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OXYTOCIN

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Classification   |    Detailed evidence-based information

Substances Included Synonyms

Therapeutic Toxic Class

    A) Oxytocin is a cyclic nonpeptide hormone secreted by the hypothalamus and stored in the posterior lobe of the pituitary gland. It has uterine stimulant properties, and is either prepared from the gland of mammals or by synthesis.

Specific Substances

    1) Alpha-hypophamine
    2) Hipofamina
    3) Ocitocina
    4) Ocytocine
    5) Oksitocinas
    6) Oksitosiini
    7) Oksitosin
    8) Oksytocyna
    9) Ossitocina
    10) Oxitocin
    11) Oxitocina
    12) Oxytocine
    13) Oxytocinum
    14) Oxytosin
    15) CAS 50-56-6

Available Forms Sources

    A) FORMS
    1) Oxytocin is available in the United States as 10 Units/mL solution for intravenous infusion or intramuscular injection (Prod Info Pitocin(R) IV, IM injection, 2011).
    2) Novartis Pharmaceuticals removed Syntocinon(R) nasal spray from the market March 1995. The data in this evaluation are included for completeness only (Pers Comm, 2000).
    B) USES
    1) Oxytocin is used to induce or augment labor and to control postpartum uterine bleeding or hemorrhage. It is also indicated for adjunctive therapy in the management of incomplete or inevitable abortion (Prod Info Pitocin(R) IV, IM injection, 2011).

Overview

Life Support

    A) This overview assumes that basic life support measures have been instituted.

Clinical Effects

    0.2.1) SUMMARY OF EXPOSURE
    A) USES: Oxytocin is used to induce or augment labor and to control postpartum uterine bleeding or hemorrhage. It is also indicated for adjunctive therapy in the management of incomplete or inevitable abortion.
    B) PHARMACOLOGY: The uterine myometrium contains receptors specific to oxytocin. Oxytocin promotes uterine contractions by increasing intracellular concentrations of calcium in uterine myometrial tissue, thereby increasing the activity of the calcium-dependent phosphorylating enzyme myosin light-chain kinase. The effect is greatest during early labor at term due to the oxytocin receptor concentration which increases during pregnancy and peaks at term.
    C) TOXICOLOGY: Oxytocin has anti-diuretic effects and can cause hyponatremia in overdose. Large doses of oxytocin can cause excessive uterine contractions in pregnant women. It as a minimal effect on the uterus except near the end of pregnancy and midcycle of a woman's menstrual cycle.
    D) EPIDEMIOLOGY: Overdose is rare.
    E) WITH THERAPEUTIC USE
    1) The following adverse effects have been reported: nausea, vomiting, blood pressure changes (hypotension followed by a hypertensive period), water intoxication, hyponatremia (following continuous IV infusion), arteriospasm, cardiac dysrhythmias, premature ventricular contractions, seizures (secondary to water intoxication), fatal afibrinogenemia, headache, flushing, blurred vision and conjunctival hemorrhages, memory dysfunction, subarachnoid hemorrhage, postpartum hemorrhage, and anaphylactic reaction.
    2) Excessive dosage or allergic reaction can cause uterine hypertonicity, spasm, tetanic contraction, or rupture of the uterus. Severe water intoxication with seizures and coma have been reported with a slow oxytocin infusion over a 24-hour period.
    3) FETUS OR NEONATE: Bradycardia, premature ventricular contractions and other dysrhythmias, permanent CNS or brain damage, fetal death, and neonatal seizures have been reported due to induced uterine motility. Neonatal jaundice, retinal hemorrhage, and low apgar scores (at 5 minutes) have been reported after maternal use.
    F) WITH POISONING/EXPOSURE
    1) MILD TO MODERATE TOXICITY: Overdose effects are anticipated to be an extension of adverse effects observed following therapeutic doses. Excessive dosage can cause uterine hypertonicity, spasm, and tetanic contraction. Extreme changes in blood pressure may be observed following administration of oxytocin, especially if given mistakenly as an intravenous bolus. Inadvertent oxytocin epidural administration has been reported; transient hypertension was the only adverse effect noted.
    2) SEVERE TOXICITY: Severe effects include uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, uteroplacental hypoperfusion, variable deceleration of fetal heart, fetal hypoxia, hypercapnia, or death. Antidiuretic effect of oxytocin can cause water intoxication with seizures, which can occur following large doses (40 to 50 milliunits/min) of oxytocin infused for long periods.
    3) A woman developed severe hypotension and water intoxication after receiving a very large intravenous bolus injection of oxytocin instead of a continuous infusion.
    0.2.3) VITAL SIGNS
    A) WITH THERAPEUTIC USE
    1) Hypotension may occur.
    0.2.20) REPRODUCTIVE
    A) Oxytocin is classified as FDA pregnancy category C.
    B) Conventional dosing techniques of oxytocin have not been associated with teratogenicity.
    C) The use of oxytocin to induce labor may result in intrauterine transplacental hyponatremia which may cause neonatal seizures and respiratory depression.
    D) The incidence of neonatal hyperbilirubinemia is also increased following oxytocin induced labor when compared to spontaneous labor.
    E) Uterine rupture or tears may occur following oxytocin use, with grand multiparas being the highest risk.
    F) The use of oxytocin to induce labor has resulted in uterine hypertonus. Hypercontractility may lead to tetanic contractions that may last form 10 to 20 minutes after the oxytocin has been withdrawn.
    0.2.21) CARCINOGENICITY
    A) At the time of this review, no data were available to assess the carcinogenic potential of this agent.

