Version May 2024
Elective induction of labor is defined as the initiation of labor in a pregnant individual who has no medical indications for induction. Since the available data are inadequate to evaluate the benefits-to-risks considerations, oxytocin is not indicated for elective induction of labor.
Note: The use of one standardized concentration and administration protocol (eg, the rate and interval for dose increases) for the induction or augmentation of labor and the management of postpartum uterine bleeding is recommended to prevent errors (Ref). Dosage is individualized for each patient using the lowest effective dose, determined by uterine response (ie, contractions and fetal heart rate).
Induction or stimulation of labor: Administration requires the use of an infusion pump. Note: The ideal dosing regimen has not been determined and various protocols are available (Ref); refer to institution-specific protocol. To prevent medication errors, the dose should be administered using a ready-to-use standardized infusion protocol (Ref). Consider discontinuing the oxytocin infusion once cervical dilation is 5 to 6 cm and adequate contractions are present (Ref). Discontinue the oxytocin infusion immediately in the event of uterine hyperactivity and/or fetal distress. If uterine contractions become too powerful, the infusion can be stopped abruptly.
Initial: IV: 0.5 to 1 milliunits/minute; gradually increase dose in increments of 1 to 2 milliunits/minute every 30 to 60 minutes until desired contraction pattern is established; dose may be decreased by similar increments after desired frequency of contractions is reached and labor has progressed to 5 to 6 cm cervical dilation. Higher infusion rates may be needed prior to term due to a lower sensitivity of the uterus. Infusion rates up to 6 milliunits/minute provide oxytocin levels similar to those with spontaneous labor; rates >9 to 10 milliunits/minute are rarely required in patients at term.
Low-dose regimens (off-label dose):
Initial: IV: 0.5 to 2 milliunits/minute; incrementally increase by 1 to 2 milliunits/minute every 15 to 40 minutes (Ref).
OR
Initial: IV: 2 milliunits/minute; incrementally increase by 2 milliunits/minute every 30 minutes to a maximum of 20 milliunits/minute (Ref).
High-dose regimens (off-label dose):
Initial: IV: 6 milliunits/minute; incrementally increase by 3 to 6 milliunits/minute every 15 to 40 minutes. Reduce the incremental increase to 3 milliunits/minute if uterine tachysystole occurs; reduce the incremental increase to 1 milliunit/minute for recurrent uterine tachysystole (Ref).
OR
Initial: IV: 4 milliunits/minute; incrementally increase by 4 milliunits/minute every 15 minutes to a maximum of 40 milliunits/minute (Ref).
Maximum dose: Not well established; refer to institution-specific protocol. Dosage is individualized for each patient using the lowest effective dose, determined by uterine response (ie, contractions and fetal heart rate). Although some protocols suggest maximum doses, higher doses (eg, 90 milliunits/minute) have been used (Ref).
Dose adjustment for oxytocin-induced uterine tachysystole:
Normal fetal heart rate (FHR): If management with maternal repositioning and administration of IV fluids (if needed) is not effective after 10 to 15 minutes, decrease oxytocin infusion by at least 50%. Discontinue oxytocin if uterine activity does not return to normal after an additional 10 to 15 minutes (Ref).
Indeterminate or abnormal FHR: Discontinue oxytocin (Ref).
Restarting oxytocin infusion: Oxytocin may be resumed following resolution of uterine tachysystole when contraction frequency, intensity, and duration, and FHR are normal. If infusion was discontinued for less than 20 to 30 minutes, initiate oxytocin at no more than 50% of the rate that caused the tachysystole and gradually adjust dose based on protocol and maternal/fetal status. If infusion was discontinued for more than 30 to 40 minutes, resume infusion at original dose ordered (Ref).
If uterine contractions become too powerful, the infusion can be stopped abruptly.
Duration of therapy:Consideration may be given to discontinue the oxytocin infusion once cervical dilation is 5 to 6 cm and adequate contractions are present (Ref).
Postpartum uterine bleeding: Note: Oxytocin is used for both prevention and treatment of postpartum hemorrhage associated with uterine atony following both vaginal and cesarean delivery (Ref).
Larger doses may be needed with unplanned cesarean deliveries if oxytocin was previously administered during labor; repeated doses may become ineffective due to desensitization of oxytocin receptors and changes in receptor density in the myometrium (Ref).
