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Nov.17.2022

Oxytocin

Indications/Dosage

Labeled

  • incomplete abortion
  • labor augmentation
  • labor induction
  • postpartum bleeding

Off-Label

  • fetal distress
† Off-label indication

For labor augmentation in patients with a medical necessity for labor induction, at or near to term, when delivery is in the best interests of the mother and the fetus

Continuous Intravenous Infusion dosage (low-dose)

Adults

0.5 to 1 milliunit/minute continuous IV infusion, initially. Titrate by 1 to 2 milliunits/minute every 30 to 60 minutes until the desired contraction pattern has been established. Once the desired frequency of contractions is obtained and labor has progressed to 5 to 6 cm dilation, reduce the dose similarly.[47239] Low-dose regimens and less frequent increases in dose are associated with decreased uterine hyperstimulation.[27317]

Continuous Intravenous Infusion dosage (high-dose†)

Adults

6 milliunits/minute continuous IV infusion, initially. Titrate by 3 to 6 milliunits/minute every 15 to 60 minutes until the required contraction pattern is established. Reduce the incremental increase if uterine hyperstimulation occurs. Max: 40 milliunits/minute.[27317] [65009]

Intravenous dosage (pulsatile regimen†)

Adults

Various protocols used off-label; pulsatile IV regimens are effective but may offer no clinical advantage. 1 milliunit oxytocin by intravenous injection every 8 to 10 minutes is one starting dose.[27317] One study used 2 milliunits IV injection every 6 minutes initially, with the dose doubled every 30 minutes until uterine contractions were established; the study compared this regimen to a traditional oxytocin infusion protocol. Cesarean section rates were not reduced and the pulse regimen was associated with increased rates of maternal and neonatal morbidity.[65008]

For the management of postpartum bleeding and to produce uterine contractions during the third stage of labor

Intravenous dosage

Adults

10 to 40 units in 500 to 1,000 mL of dextrose or electrolyte solution continuous IV infusion; adjust infusion rate to sustain uterine contraction and control uterine atony.[27827] [47239]

Intramuscular dosage

Adults

10 units IM as a single dose after delivery of the placenta.[27827] [47239]

For the adjunctive treatment of inevitable or incomplete abortion

Intravenous dosage

Adult females

10 to 20 milliunits/minute via continuous IV infusion. Do not exceed 30 units in a 12-hour period. Intravenous oxytocin is usually safe and effective for inducing labor for near term fetal demise, but is less effective remote from term.[27317]

For the evaluation of fetal distress† using an oxytocin-induced contraction stress test (aka, oxytocin challenge test or CST)†

Intravenous dosage

Adult females

Protocols may vary slightly by institution. Following baseline monitoring for 20 to 30 minutes, initiate at a low dose (e.g., 0.5 to 2.33 milliunits/minute) via continuous IV infusion to the mother. Double the infusion rate every 10 to 30 minutes until the frequency of the contractions are 3 within a 10-minute period (1 contraction every 3 to 4 minutes) and the duration is 40 to 60 seconds. When the desired number of contractions is obtained, record fetal heart rate and contractions until sufficient, then discontinue the infusion. Compare baseline and oxytocin-induced recordings.[62779] [62780]

Therapeutic Drug Monitoring

Maximum Dosage Limits

    Patients with Hepatic Impairment Dosing

    Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.

    Patients with Renal Impairment Dosing

    Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.

    † Off-label indication
    Revision Date: 11/17/2022, 07:31:32 AM

    References

    27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.27827 - American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins-Obstetrics. ACOG Practice Bulletin No. 183: Postpartum Hemorrhage. Obstet Gynecol 2017;130:e168-e186. Reaffirmed 2019.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.62779 - Gaziano EP, Hill DL, Freeman DW. The oxytocin challenge test in the management of high-risk pregnancies. Am J Obstet Gynecol. 1975;121:947-950.62780 - American College of Obstetricians and Gynecologists (ACOG). ACOG Practice bulletin Number 145: Antepartum Fetal Surveillance. Washington, DC: American College of Obstetricians and Gynecologists; 2014.65008 - Tribe RM, Crawshaw SE, Seed P, et al. Pulsatile versus continuous administration of oxytocin for induction and augmentation of labor: two randomized controlled trials. Am J Obstet Gynecol. 2012;206:230.e1-8. Epub 2011 Nov 7.65009 - Rossen J, Ostborg TB, Lindtjorn E, et al. Judicious use of oxytocin augmentation for the management of prolonged labor. Acta Obstet Gynecol Scand. 2016;95:355-361. Epub 2015 Dec 8.

