Oxytocin

(ox-ih-TOE-sin)

  Action:
Endogenous hormone with uterine stimulant properties and vasopressive and antidiuretic effects.

  Indications:
Initiation or improvement of uterine contractions to achieve early vaginal delivery for maternal or fetal reasons (IV); management of inevitable or incomplete abortion (IV); stimulation of uterine contractions during third stage of labor (IV); stimulation reinforcement of labor, as in selected cases of uterine inertia (IV). Control of postpartum bleeding or hemorrhage (IV, IM); initiation of milk let-down (nasal). Unlabeled use(s): Antepartum fetal heart rate testing; relief of breast engorgement.

  Contraindications:
Significant cephalopelvic disproportion; inadequate, undeliverable fetal position; obstetric emergencies in which surgical intervention is preferred; cases of fetal distress in which delivery is not imminent; prolonged use in uterine inertia or severe toxemia; hypertonic or hyperactive uterine patterns; when adequate uterine activity fails to achieve satisfactory response; induction or augmentation of labor when vaginal delivery is not indicated (eg, prolapse); pregnancy (nasal product only).

  Route/Dosage:

Induction or Stimulation of Labor

Adults:
IV 1 to 2 mU/min; adjust by no more than 1 to 2 mU/min at 15 to 30 min intervals until contraction pattern similar to normal labor is obtained.

Control of Postpartum Uterine Bleeding
IV infusion 10 to 40 U in 1000 mL diluent to run as infusion at rate necessary to control uterine atony. IM 10 U (1 mL) after delivery of placenta.

Treatment of Incomplete or Inevitable Abortion
IV infusion 10 to 20 mU/min.

Initial Milk Let-Down
Nasal 1 spray into one or both nostrils 2 to 3 min before nursing or pumping of breasts.

  Interactions:

Cyclopropane anesthesia: May cause maternal hypotension, bradycardia and abnormal atrioventricular rhythms.

Parenteral sympathomimetics (eg, methoxamine, dopamine): Increased pressor effect, possibly resulting in postpartum hypertension.

INCOMPATIBILITIES: Sodium bicarbonate. Oxytocin is rapidly decomposed in the presence of sodium bisulfite.

  Lab Test Interferences:
None well documented.

  Adverse Reactions:

CV:

Cardiac arrhythmias; fetal reactions include bradycardia, premature ventricular contractions, death, jaundice, low Apgar scores, retinal hemorrhage and other arrhythmias.

CNS:

Neurologic damage; convulsions.

GI:

Nausea; vomiting.

GU:

Postpartum hemorrhage; cervical/vaginal lacerations; uterine hypertoxicity; uterine rupture; tetanic contractions; decreased uterine blood flow; pelvic hematoma.

RESP:

Hypoxia.

OTHER:

Maternal reactions include anaphylaxis; death; increased blood loss.

  Precautions:

Pregnancy: No indication for use in first trimester unless related to spontaneous or induced abortion.

Lactation: Excreted in breast milk. If used postpartum to control bleeding, patient should not nurse for 24 hr after last dose.

Children: Contraindicated in children.

Special risk patients: Not recommended in prematurity, borderline cephalopelvic disproportion, previous major surgery on cervix or uterus (including cesarean section), uterine over-distention, grand multiparity, history of uterine sepsis, traumatic delivery, fetal distress, partial placenta previa or invasive cervical carcinoma, except in unusual circumstances.

Mortality: Hypertensive episodes, subarachnoid hemorrhage and rupture of uterus have resulted in maternal deaths. Fetal deaths and infant brain damage have been reported with IV use during first and second stages of labor.

Overstimulation of uterus: Can occur and can be hazardous to mother and fetus.

Water intoxication: Consider possibility when patient is receiving oxytocin by IV infusion and fluids by mouth.

  Administration/Storage:

• Add 1 mL (10 U) to 500 to 1000 mL normal saline or 5% Dextrose in Water to prepare infusion solution. Final concentration will be 20 mU/mL and 10 mU/mL, respectively.
• Always use infusion pump to control IV oxytocin administration.
• When administering by IV infusion, rotate solution gently to distribute drug throughout solution.
• When administering drug by nasal spray, ensure that patient is seated (patient should not lie down); hold squeeze bottle upright (do not tilt hand); spray into one or both nostrils 2 to 3 min before nursing or pumping breasts.

  Assessment/Interventions:

• Obtain patient history, including drug history and any allergies. Note hypersensitivity to drug, epilepsy, nephritis, placenta previa, umbilical cord prolapse or other potential contraindications.
• Have emergency resuscitation equipment readily available.
• Assess cardiovascular function before administration and frequently during IV therapy.
• Assess fetal maturity, presentation, and pelvic adequacy before administration.
• Monitor vital signs, I&O and strength, duration, and frequency of contractions throughout infusion.
• If contractions occur < 2 min apart, last 60 to 90 sec or longer, or if significant change in fetal heart rate develops, stop infusion and turn patient on left side. Notify health care provider.
• If maternal heartbeat becomes irregular, BP rises, skin color changes or if patient develops chest discomfort, notify health care provider at once.
• Monitor patient for signs of water intoxication. If signs of water intoxication occur (eg, drowsiness, listlessness, confusion, headache, anuria), notify health care provider.
• Check fundus frequently during first few hours postpartum.
• Inspect nasal passages frequently when given nasally and look for irritation, ulcerations and rhinorrhea.

  Patient/Family Education:

• Teach patient how to administer nasal spray (clear nasal passages first; sit; do not lie down or tilt head back; hold bottle upright into vertical nares).
• Explain purpose of IV oxytocin to patient and family.
• Tell patient that early contractions will feel like strong menstrual cramps.

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