Oxytocin may be administered by slow IV bolus, IV infusion, or IM injection. Rapid IV bolus administration is associated with cardiovascular collapse (Ref); rapid IV boluses are not recommended for patients with cardiovascular risk factors (Ref).
To prevent postpartum hemorrhage, IV is preferred over IM injection following vaginal delivery in patients who already have IV access (Ref). Either route of administration may be used in patients undergoing cesarean delivery (Ref). Administer oxytocin during the third stage of labor after delivery of the placenta, delivery of the anterior shoulder, or after delayed umbilical cord clamping (Ref).
The optimal IV regimen has not been established (Ref); refer to institution-specific protocol. To prevent medication errors, the dose should be administered using a ready-to-use standardized infusion (Ref).
IM: 10 units after delivery of the placenta.
IV: 5 units (Ref) or 10 units (Ref) may be given initially and can be followed by a maintenance infusion of up to 10 units/hour (Ref). Maximum cumulative dose: 40 units (Ref). Adjust infusion rate to sustain uterine contraction and control uterine atony.
Lower bolus doses (0.5 to 3 units) for the prevention of postpartum bleeding have also been evaluated in patients undergoing elective cesarean delivery (Ref).
Adjunctive treatment of abortion:
Incomplete, inevitable, or elective abortion: IV: 10 units as an IV infusion after suction or a sharp curettage (used to help contract the uterus).
Midtrimester elective abortion: IV: 10 to 20 milliunits/minute; maximum total dose: 30 units/12 hours (may decrease injection to abortion time).
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified.
Frequency not defined:
Cardiovascular: Cardiac arrhythmia, hypertensive crisis, hypotension (Dyer 2011), subarachnoid hemorrhage, tachycardia (Dyer 2011), ventricular premature contractions
Endocrine & metabolic: Water intoxication (severe water intoxication with seizure and coma is associated with a slow oxytocin infusion over 24 hours)
Gastrointestinal: Nausea, vomiting
Genitourinary: Postpartum hemorrhage, uterine rupture
Hematologic & oncologic: Pelvic hematoma
Hypersensitivity: Anaphylaxis
Hypersensitivity to oxytocin or any component of the formulation; significant cephalopelvic disproportion; unfavorable fetal positions or presentations (such as transverse lies); fetal distress when delivery is not imminent; hypertonic or hyperactive uterus; contraindicated vaginal delivery (invasive cervical cancer, active genital herpes, prolapse of the cord, cord presentation, total placenta previa, or vasa previa); obstetrical emergencies where surgical intervention is favored; where adequate uterine activity fails to achieve satisfactory progress.
Canadian labeling: Additional contraindications (not in the US labeling): Severe toxemia; prematurity or unripe cervix; predisposition to uterine rupture (eg, grand multiparity, overdistention of the uterus, previous caesarian delivery, other surgery involving the uterus); prolonged use in uterine inertia; factors predisposing to thromboplastin or amniotic fluid embolism (eg, prolonged retention of dead fetus, placental abruption); serious medical or obstetric conditions and any condition in which fetal distress already occurs; inability of physician to be in attendance
Concerns related to adverse effects:
• Antidiuretic effect: Oxytocin may produce intrinsic antidiuretic effect (ie, water intoxication). Severe water intoxication with convulsions, coma, and death may occur, particularly with large doses (40 to 50 milliunits/minute) administered as a slow infusion over 24 hours and if the patient is receiving additional fluids.
• Cardiovascular effects: Arrhythmias, hypotension, myocardial ischemia, peripheral vasodilation, and tachycardia have been reported following administration. The risk of adverse events is influenced by dose and route of administration and is increased in patients with cardiovascular disease. Use with extreme caution in hemodynamically unstable patients (Dyer 2011).
• Maternal deaths: Maternal deaths caused by hypertensive episodes, subarachnoid hemorrhage, or rupture of the uterus and fetal deaths have occurred with oxytocic medications when used for induction of labor or for augmentation in the first and second stages of labor.
• Uterine effects: High doses or hypersensitivity to oxytocin may cause uterine hypertonicity, spasm, tetanic contraction, or rupture of the uterus. Prolonged infusion of oxytocin may saturate uterine receptors, causing inadequate uterine contractions and prolonged labor (AWHONN [Simpson 2020], Vallera 2017).