    How Supplied

    Oxytocin Solution for injection

    Oxytocin 100unit/10ml Solution for Injection (42023-0141) (Par Pharmaceuticals, an Endo Company) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (10019-0291) (Baxter Anesthesia/Critical Care) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (63323-0012) (Fresenius Kabi AG) nullOxytocin 10unit/ml Solution for Injection package photo

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (10019-0291) (Hikma Pharmaceuticals USA inc.) null

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (00641-6114) (Hikma Pharmaceuticals USA Inc.) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (00641-6115) (Hikma Pharmaceuticals USA Inc.) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (42023-0140) (Par Pharmaceuticals, an Endo Company) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (43063-0029) (PD-Rx Pharmaceuticals, Inc.) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (00703-6275) (Teva Pharmaceuticals USA) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (00703-6271) (Teva Pharmaceuticals USA) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/ml Solution for Injection (00591-3553) (Teva/Actavis US) (off market)

    Oxytocin Solution for injection

    Oxytocin 10unit/mL Solution for Injection (NOVAPLUS) (63323-0012) (Fresenius Kabi AG) null

    Oxytocin Solution for injection

    Pitocin 10unit/ml Bulk Solution for Injection (42023-0130) (Par Pharmaceuticals, an Endo Company) (off market)

    Oxytocin Solution for injection

    Pitocin 10unit/mL Bulk Solution for Injection (42023-0130) (Par Pharmaceuticals, an Endo Company) null

    Oxytocin Solution for injection

    Pitocin 10unit/ml Solution for Injection (61570-0416) (Monarch Pharmaceuticals Inc a Pfizer Company) (off market)

    Oxytocin Solution for injection

    Pitocin 10unit/ml Solution for Injection (61570-0416) (Par Pharmaceuticals, an Endo Company) (off market)

    Oxytocin Solution for injection

    Pitocin 10unit/ml Solution for Injection (42023-0116) (Par Pharmaceuticals, an Endo Company) null

    Description/Classification

    Description

    Endogenous oxytocin is a natural human hormone secreted by the supraoptic and paraventricular nuclei of the hypothalamus and stored in the posterior lobe of the pituitary. The pharmacologic and clinical properties of pharmacologic oxytocin, a synthetic agent, are identical to those of naturally occurring oxytocin. Oxytocin injection stimulates contraction of uterine smooth muscle during gestation and causes milk ejection after milk has been produced in the breast. Clinically, oxytocin is primarily used intravenously to induce labor, aid in the delivery of the placenta (third stage of labor), and control postpartum bleeding.[27317] Intranasal preparations of oxytocin, which were previously used to stimulate postpartum milk ejection, are no longer available in the U.S.

    Classifications

    • Genito-urinary System and Sex Hormones
      • Other Gynecologicals
        • Labor Inducers
    Revision Date: 02/18/2020, 04:51:14 PM

    References

    27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.

    Administration Information

    General Administration Information

    For storage information, see the specific product information within the How Supplied section.

    Hazardous Drugs Classification

    • NIOSH 2016 List: Group 3 [63664]
    • NIOSH (Draft) 2020 List: Table 2
    • Observe and exercise appropriate precautions for handling, preparation, administration, and disposal of hazardous drugs.
    • Use double chemotherapy gloves and a protective gown. Prepare in a biological safety cabinet or compounding aseptic containment isolator with a closed system drug transfer device. Eye/face and respiratory protection may be needed during preparation and administration.[63664][67506][67507]

    Route-Specific Administration

    Injectable Administration

    • Administer oxytocin by intravenous infusion or intramuscular injection; controlled intravenous (IV) infusion is usually preferred.
    • Prior to administration, an IV infusion of 0.9% Sodium Chloride or other appropriate IV fluid should be already running for use in case of adverse reactions.
    • Magnesium sulfate should be readily available for myometrial relaxation, if necessary.
    • The dosage of oxytocin is determined by the uterine response. Dosage and infusion must be individualized and initiated at a very low level. The manufacturer-supplied information is based upon various regimens and indications for obstetric use.
    • Visually inspect the parenteral product for particulate matter and discoloration prior to administration whenever solution and container permit.[47239][27317]

    Intravenous Administration

    Intravenous infusion:

    • The following recommendations for infusion solutions are from the package insert.[47239] However, experts recommend that institutions adopt standard oxytocin infusion concentrations for use, to help limit the potential for infusion and dosage errors.[65004]
      • Induction of labor: Dilute 1 mL (10 units) in 1,000 mL of a compatible IV infusion solution. Rotate infusion bottle for thorough mixing. The resultant infusion should contain 10 milliunits/mL.
      • Control of postpartum uterine bleeding: Dilute 10 to 40 units in a compatible IV solution or to an already infusing compatible IV solution. The maximum concentration is 40 units in 1,000 mL of solution.
      • Incomplete, inevitable, or elective abortion: Dilute 10 units in 500 mL of a compatible IV solution.
    • Administer using an infusion pump to ensure accurate dosing. Experts recommend the use of smart infusion pumps with an engaged dose error-reduction system for oxytocin infusions.[47239][65004]
    • When an oxytocin infusion is discontinued, promptly remove and discard any unused portion of the infusion and change the IV line to ensure no residual drug is left in the tubing.[65004]

    Intramuscular Administration

    Intramuscular injection:[47239]

    • Inject into a large muscle mass.

