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Tocolytic

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Tocolytic, Tocolysis

  • See Also
  1. Preterm Labor Management
  • Indications
  1. Preterm Labor
  • Contraindications (See specific medications)
  1. Intrauterine Fetal Demise or lethal fetal anomaly
  2. Nonreassuring Fetal Status
    1. Fetal Bradycardia <100
    2. Fetal Tachycardia >180
  3. Severe Preeclampsia or Eclampsia
  4. Maternal bleeding with hemodynamic instability
    1. Maternal Systolic Blood Pressure <90 mmHg
  5. Maternal cardiopulmonary symptoms (e.g. Shortness of Breath, Chest Pain)
  6. Chorioamnionitis
  • Preparations
  • Preferred Tocolytics
  1. General Indications
    1. Stops labor for 24-48 hours
    2. Allows maternal transport and Corticosteroid doses
  2. Magnesium Sulfate
    1. Load: 6 grams bolus IV over 20 min (Very high dose!, some protocols use 4 g load)
    2. Maintenance: 2 grams/hour IV infusion (max: 3 g/h)
    3. Must follow protocols for patient safety
    4. Tocolytic and neuroprotective (with decreased risk of Cerebral Palsy in deliveries before 32 weeks)
      1. Doyle (2009) Obstet Gynecol 113(6): 1327-33 [PubMed]
    5. Does not prevent preterm birth
      1. Gyetvai (1999) Obstet Gynecol 94:869-77 [PubMed]
  3. Indomethacin (Indocin)
    1. Load: 50-100 mg orally or rectally
    2. Maintenance: 25-50 mg orally every 4-6 hours for up to 48 hours
    3. Avoid use >48 hours (risk of oligohydramnios, premature closure ductus arteriosus)
    4. Not recommended after 32 weeks due to ductus arteriosus constriction
  4. Nifedipine (Procardia)
    1. Load: 30 mg orally
    2. Maintenance: 10-20 mg every 4-6 hours (max: 180 mg/day)
    3. Higher risk of maternal adverse effects when combined with Magnesium Sulfate
  • Preparations
  • Other Tocolytics
  1. Terbutaline
    1. Load: 0.25 mg SQ every 20-30 min for up to 4 doses
    2. Maintenance: 0.25 mg every 3-4 hours until Uterus quiet for 24 hours
    3. Effective at temporarily stopping contractions
      1. Results in shortest hospital triage stays
      2. Guinn (1997) Am J Obstet Gynecol 177:814-87 [PubMed]
    4. Oral Terbutaline is not effective in Preterm Labor
      1. Lewis (1996) Am J Obstet Gynecol 175:834-7 [PubMed]
  2. Ritodrine
    1. Not available in the United States as of 2013
    2. Curiously, was the only FDA approved Preterm Labor Tocolytic
    3. Not shown to be more effective than Placebo
    4. (1992) N Engl J Med 327:308-12 [PubMed]
  • References
  1. (2016) Obstet Gynecol 128(4):e155-64 [PubMed]
  2. Berkman (2003) Am J Obstet Gynecol 188:1648-59 [PubMed]
  3. Haas (2009) Obstet Gynecol 113(3): 585-94 [PubMed]
  4. Sayres (2010) Am Fam Physician 81(4): 477-84 [PubMed]