Other warnings/precautions:
• Appropriate use: Labor induction: Oxytocin is used to initiate or improve uterine contractions in order to replicate spontaneous labor and achieve a vaginal delivery. Use for induction of labor is generally not recommended in the following conditions: Fetal distress, hydramnios, partial placenta previa, prematurity, borderline cephalopelvic disproportion, or conditions where there is a predisposition for uterine rupture (eg, previous major surgery on cervix or uterus, cesarean section, overdistention of the uterus, grand multiparity, past history of uterine sepsis or traumatic delivery).
• Appropriate use: Abortion: For the adjunctive management of abortion in the first trimester, curettage is generally considered primary therapy. Oxytocin infusion in second trimester abortion will often be effective; however, other therapy may be required.
• Trained personnel: IV preparations should be administered by adequately trained individuals familiar with its use and able to identify complications; continuous observation is necessary for all patients. The use of one standardized concentration for the induction or augmentation of labor and the management of postpartum uterine bleeding is recommended to prevent errors (AWHONN 2021; AWHONN [Simpson 2020]; ISMP [Smetzer 2022]). Administration of ready-to-use bags boldly labeled on both sides (to differentiate from other solutions), not bringing the prepared oxytocin infusion to the patient's bedside until needed, and the use of standardized order sets are additional best practice safety interventions (ISMP [Smetzer 2022]).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Injection:
Pitocin: 10 units/mL (1 mL, 10 mL, 50 mL) [contains chlorobutanol (chlorobutol)]
Generic: 10 units/mL (1 mL, 10 mL, 30 mL)
Yes
Solution (Oxytocin Injection)
10 units/mL (per mL): $1.80 - $4.14
Solution (Pitocin Injection)
10 units/mL (per mL): $4.32
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Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution, Injection:
Generic: 10 units/mL (1 mL, 5 mL, 10 mL)
The use of one standardized concentration and administration protocol (eg, the rate and interval for dose increases) for the induction or augmentation of labor and the management of postpartum uterine bleeding is recommended to prevent errors (Ref). Administration of ready-to-use bags boldly labeled on both sides (to differentiate from other solutions), not bringing the prepared oxytocin infusion to the patient's bedside until needed, and the use of standardized order sets are additional best practice safety interventions (Ref).
Induction or augmentation of labor: IV administration requires the use of an infusion pump that allows minute-to-minute adjustments. The oxytocin solution can be piggybacked to an isotonic electrolyte infusion line proximal to the venipuncture site (Ref).
Incomplete or inevitable abortion: Administer by IV infusion.
Postpartum uterine bleeding: Administer by IV or IM. IM administration may be used when IV access is not available (Ref). IV push is not recommended; rapid IV bolus administration is associated with cardiovascular collapse (Ref). Slow IV injections (5 or 10 units over 1 minute) are preferred for patients without cardiovascular risk factors; very slow injections (>5 minutes) are preferred for patients with cardiovascular risk factors (Ref). Administration IV is preferred over IM injection for the prevention of postpartum hemorrhage following vaginal delivery in patients who already have IV access (Ref). Either route of administration may be used in patients undergoing cesarean delivery (Ref).
Hazardous agent (NIOSH 2016 [group 3]).
Use appropriate precautions for receiving, handling, storage, preparation, dispensing, transporting, administration, and disposal. Follow NIOSH and USP 800 recommendations and institution-specific policies/procedures for appropriate containment strategy (NIOSH 2016; USP-NF 2020).
Note: Facilities may perform risk assessment of some hazardous drugs to determine if appropriate for alternative handling and containment strategies (USP-NF 2020). Refer to institution-specific handling policies/procedures.
Antepartum: Initiation or improvement of uterine contractions, where this is desirable and considered suitable for reasons of fetal or maternal concern, in order to achieve vaginal delivery. Induction of labor in patients with a medical indication (eg, Rh problems [isoimmunization], maternal diabetes, preeclampsia, at or near term) when delivery is in the best interests of mother and fetus or when membranes are prematurely ruptured and delivery is indicated; stimulation or reinforcement of labor (as in selected cases of uterine inertia); adjunctive therapy in the management of incomplete or inevitable abortion.