    Clinical Pharmaceutics Information

    From Trissel's 2‚Ñ¢ Clinical Pharmaceutics Database

    Oxytocin

    pH Range
    pH 3 to 5
    ReferencesAnon. Manufacturer's information and labeling. (Package insert).
    ReferencesAnon. The United States Pharmacopeia. Rockville, Maryland: The United States Pharmacopeial Convention. Current edition.
    Osmolality/Osmolarity
    Oxytocin 10 units/mL was very hypotonic having a measured osmolality of 24 mOsm/kg.
    ReferencesTrissel LA. Drug information- osmolalities. Data on file.
    Stability
    Oxytocin injection in intact containers stored as directed by the manufacturer is stable until the labeled expiration date. Oxytocin injection should not be used if it is discolored or has a precipitate. Infusion Solutions: The manufacturer recommends that oxytocin be diluted for intravenous infusion in dextrose 5% or sodium chloride 0.9%. Lactated Ringer's injection has also been suggested, but precipitation has been reported upon long-term storage (see below). Kirkland et al. reported that oxytocin is physically compatible in most common infusion solutions. Gard et al. reported that oxytocin 0.02 unit/mL in bags (plastic composition not reported) of lactated Ringer's and dextrose 5% in lactated Ringer's injections was stable by HPLC analysis for 216 hours (9 days) refrigerated at 5 degree C. Trissel et al. reported that oxytocin 0.08 unit/mL in dextrose 5% and in sodium chloride 0.9% was physically compatible and chemically stable for at least 90 days at room temperature near 23 degree C. In lactated Ringer's injection, oxytocin was physically compatible and chemically stable for up to 28 days at room temperature. However, a trace amount of white fluffy precipitation appeared after that time becoming visible precipitation after 42 days of storage. Paramedic Conditions: Gammon et al. reported on the stability of a number of drugs used by paramedics when exposed to the temperature range that is found in ambulances as documented by Brown et al. and Allegra et al. Undiluted oxytocin 10 units/mL injection was stored at temperatures that cycled every 24 hours from -6 to 54 degree C (2.12 to 129.2 degree F) for 28 days. The drug was exposed to a total of 336 hours at each of the temperature extremes. The mean kinetic temperature was 33 degree C. HPLC and ultraviolet spectrophotometry found drugs losses from 7 to 11% occurred over the 28-day test period.
    ReferencesAnon. Manufacturer's information and labeling. (Package insert).
    ReferencesAllegra JR, Brennan J, Lanier V, et al. Storage temperatures of out-of-hospital medications. Acad Emerg Med. 1999; 6
    ReferencesBrown LH, Bailey LC, Medwick T, et al. Medication storage on US ambulances: a prospective multi-center observational study. Pharm Forum. 2003; 29
    ReferencesGammon DL, Su S, Huckfeldt R, et al. Alteration in prehospital drug concentration after thermal exposure. Am J Emerg Med. 2008; 26
    ReferencesGard JW, Alexander JM, Bawdon RE, et al. Oxytocin preparation stability in several common obstetric intravenous solutions. Am J Obstet Gynecol. 2002; 186
    ReferencesKirkland WD, Jones RW, Ellis JR, et al. Compatibility studies of parenteral admixtures. Am J Hosp Pharm. 1961; 18
    ReferencesMcEvoy GK (ed). AHFS Drug Information (current edition). Bethesda, MD: American Society of Health-System Pharmacists.
    ReferencesTrissel LA. Zhang Y, Douglass K, et al. Extended stability of oxytocin in common infusion solutions. Int J Pharmaceut Compound. 2006; 10
    Light Exposure
    Mozziconacci and Schoeneich reported that oxytocin is sensitive to very intense ultraviolet (UV) light. The light exposure in this study was greater than natural sunlight.
    ReferencesMozziconacci O, Schoneich C. Photodegradation of oxytocin and thermal stability of photoproducts. J Pharm Sci. 2012; 101
    Freezing
    Oxytocin injection should be protected from freezing during storage.
    ReferencesAnon. Manufacturer's information and labeling. (Package insert).
    Filtration
    Butler et al. reported that Parke-Davis oxytocin 0.25 unit/mL in sodium chloride 0.9% delivered at 3 mL/minute apparently underwent binding initially to an Ivex-2 cellulose ester 0.22-micron filter, but no determination could be made regarding the extent of binding in normal administration situations. Additionally, whether any binding occurred at all when mixed in dextrose 5% was uncertain.
    ReferencesButler LD, Munson JM, DeLuca PP. Effect of inline filtration on the potency of low-dose drugs. Am J Hosp Pharm. 1980; 37
    Sorption Leaching
    Oxytocin has not been found to undergo substantial sorption to polyvinyl chloride (PVC) containers even during extended storage for 90 days.
    ReferencesTrissel LA. Zhang Y, Douglass K, et al. Extended stability of oxytocin in common infusion solutions. Int J Pharmaceut Compound. 2006; 10
    Other Information
    Oxytocin is cited by NIOSH as a drug that should be handled as hazardous. Oxytocin 1 unit is equal to about 2 to 2.2 micrograms. Bisulfite: Chang et al. reported that oxytocin appeared to undergo rapid decomposition when mixed with sodium bisulfite. Drugs such as norepinephrine bitartrate and some forms of epinephrine hydrochloride that contain a sulfite as an antioxidant in the formulation should not be mixed with oxytocin. Metal ions and buffers: Avanti et al. evaluated the effect on the stability of oxytocin 0.1 mg/mL in aqueous solutions by monovalent and divalent metal ions in acetate- and also citrate-buffer using reversed-phase HPLC, size exclusion HPLC analysis, and isothermal titration calorimetry. The monovalent ions Na+ and K+ (from chloride salts) in either acetate (10 mM) or citrate (5 and 10 mM) buffers did not alter oxytocin stability. Similarly, the divalent metal ion Ca++, Mg++, and Zn++ (from chloride solutions) in acetate buffer did not alter oxytocin stability. However, the three divalent metal ions in concentrations ranging from 2 to 50 mM in 5 or 10 mM citrate buffer substantially improved oxytocin stability, even at elevated temperature of 55 degree C. Long-term stability over 6 months at 40 degree C found remaining oxytocin concentrations increased by 80% with Ca++ and 90% with Mg++ in 10 mM citrate buffer solution.. Other Drugs: Oxytocin has been reported to be compatible with phytonadione in most common infusion solutions.
    ReferencesAnon. Preventing occupational exposure to antineoplastic and other hazardous drugs in health care settings. NIOSH Publication No. 2004-165. 2004; 165
    ReferencesAvanti C, Amorij JP, Setyaningsih D, et al. A new strategy to stabilize oxytocin in aqueous solutions: The effects of divalent metal ions and citrate buffer. AAPS J. 2011; 13
    ReferencesChang CH, Ashford WR, Ives DAJ, et al. Stability of oxytocin in various infusion solutions. Can J Hosp Pharm. 1972; 25
    ReferencesKirkland WD, Jones RW, Ellis JR, et al. Compatibility studies of parenteral admixtures. Am J Hosp Pharm. 1961; 18
    ReferencesMcEvoy GK (ed). AHFS Drug Information (current edition). Bethesda, MD: American Society of Health-System Pharmacists.
    Stability Max
    Maximum reported stability periods (See Stability): In D5W- 90 days at room temperature. In LR - 28 days at room temperature. In NS- 90 days at room temperature.
    ReferencesTrissel LA. Zhang Y, Douglass K, et al. Extended stability of oxytocin in common infusion solutions. Int J Pharmaceut Compound. 2006; 10
      Revision Date: 04/21/2022, 01:54:24 PMCopyright 2004-2023 by Lawrence A. Trissel. All Rights Reserved.

