oxytocin (see Labor Induction for efficacy)
  1. Postpartum Hemorrhage prevention after Vaginal Delivery
    1. Oxytocin 10 units IM after delivery
    2. Oxytocin 10-40 units in 1 L IV fluid (NS, LR, D5W)
  2. Postpartum Hemorrhage prevention after cesarean
    1. High dose Oxytocin prevents atony
    2. Dose: Oxytocin 2667 mU/min for 30 minutes
    3. Munn (2001) Obstet Gynecol 98:386-90 [PubMed]