Note: Oxytocin may also be used for other medical conditions in antepartum labor induction, including chronic or gestational hypertension, fetal compromise (eg, severe fetal growth restriction or oligohydramnios), or augmentation of labor, used when contractions are inadequate to produce a cervical change in dilation and effacement (ACOG 2009; AWHONN [Simpson 2020]).
Postpartum: To produce uterine contractions during the third stage of labor and to control postpartum bleeding or hemorrhage.
Elective induction of labor
The Institute for Safe Medication Practices (ISMP) includes this medication (oxytocin IV) among its list of medications that have a heightened risk of causing significant patient harm when used in error.
Oxytocin may be confused with OxyCONTIN
Pitocin may be confused with PIT or Pitressin (names to describe vasopressin), pitolisant
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
Amisulpride (Oral): May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk). Risk C: Monitor therapy
Azithromycin (Systemic): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Azithromycin (Systemic). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Carbetocin: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Carbetocin. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Carboprost Tromethamine: May enhance the adverse/toxic effect of Oxytocic Agents. Specifically, oxytocic effects may be enhanced. Risk X: Avoid combination
Chloroquine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Chloroquine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Clofazimine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Clofazimine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Dabrafenib: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Dabrafenib. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Dinoprostone: May enhance the adverse/toxic effect of Oxytocin. Specifically, oxytocic effects may be enhanced. Management: Concomitant use of dinoprostone and oxytocin is not recommended. If used sequentially, monitor uterine activity closely. Administer oxytocin 30 minutes after removing dinoprostone vaginal insert and 6 to 12 hours after the application of dinoprostone gel. Risk D: Consider therapy modification
Domperidone: QT-prolonging Agents (Moderate Risk) may enhance the QTc-prolonging effect of Domperidone. Management: Consider alternatives to this drug combination. If combined, monitor for QTc interval prolongation and ventricular arrhythmias. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider therapy modification
Encorafenib: May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
EPHEDrine (Nasal): Oxytocin may enhance the hypertensive effect of EPHEDrine (Nasal). Risk C: Monitor therapy
EPHEDrine (Systemic): Oxytocin may enhance the hypertensive effect of EPHEDrine (Systemic). Risk C: Monitor therapy
Fexinidazole: May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Fluorouracil Products: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Fluorouracil Products. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Gadobenate Dimeglumine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Gadobenate Dimeglumine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Gemeprost: May enhance the adverse/toxic effect of Oxytocin. Risk X: Avoid combination
Halofantrine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Halofantrine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Haloperidol: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Haloperidol. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Inotuzumab Ozogamicin: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Inotuzumab Ozogamicin. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Levoketoconazole: QT-prolonging Agents (Moderate Risk) may enhance the QTc-prolonging effect of Levoketoconazole. Risk X: Avoid combination
Lofexidine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Lofexidine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Midostaurin: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Midostaurin. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
MiSOPROStol: May enhance the adverse/toxic effect of Oxytocin. Specifically, oxytocic effects may be enhanced. Management: The manufacturer of misoprostol recommends avoiding concomitant use with oxytocin. Misoprostol may augment effects of oxytocin, particularly when given within 4 hours of oxytocin initiation. Risk D: Consider therapy modification
Ondansetron: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Ondansetron. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Pentamidine (Systemic): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Pentamidine (Systemic). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Pimozide: May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk). Risk X: Avoid combination
Piperaquine: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Piperaquine. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Probucol: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Probucol. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Agents (Highest Risk): Oxytocin may enhance the QTc-prolonging effect of QT-prolonging Agents (Highest Risk). Management: Consider alternatives to this drug combination. If combined, monitor for QTc interval prolongation and ventricular arrhythmias. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk D: Consider therapy modification
QT-prolonging Antidepressants (Moderate Risk): May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Antipsychotics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Antipsychotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Class IC Antiarrhythmics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Class IC Antiarrhythmics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-Prolonging Inhalational Anesthetics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of QT-Prolonging Inhalational Anesthetics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Kinase Inhibitors (Moderate Risk): May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Miscellaneous Agents (Moderate Risk): May enhance the QTc-prolonging effect of Oxytocin. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk): May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). QT-prolonging Moderate CYP3A4 Inhibitors (Moderate Risk) may increase the serum concentration of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Quinolone Antibiotics (Moderate Risk): QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of QT-prolonging Quinolone Antibiotics (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QT-prolonging Strong CYP3A4 Inhibitors (Moderate Risk): May enhance the QTc-prolonging effect of QT-prolonging Miscellaneous Agents (Moderate Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Sertindole: May enhance the QTc-prolonging effect of QT-prolonging Agents (Moderate Risk). Risk X: Avoid combination
Succinylcholine: Oxytocin may enhance the neuromuscular-blocking effect of Succinylcholine. Risk C: Monitor therapy
Toremifene: QT-prolonging Miscellaneous Agents (Moderate Risk) may enhance the QTc-prolonging effect of Toremifene. Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
Small amounts of exogenous oxytocin are expected to reach the fetal circulation. When used as indicated, teratogenic effects would not be expected. Nonteratogenic adverse reactions are reported in the neonate as well as the mother.