      References

      27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.63664 - CDC National Institute for Occupational Safety and Health (NIOSH). NIOSH List of Antineoplastic and Other Hazardous Drugs in Healthcare Settings 2016. DHHS (NIOSH) Publication Number 2016-161, September 2016. Available on the World Wide Web at https://www.cdc.gov/niosh/docs/2016-161/pdfs/2016-161.pdf?id=10.26616/NIOSHPUB201616165004 - Institute for Safe Medication Practices (ISMP). Errors associated with oxytocin use: A multiorganization analysis by ISMP and ISMP Canada. ISMP Medication Safety Alert - Acute Care Edition. 2020;25(3):1-5.67506 - American Society of Health-System Pharmacists. ASHP guidelines on handling hazardous drugs. Am J Health-Syst Pharm. 2018; 75:1996-2031.67507 - NIOSH [2016]. NIOSH Alert: Preventing Occupational Exposures to Antineoplastics and Other Hazardous Drugs in Health Care Settings. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2016-161.

      Adverse Reactions

      Severe

      • afibrinogenemia
      • anaphylactoid reactions
      • arrhythmia exacerbation
      • cervical laceration
      • coma
      • fetal death
      • intracranial bleeding
      • ocular hemorrhage
      • postpartum hemorrhage
      • pulmonary edema
      • retinal hemorrhage
      • seizures
      • uterine rupture
      • water intoxication

      Moderate

      • bleeding
      • blurred vision
      • fetal bradycardia
      • hematoma
      • hyperbilirubinemia
      • hypertension
      • jaundice
      • premature ventricular contractions (PVCs)
      • uterine contractions

      Mild

      • nausea
      • vomiting

      Some patients can experience a hypersensitive uterine reaction to the effects of oxytocin. Excessive doses can have the same effect. This can produce increased, hypertonic uterine contractions, possibly prolonged, resulting in a number of adverse reactions such as cervical laceration, postpartum hemorrhage, pelvic hematoma, and uterine rupture. Maternal deaths due to subarachnoid hemorrhage and uterine rupture have been associated with the use of parenteral oxytocic drugs for induction of labor or for augmentation in the first and second stages of labor.[47239]

      Cases of fatal afibrinogenemia and intracranial bleeding have been reported in women receiving oxytocin during labor. Maternal deaths due to subarachnoid hemorrhage and uterine rupture have been associated with the use of parenteral oxytocic drugs for induction of labor or for augmentation in the first and second stages of labor.[47239] In one case, subarachnoid hemorrhage mimicked acute water intoxication and delayed the diagnosis of hemorrhage after an oxytocin assisted labor.[27318] Neonatal retinal hemorrhage has also been reported.[47239]

      Adverse maternal cardiovascular effects from oxytocin may include arrhythmia exacerbation, premature ventricular contractions (PVCs), and hypertension. In the fetus or neonate, fetal bradycardia, PVCs, and other arrhythmias have been noted. In addition, cases of low Apgar scores at 5 minutes after birth have also been reported. Maternal deaths due to hypertensive episodes and fetal death due to various causes have been reported associated with the use of parenteral oxytocic drugs for induction of labor or for augmentation in the first and second stages of labor.[47239]

