Obstetrics Book



Aka: Oxytocin, Pitocin
  1. See Also
    1. Uterotonic Medication
  2. Indications
    1. Labor Induction or Labor Augmentation
    2. Prevention of Postpartum Hemorrhage
  3. Physiology
    1. Oxytocin is a hypothalamic polypetide stored in the posterior Pituitary Gland
    2. Oxytocin release is triggered by reflex response to Hypothalamus from infant sucking nipple
    3. Oxytocin effects
      1. Stimulates uterine contractions
      2. Stimulates milk ejection in lactating women
  4. 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
  5. Pharmacokinetics: Intravenous Oxytocin
    1. Onset: 1 minute
    2. Duration: 30 minutes
    3. Half-life: <5 minutes
  6. Dosing: Labor Induction or Labor Augmentation
    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)
  7. Dosing: Postpartum Hemorrhage Management and Prophylaxis
    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]
  8. References
    1. LeFevre (2021) Am Fam Physician 103(2): 90-6 [PubMed]

Oxytocin (C0030095)

Definition (MSH) A nonapeptide hormone released from the neurohypophysis (PITUITARY GLAND, POSTERIOR). It differs from VASOPRESSIN by two amino acids at residues 3 and 8. Oxytocin acts on SMOOTH MUSCLE CELLS, such as causing UTERINE CONTRACTIONS and MILK EJECTION.
Definition (NCI) Oxytocin (125 aa, ~13kDa) is encoded by the human OXT gene. This protein plays a role in smooth muscle contraction in both the mammary gland and uterus. Oxytocin also is involved in maternal-newborn bonding, cognition and many other psychological and physiological processes.
Definition (CSP) peptide hormone produced by the posterior lobe of the pituitary gland that induces contraction of the smooth muscle of the uterus and the myoepithelial cells of the mammary gland.
Concepts Pharmacologic Substance (T121) , Hormone (T125) , Amino Acid, Peptide, or Protein (T116)
MSH D010121
SnomedCT 12369008, 112115002
LNC LP15767-4, MTHU013002
English Ocytocin, Oxytocin, Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2, cyclic 1-6 disulfide, oxytocin, oxytocics oxytocin, oxytocin (medication), OXYTOCIN, Oxytocin [Chemical/Ingredient], ocytocin, Oxytocin preparation, Oxytocin product, Oxytocin (substance), Oxytocin preparation (product), Oxytocin preparation (substance), OXT
Swedish Oxytocin
Spanish preparado de oxitocina, preparado con oxitocina (producto), preparado con ocitocina, oxitocina (producto), preparado con oxitocina, ocitocina, oxitocina (sustancia), oxitocina, preparado de oxitocina (sustancia), preparado de ocitocina, preparado de oxitocina (producto), Oxitocina
Czech oxytocin
Finnish Oksitosiini
French Oxytocine, Ocytocine
Japanese オシトシン, オキシトシン
Polish Oksytocyna, Ocytocyna
Norwegian Oxytocin, Oksytocin
Portuguese Oxitocina, Ocitocina
German Ocytocin, Oxytocin
Italian Ossitocina
Derived from the NIH UMLS (Unified Medical Language System)

Pitocin (C0733348)

Concepts Pharmacologic Substance (T121) , Hormone (T125) , Amino Acid, Peptide, or Protein (T116)
MSH D010121
French Pitocine
English pitocin, Pitocin
Norwegian Pitocin
Derived from the NIH UMLS (Unified Medical Language System)

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