Oxytocin is used for augmentation of labor in patients making slow progress through the first stage of spontaneous labor. The time to delivery is shortened by ~2 hours (Alhafez 2020).
When used for induction of labor, maternal and fetal conditions, cervical status, gestational age, and other factors should be considered. Indications for induction of labor are not absolute but may include abruptio placentae, chorioamnionitis, post-term pregnancy, preeclampsia/eclampsia, premature rupture of membranes, fetal compromise (eg, severe fetal growth restriction, isoimmunization, oligohydramnios), fetal demise, or maternal medical conditions (eg, diabetes mellitus, kidney disease, chronic pulmonary disease, chronic or gestational hypertension, antiphospholipid syndrome) (ACOG 2009). Oxytocin should not be used to induce labor when spontaneous labor or vaginal birth would otherwise be contraindicated (ACOG 2009; AWHONN [Simpson 2020]).
Although the prescribing information contains a boxed warning against use for non-medical induction of labor, oxytocin may be used off-label for the elective induction of labor at 39 weeks gestation. Details for this use come from the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management). The study included low risk nulliparous patients with singleton gestations. Eligible patients did not have conditions requiring delivery prior to 40 weeks gestation and had reliable information of gestational age based on ultrasound and date of last menstrual period. A specific dosing protocol for oxytocin was not used in the study. The study showed no statistical difference in the primary composite outcome of perinatal mortality and severe perinatal morbidity while noting that cesarean delivery rate was significantly lower in the induction of labor group. In addition, there was a lower rate of gestational hypertension and preeclampsia as well as a reduced need for neonatal respiratory support in the first 72 hours of life. The American College of Obstetricians and Gynecologists (ACOG) and the Society of Maternal-Fetal (SMFM) state that it is reasonable to offer elective induction of labor to pregnant patients who meet the trial criteria. The recommendations are conditional, based on the preferences of the patient as well as the resources available (ACOG 2018; Grobman 2018; SMFM 2019).
Significant drug interactions exist (eg, dinoprostone, misoprostol), requiring dose/frequency adjustment or avoidance (ACOG 2009). Consult drug interactions database for more information.
Endogenous oxytocin mediates milk ejection. Administration of exogenous oxytocin may negatively impact breastfeeding. However, available studies have inconsistent results when evaluating the onset of lactogenesis, or the initiation and duration of breastfeeding. Outcomes may be influenced by study design, maternal dose, and indications for use (Buckley 2015; Erickson 2017; Fernández-Cañadas 2017; Fernández-Cañadas 2019; Gomes 2018).
Fluid intake and output during administration, uterine activity (tonus, amplitude, and frequency of contractions), maternal blood pressure; continuous electronic fetal heart rate monitoring in relation to uterine contractions.
Oxytocin stimulates uterine contractions by acting on receptors that trigger the release of intracellular calcium and local prostaglandin production. Oxytocin specific receptors are not present in the uterus until ~13 weeks' gestation and increase as pregnancy progresses and reach maximum concentration at term. Therefore, term pregnancies are more sensitive to lower oxytocin doses. The action of oxytocin is limited by the concentration of receptors in the smooth muscle of the uterus. Repeated doses may cause desensitization of the receptors and decreased response (Vallera 2017).
Onset of action: Uterine contractions: IM: 3 to 5 minutes; IV: ~1 minute
Duration: IM: 2 to 3 hours; IV: 1 hour
Half-life elimination: 1 to 6 minutes; decreased in late pregnancy and during lactation
Excretion: Urine (small amount unchanged)
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