      Oxytocin has an antidiuretic effect, and severe and fatal water intoxication has been noted and may occur if large doses (40 to 50 milliunits/minute) are infused for long periods. For example, water intoxication with seizures and coma has occurred in association with a slow oxytocin infusion over a 24-hour period. Management of water intoxication includes immediate oxytocin cessation and supportive therapy. In the fetus or neonate, fetal death, permanent CNS or brain damage, and neonatal seizures have been noted with oxytocin. The rare complications of blurred vision, ocular hemorrhage (of the conjunctiva), and pulmonary edema have been associated with oxytocin induced water intoxication.[47239]

      Oxytocin administration has been associated with anaphylactoid reactions.[47239]

      Oxytocin-induced labor has been implicated in an increased incidence of neonatal hyperbilirubinemia, about 1.6 times more likely than after spontaneous labor. This can lead to neonatal jaundice.[47239]

      Nausea and vomiting have been noted with oxytoxin.[47239]

      Revision Date: 10/13/2022, 09:16:23 AM

      References

      27318 - Curless RV, Beaumont DM, Sinar EJ, et al. Subarachnoid hemorrhage mimicking acute water intoxication during labour augmented by oxytocin infusion. Br J Clin Pract 1990;44(12):637-638.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.

      Contraindications/Precautions

      Absolute contraindications are italicized.

      • cervical cancer
      • herpes infection
      • vasa previa
      • abnormal fetal position
      • breast-feeding
      • cephalopelvic disproportion
      • eclampsia
      • elective induction of labor
      • fetal distress
      • fetal prematurity
      • multiparity
      • placenta previa
      • pregnancy
      • requires a specialized care setting
      • requires an experienced clinician
      • surgery
      • uterine atony

      Oxytocin is contraindicated in patients with a known hypersensitivity to the drug or any of the specific product ingredients.[47239]

      Oxytocin is indicated during pregnancy to induce labor; it precipitates uterine contractions. There are no known indications for use of oxytocin in the first and second trimester of pregnancy other than in relation to spontaneous or induced abortion. Based on the wide experience with this drug and its chemical structure and pharmacological properties, it would not be expected to present a risk of fetal abnormalities when used as indicated.[47239] [27317]

      Endogenous oxytocin is involved in the process of lactation and therefore, oxytocin has been used in mothers having difficulty with engorgement and breast-feeding. Because several small studies have failed to show a beneficial effect, oxytocin is not used for this indication. Oxytocin is excreted in the breast-milk, but is not expected to have adverse effects in the infant.[47251]

      Use of oxytocin requires an experienced clinician who is trained in the administration and complications of the drug. Oxytocin use also requires a specialized care setting where intensive care and surgical facilities are immediately available. Furthermore, according to the manufacturer, oxytocin should only be used when induction of labor is necessary for medical reasons. It should not be used for elective induction of labor as available data are insufficient to evaluate the risk-benefit ratio in this indication. When oxytocin is used for induction or reinforcement of already existent labor, patients should be carefully selected. Pelvic adequacy must be considered and maternal and fetal conditions evaluated prior to initiation. The use of oxytocin is contraindicated in the following circumstances: where there is significant cephalopelvic disproportion, in unfavorable fetal positions or presentations which are undeliverable without conversion prior to delivery (i.e., transverse lies), in obstetrical emergencies where the benefit-to-risk ratio for either the fetus or the mother favors surgical intervention, in fetal distress where delivery is not imminent, where adequate uterine activity fails to achieve satisfactory progress, where the uterus is already hyperactive or hypertonic, and in cases where vaginal delivery is contraindicated (i.e., invasive cervical cancer, active herpes infection, total placenta previa, vasa previa, and cord presentation or prolapse of the cord). Except in unusual circumstances, oxytocin should be avoided when the following conditions or situations are present: evidence of fetal distress, hydramnios, fetal prematurity, abnormal fetal position (including unengaged head), partial placenta previa, borderline cephalopelvic disproportion, overdistention of the uterus, grand multiparity, any condition in which there is a predisposition for uterine rupture, such as a previous major surgery of the uterus or cervix (including cesarean section), overdistension of the uterus, past history of uterine sepsis or of traumatic delivery, or in any condition presenting as an obstetric emergency requiring surgical intervention. Due to the variability of the combinations of factors which may exist in these conditions, the definition of unusual circumstance must be left to the judgement of the physician. The decision can only be made by carefully weighing the potential benefits which oxytocin can provide in a given case against rare but definite potential for the drug to produce hypertonicity or tetanic spasm. During oxytocin administration, uterine contractions, fetal and maternal heart rate, maternal blood pressure, and, if possible, intrauterine pressure should be continuously monitored to avoid complications. Only intrauterine pressure recording can accurately measure the intrauterine pressure during contractions. A fetal scalp electrode provides a more dependable recording of the fetal heart rate than any external monitoring system. If uterine hyperactivity occurs, oxytocin administration should be immediately discontinued; oxytocin-induced stimulation of the uterine contractions usually decreases soon after discontinuance of the drug.[47239]

      Oxytocin may possess antidiuretic effects, and prolonged use can increase the possibility of an antidiuretic effect. Prolonged use of oxytocin and administration in large volumes of low-sodium infusion fluids are not recommended, particularly in patients with eclampsia or who have unresponsive uterine atony. In addition, consideration should be given to the possibility of water intoxication if the patient is receiving fluids by mouth. Antidiuretic effects have the potential to lead to water intoxication and convulsive episodes due to hypertension.[47239]

      Revision Date: 10/14/2022, 10:01:30 AM

      References

      27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.47251 - Mangesi L, Dowswell T. Treatments for breast engorgement during lactation. Cochrane Database Syst Rev. 2010;9:CD006946.

