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a hypothalamic hormone stored in and released from the posterior pituitary; it may also be prepared synthetically or obtained from the posterior pituitary of domestic animals. It acts as a powerful stimulant to the pregnant uterus, especially toward the end of gestation, and also causes milk to be expressed from the alveoli into the lactiferous ducts during breastfeeding. Injection of oxytocin may be used to induce labor or strengthen uterine contractions during labor, to contract uterine muscle after delivery of the placenta, and to control postpartum hemorrhage. It must be administered with care to avoid trauma to the mother or infant by hyperactivity of uterine muscles during labor. Oxytocin also may be administered intravenously by slow drip or applied to the mucous membranes of the nasal cavity to be absorbed into the bloodstream.
oxytocin challenge test (OCT) a type of contraction stress test to assess placental reserve for transmitting oxygen to the fetus and detecting insufficiency by observing the fetal heart rate response to oxytocin-induced contraction. See also fetal monitoring.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


Pitocin, Syntocinon (CA) (UK), Syntometrine (UK)

Pharmacologic class: Posterior pituitary hormone

Therapeutic class: Uterine-active agent

Pregnancy risk category NR

FDA Box Warning

• Drug isn't indicated for elective induction of labor (defined as initiation of labor in pregnant woman with no medical indications for induction). Available data aren't adequate to evaluate benefits versus risk.


Unknown. Thought to directly stimulate smooth muscle contractions in uterus and cervix.


Injection: 10 units/ml ampule or vial

Indications and dosages

To induce or stimulate labor

Adults: Initially, 1-ml ampule (10 units) in compatible I.V. solution infused at 1 to 2 milliunits/minute (0.001 to 0.002 units/minute). Increase rate in increments of 1 to 2 milliunits/minute q 15 to 30 minutes until acceptable contraction pattern is established.

To control postpartum bleeding

Adults: 10 to 40 units in compatible I.V. solution infused at rate adequate to control bleeding; or 10 units I.M. after placenta delivery

Incomplete abortion

Adults: 10 units in compatible I.V. solution infused at 10 to 20 milliunits/minute (0.01 to 0.02 units/minute)

Off-label uses

• Antepartal fetal heart rate testing

• Breast enlargement


• Hypersensitivity to drug

• Cephalopelvic disproportion

• Fetal distress when delivery is not imminent

• Prolonged use in uterine inertia or severe toxemia

• Hypertonic or hyperactive uterine pattern

• Unfavorable fetal position or presentation that's undeliverable without conversion

• Labor induction or augmentation when vaginal delivery is contraindi-cated (as in invasive cervical cancer, active genital herpes, or total placenta previa)


Use cautiously in:

• previous cervical or uterine surgery, history of uterine sepsis

• breastfeeding patients.


• Reconstitute by adding 1 ml (10 units) to 1,000 ml of normal saline solution, lactated Ringer's solution, or dextrose 5% in water.

Don't give by I.V. bolus injection.

• Infuse I.V. using controlled-infusion device.

• Be aware that drug isn't routinely given I.M.

• Know that drug should be given only to inpatients at critical care facilities when prescriber is immediately available.

Adverse reactions

CNS: seizures, coma, neonatal brain damage, subarachnoid hemorrhage

CV: premature ventricular contractions, arrhythmias, neonatal bradycardia

GI: nausea, vomiting

GU: postpartal hemorrhage; pelvic hematoma; uterine hypertonicity, spasm, or tetanic contraction; abruptio placentae; uterine rupture (with excessive doses)

Hematologic: afibrinogenemia

Hepatic: neonatal jaundice

Other: hypersensitivity reactions including anaphylaxis, low 5-minute Apgar score (neonate)


Drug-drug. Sympathomimetics: postpartal hypertension

Thiopental anesthetics: delayed anesthesia induction

Vasoconstrictors: severe hypertension (when given within 3 to 4 hours of oxytocin)

Drug-herbs. Ephedra (ma huang): increased hypertension

Patient monitoring

Continuously monitor contractions, fetal and maternal heart rate, and maternal blood pressure and ECG. Discontinue infusion if uterine hyper-activity occurs.

Monitor patient extremely closely during first and second stages of labor because of risk of cervical laceration, uterine rupture, and maternal and fetal death.

• When giving drug to control postpartal bleeding, monitor and record vaginal bleeding.

• Assess fluid intake and output. Watch for signs and symptoms of water intoxication.

Patient teaching

• Inform patient about risks and benefits of oxytocin-induced labor.

Teach patient to recognize and immediately report adverse drug effects.


McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved

ox·y·to·cin (OXT),

A nonapeptide neurohypophysial hormone, differing from human vasopressin in having a leucyl residue at position 8 and an isoleucyl residue at position 3, that causes myometrial contractions at term and promotes milk release during lactation; used to induce or stimulate labor, to manage postpartum hemorrhage and atony, and to relieve painful breast engorgement.
Synonym(s): ocytocin
[G. okytokos, swift birth]
Farlex Partner Medical Dictionary © Farlex 2012


1. A short polypeptide hormone, C43H66N12O12S2, released from the posterior lobe of the pituitary gland, that stimulates the contraction of smooth muscle of the uterus during labor and facilitates ejection of milk from the breast during nursing.
2. A synthetic form of this hormone, used as a drug to induce labor and to control postpartum hemorrhage.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Endocrinology A nonapeptide hormone which stimulates contraction of uterine smooth muscles and promotes milk ejection in females. Cf ADH.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A nonapeptide neurohypophysial hormone that causes myometrial contractions at term and promotes milk release during lactation; used for the induction or stimulation of labor, in the management of postpartum hemorrhage and atony, and to relieve painful breast engorgement. It is produced in the posterior pituitary gland.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


An OXYTOCIC hormone produced by the pituitary gland. The hormone promotes contraction of the womb and the letdown of milk during suckling. It is used as a drug in obstetrics to bring on labour at term and to augment slow labour. There is recent evidence that the hormone may have a role to play in promoting trust between humans. The drug is on the WHO official list. A brand name is Syntocinon.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


a hormone secreted by the posterior lobe of the PITUITARY GLAND,causing contraction of the uterine muscle. The hormone is important to parturition and, afterwards, for getting the uterus back to its normal size and shape.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005


A hormone that stimulates the uterus to contract during child birth and the breasts to release milk.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


(OXT) (ok'si-tō'sin)
Nonapeptide neurohypophysial hormone that causes myometrial contractions at term and promotes milk release during lactation.
Medical Dictionary for the Dental Professions © Farlex 2012
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