      Mechanism of Action

      Synthetic oxytocin elicits the same pharmacological response produced by endogenous oxytocin, with cervical dilation, parity, and gestational age as predictors of the dose response to oxytocin administration for labor stimulation.[27317] Oxytocin increases the sodium permeability of uterine myofibrils, indirectly stimulating contraction of the uterine smooth muscle. The uterus responds to oxytocin more readily in the presence of high estrogen concentrations and with the increased duration of pregnancy. There is a gradual increase in uterine response to oxytocin for 20 to 30 weeks gestation, followed by a plateau from 34 weeks of gestation until term, when sensitivity increases.[27317] Women who are in labor have a greater response to oxytocin compared to women who are not in labor; only very large doses will elicit contractions in early pregnancy. In the term uterus, contractions produced by exogenous oxytocin are similar to those that would occur during spontaneous labor. Oxytocin increases the amplitude and frequency of uterine contractions, which transiently impede uterine blood flow and decrease cervical activity, causing dilation and effacement of the cervix.

       

      Oxytocin causes contraction of the myoepithelial cells surrounding the alveolar ducts of the of the breast. This forces milk from the alveolar channels into the larger sinuses, and thus facilitates milk ejection. While oxytocin possesses no galactopoietic properties, if it is absent the milk-ejection reflex in the breast fails.

       

      Oxytocin causes dilation of vascular smooth muscle, thus increasing renal, coronary, and cerebral blood flow. Blood pressure usually remains unaffected, but with the administration of very large doses or high concentration solutions blood pressure may decrease transiently. This transient decrease in blood pressure leads to reflex tachycardia and an increase in cardiac output; any fall in blood pressure is usually followed by a small, but sustained, increase in blood pressure.

       

      Oxytocin does possess antidiuretic effects, but they are minimal. If oxytocin is administered with an excessive volume of electrolyte-free IV solution and/or at too rapid a rate, the antidiuretic effects are more apparent and water intoxication can result.

       

      Oxytocin appears to have important roles in sexual function and bonding responses in both males and females.[27315]

      Revision Date: 01/10/2018, 12:03:33 PM

      References

      27315 - Cabanac M, Pfaff DW, Ogawa S, et al. Neural oxytocinergic systems as genomic targets for hormones and as modulators of hormone-dependent behaviors. Results Probl Cell Differ 1999;26:91-105.27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.

      Pharmacokinetics

      Oxytocin administered effectively by parenteral injection. Steady-state is usually achieved in plasma by 40 minutes after parenteral administration.[27317] Oxytocin's plasma half-life is between 1 and 6 minutes. The drug distributes throughout the extracellular fluid, with minimal amounts reaching the fetus. Oxytocinase, a glycoprotein aminopeptidase that is capable of degrading oxytocin, is produced during pregnancy and is present in the plasma. Enzyme activity increases gradually until term approaches when there is a sharp rise in plasma levels and activity is high in the plasma, placenta, and uterus. After obstetric delivery, the enzyme activity declines. Oxytocinase most likely originates from the placenta and regulates the amount of oxytocin in the uterus; there is little or no degradation of oxytocin in men, nonpregnant women, or cord blood. Oxytocin is rapidly removed from the plasma by the liver and the kidneys, with only small amounts being excreted unchanged in the urine. Oxytocin is metabolized in the lactating mammary gland and is distributed into breast-milk.

       

      Affected cytochrome P450 (CYP450) isoenzymes and drug transporters: None

      Route-Specific Pharmacokinetics

      Oral Route

      Chymotrypsin, present in the GI tract, destroys oxytocin, rendering oral administration ineffective.

      Intravenous Route

      When administered by IV infusion, the uterus responds almost immediately to oxytocin, with response subsiding in about an hour.

      Intramuscular Route

      When oxytocin is administered by IM injection, the uterus responds within 3 to 5 minutes, with response subsiding in approximately 2 to 3 hours.

      Revision Date: 02/18/2020, 04:44:27 PM

      References

      27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.

      Pregnancy/Breast-feeding

      pregnancy

      Oxytocin is indicated during pregnancy to induce labor; it precipitates uterine contractions. There are no known indications for use of oxytocin in the first and second trimester of pregnancy other than in relation to spontaneous or induced abortion. Based on the wide experience with this drug and its chemical structure and pharmacological properties, it would not be expected to present a risk of fetal abnormalities when used as indicated.[47239] [27317]

      breast-feeding

      Endogenous oxytocin is involved in the process of lactation and therefore, oxytocin has been used in mothers having difficulty with engorgement and breast-feeding. Because several small studies have failed to show a beneficial effect, oxytocin is not used for this indication. Oxytocin is excreted in the breast-milk, but is not expected to have adverse effects in the infant.[47251]

      Revision Date: 10/13/2022, 01:13:42 PM

      References

      27317 - American College of Obstetrics and Gynecology (ACOG). ACOG Practice Bulletin Number 107: Clinical Management Guidelines for Obstetrician-Gynecologists. Induction of Labor. Washington, DC: American College of Obstetricians and Gynecologists; August 2009.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.47251 - Mangesi L, Dowswell T. Treatments for breast engorgement during lactation. Cochrane Database Syst Rev. 2010;9:CD006946.

      Interactions

      Level 1 (Severe)

      • Dinoprostone, Prostaglandin E2

      Level 2 (Major)

      • Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine
      • Acetaminophen; Chlorpheniramine; Phenylephrine
      • Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine
      • Acetaminophen; Dextromethorphan; Phenylephrine
      • Acetaminophen; Guaifenesin; Phenylephrine
      • Brompheniramine; Carbetapentane; Phenylephrine
      • Brompheniramine; Dextromethorphan; Phenylephrine
      • Brompheniramine; Phenylephrine
      • Carbetapentane; Chlorpheniramine; Phenylephrine
      • Carbetapentane; Diphenhydramine; Phenylephrine
      • Carbetapentane; Guaifenesin; Phenylephrine
      • Carbetapentane; Phenylephrine
      • Carbetapentane; Phenylephrine; Pyrilamine
      • Carbinoxamine; Phenylephrine
      • Carboprost Tromethamine
      • Chlorpheniramine; Dextromethorphan; Phenylephrine
      • Chlorpheniramine; Dihydrocodeine; Phenylephrine
      • Chlorpheniramine; Phenylephrine
      • Codeine; Phenylephrine; Promethazine
      • Dextromethorphan; Diphenhydramine; Phenylephrine
      • Dextromethorphan; Guaifenesin; Phenylephrine
      • Diclofenac; Misoprostol
      • Diphenhydramine; Phenylephrine
      • Ergonovine
      • General anesthetics
      • Guaifenesin; Phenylephrine
      • Methohexital
      • Methylergonovine
      • Midodrine
      • Misoprostol
      • Phenylephrine
      • Promethazine; Phenylephrine

      Level 3 (Moderate)

      • Articaine; Epinephrine
      • Bupivacaine; Epinephrine
      • Dopamine
      • Ephedrine
      • Ephedrine; Guaifenesin
      • Epinephrine
      • Lidocaine; Epinephrine
      • Norepinephrine
      • Prilocaine; Epinephrine
      • Succinylcholine
      Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Acetaminophen; Chlorpheniramine; Phenylephrine : (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Acetaminophen; Dextromethorphan; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Acetaminophen; Guaifenesin; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Articaine; Epinephrine: (Moderate) Oxytocin may potentiate the pressor effects of epinephrine. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal block anesthesia. [47239] [56575] Brompheniramine; Carbetapentane; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Brompheniramine; Dextromethorphan; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Brompheniramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Bupivacaine; Epinephrine: (Moderate) Oxytocin may potentiate the pressor effects of epinephrine. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal block anesthesia. [47239] [56575] Carbetapentane; Chlorpheniramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carbetapentane; Diphenhydramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carbetapentane; Guaifenesin; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carbetapentane; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carbetapentane; Phenylephrine; Pyrilamine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carbinoxamine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Carboprost Tromethamine: (Major) Carboprost tromethamine may augment the activity of other oxytocics. Augmentation can result in uterine hypertonus with subsequent uterine rupture, particularly in the absence of adequate cervical dilation. The concurrent use of carboprost tromethamine and other oxytocic drugs is not recommended. [9600] Chlorpheniramine; Dextromethorphan; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Chlorpheniramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Codeine; Phenylephrine; Promethazine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Dextromethorphan; Diphenhydramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Dextromethorphan; Guaifenesin; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Diclofenac; Misoprostol: (Major) In certain cases, oxytocin can be used in combination with other oxytocics for therapeutic purposes. However, in the augmentation of labor, oxytocin administration is usually withheld until after the last dose of intravaginal misoprostol. There is a risk of severe uterine hypertony occurring, with possible uterine rupture or cervical laceration when misoprostol and oxytocin are used at the same time. These products should be used concomitantly only under adequate supervision, with particular attention to ensure adequate cervical dilation has occurred. [29358] Dinoprostone, Prostaglandin E2: (Contraindicated) Dinoprostone is contraindicated in patients receiving intravenous oxytocic agents. Following dinoprostone use, a specific wash-out period is recommended before the use of oxytocin; see specific product information for the specific recommendations as they differ. These products should be used sequentially only under adequate obstetric supervision. Following the removal of the dinoprostone vaginal insert, an interval of at least 30 minutes is recommended prior to the use of another oxytocic agent. For the sequential use of oxytocin following dinoprostone gel administration, a dosing interval of 6 to 12 hours is recommended. Concomitant use of dinoprostone vaginal suppositories with other oxytocic agents is also not recommended. Serious side effects may occur if these agents are used concurrently. There is a risk of severe uterine hypertony occurring, with possible uterine rupture or cervical laceration. [41178] [41179] [47239] Diphenhydramine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Dopamine: (Moderate) Monitor blood pressure during concomitant use of dopamine and oxytocin due to the risk for severe hypertension. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal anesthesia. [47239] [66708] Ephedrine: (Moderate) Carefully monitor blood pressure in patients who have received ephedrine and oxytocin. Serious hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal anesthesia. Some patients have experienced a stroke. [47239] [60787] Ephedrine; Guaifenesin: (Moderate) Carefully monitor blood pressure in patients who have received ephedrine and oxytocin. Serious hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal anesthesia. Some patients have experienced a stroke. [47239] [60787] Epinephrine: (Moderate) Oxytocin may potentiate the pressor effects of epinephrine. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal block anesthesia. [47239] [56575] Ergonovine: (Major) Ergonovine and oxytocin both control uterine atony, and if used in combination there may be a risk of severe uterine hypertony, with possible uterine rupture or cervical laceration. [47239] General anesthetics: (Major) Adverse cardiovascular effects can develop as a result of concomitant administration of oxytocin with general anesthetics, especially in those with preexisting valvular heart disease. Cyclopropane, when administered with or without oxytocin, has been implicated in producing maternal sinus bradycardia, abnormal atrioventricular rhythms, hypotension, and increases in heart rate, cardiac output, and systemic venous return. In addition, halogenated anesthetics decrease uterine responsiveness to oxytocics (e.g., oxytocin) and, in high doses, can abolish it, increasing the risk of uterine hemorrhage. Halothane is a potent uterine relaxant. Enflurane displaces the myometrial response curve to oxytocin so that at lower concentrations of enflurane oxytocin will restore uterine contractions. However, as the dose of enflurane progresses (somewhere between 1.5 to 3% delivered enflurane) the response to oxytocin is inhibited. It is not clear if other halogenated anesthetics would interact with oxytocics in this manner. [5856] [5860] [5861] Guaifenesin; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Lidocaine; Epinephrine: (Moderate) Oxytocin may potentiate the pressor effects of epinephrine. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal block anesthesia. [47239] [56575] Methohexital: (Major) Adverse cardiovascular effects can develop as a result of concomitant administration of oxytocin with general anesthetics. [5856] [5861] Methylergonovine: (Major) Methylergonovine and oxytocin both control uterine atony, and if used in combination there may be a risk of severe uterine hypertony, with possible uterine rupture or cervical laceration. [47239] Midodrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjuction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [5861] Misoprostol: (Major) In certain cases, oxytocin can be used in combination with other oxytocics for therapeutic purposes. However, in the augmentation of labor, oxytocin administration is usually withheld until after the last dose of intravaginal misoprostol. There is a risk of severe uterine hypertony occurring, with possible uterine rupture or cervical laceration when misoprostol and oxytocin are used at the same time. These products should be used concomitantly only under adequate supervision, with particular attention to ensure adequate cervical dilation has occurred. [29358] Norepinephrine: (Moderate) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Prilocaine; Epinephrine: (Moderate) Oxytocin may potentiate the pressor effects of epinephrine. Severe hypertension has been reported when oxytocin was given 3 to 4 hours after prophylactic administration of a vasoconstrictor in conjunction with caudal block anesthesia. [47239] [56575] Promethazine; Phenylephrine: (Major) The administration of prophylactic vasopressors with oxytocin can cause severe, persistent hypertension, as the 2 drugs may have a synergistic and additive vasoconstrictive effect. This interaction was noted when oxytocin was given 3 to 4 hours after prophylactic vasoconstrictor in conjunction with caudal anesthesia. The incidence of such an interaction may be decreased if vasopressors are not administered prior to oxytocin. [47239] Succinylcholine: (Moderate) Concomitant use of succinylcholine and oxytocin may prolong neuromuscular blockade. [42039]
      Revision Date: 12/07/2022, 02:29:00 AM

      References

      5856 - Halothane, USP package insert. North Chicago, IL: Abbott Laboratories; 1998 Mar.5860 - Yamakage M, Tsujiguchi N, Chen X, et al. Sevoflurane inhibits contraction of uterine smooth muscle from pregnant rats similarly to halothane and isoflurane. Can J Anaesth 2002;49:62-6.5861 - Pitocin® (oxytocin injection, USP) package insert. Rochester, MI: Monarch Pharmaceuticals; 2003 Jan.9600 - Hemabate (carboprost tromethamine injection, USP) package insert. New York, NY: Pfizer, Inc.; 2013 Dec.29358 - Cytotec (misoprostol) package insert. New York, NY: G.D. Searle LLC; Co.; 2018 Feb.41178 - Cervidil (dinoprostone) vaginal insert package insert. Parsippany, NJ, Ferring Pharmaceuticals, Inc.; 2020 Jan.41179 - Prepidil Gel (dinoprostone) cervical gel package insert. New York, NY: Pfizer Inc.; 2019 Dec.42039 - Quelicin (succinylcholine) injection package insert. Lake Forest, IL: Hospira, Inc.; 2022 Nov.47239 - Pitocin (oxytocin injection) package insert. Chestnut Ridge, NY; Par Pharmaceutical, Inc.: 2021 May.56575 - Adrenalin (epinephrine) 1 mg/mL injection package insert. Chestnut Ridge, NJ: Par Pharmaceutical Companies, Inc.; 2022 Jun.60787 - Akovaz (ephedrine sulfate injection) package insert. Lenoir, NC: Exela Pharma Sciences, LLC; 2021 Apr.66708 - Dopamine hydrochloride in dextrose injection package insert. Lake Forest, IL: Pfizer, Inc; 2021 Apr.

      Monitoring Parameters

      • laboratory monitoring not necessary

      US Drug Names

      • Pitocin
      ;