Laboratory Monitoring

    A) Monitor vital signs and mental status.
    B) Monitor serum electrolytes, especially sodium, to check for hyponatremia and water intoxication.
    C) A CBC, INR, and PTT should be ordered in cases of excessive vaginal bleeding.
    D) Monitor urine volume and osmolality to check for water intoxication.
    E) Obtain an ECG and institute continuous cardiac monitoring following significant exposures.
    F) The use of oxytocin to induce labor has been associated with an increased incidence of neonatal jaundice. However, this may be the result of labor induction rather than a direct effect of the drug. Monitor bilirubin.
    G) Monitor the fetus (ultrasound, fetal heart rate, and tocographic monitoring) following an overdose.

Treatment Overview

    0.4.4) EYE EXPOSURE
    A) DECONTAMINATION: Remove contact lenses and irrigate exposed eyes with copious amounts of room temperature 0.9% saline or water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist after 15 minutes of irrigation, the patient should be seen in a healthcare facility.
    0.4.5) DERMAL EXPOSURE
    A) OVERVIEW
    1) DECONTAMINATION: Remove contaminated clothing and jewelry and place them in plastic bags. Wash exposed areas with soap and water for 10 to 15 minutes with gentle sponging to avoid skin breakdown. A physician may need to examine the area if irritation or pain persists (Burgess et al, 1999).
    0.4.6) PARENTERAL EXPOSURE
    A) MANAGEMENT OF MILD TO MODERATE TOXICITY
    1) Treatment is primarily symptomatic and supportive. Treat mild hyponatremia with water restriction and/or 0.9% sodium chloride.
    B) MANAGEMENT OF SEVERE TOXICITY
    1) Manage severe hyponatremia with 0.9% sodium chloride; 3% sodium chloride may be necessary only with very serious toxicity. Treat seizures with benzodiazepines; recurrent seizures may require the addition of barbiturates or propofol. Consultation should be made with obstetrics and gynecology in cases of uterine hypertonicity or bleeding after use.
    C) DECONTAMINATION
    1) Gastrointestinal decontamination is not required as oxytocin is administered intravenously or intramuscularly.
    D) AIRWAY MANAGEMENT
    1) Endotracheal intubation and mechanical ventilation may be necessary if recurrent seizures secondary to hyponatremia develop.
    E) ANTIDOTE
    1) None.
    F) SEIZURES
    1) Administer IV benzodiazepines; barbiturates or propofol may be needed if seizures persist or recur.
    G) HYPOTENSION
    1) Hypotension followed by a hypertensive period may occur. Administer normal saline 10 to 20 mL/kg. Add dopamine or norepinephrine if unresponsive to fluids.
    H) HYPERTENSION
    1) For mild/moderate asymptomatic hypertension (no end organ damage), pharmacologic treatment is generally not necessary. For severe hypertension, nitroprusside is preferred. Labetalol, nitroglycerin, and phentolamine are alternatives.
    I) HYPONATREMIA
    1) Evaluate for hyponatremia and associated symptoms. Patients with mild symptoms can be managed with water restriction. Promote diuresis. Correct electrolyte imbalances and treat seizures. Patients with moderate to severe symptoms should receive 0.9% sodium chloride (rarely 3% NaCl in patients with very severe symptoms). The goal is slow correction; the serum sodium should not increase more than 2 mEq/L/hour in any 4-hour period or more than 15 mEq/L per day. Rapid correction may cause central pontine myelinolysis. Monitor serum electrolytes, fluid intake and output, and urine volume and electrolytes.
    J) ENHANCED ELIMINATION
    1) The effectiveness of hemodialysis following oxytocin overdose is unknown. Hemodialysis is probably not required as oxytocin is rapidly removed from plasma through the kidney and the liver.
    K) PATIENT DISPOSITION
    1) HOME CRITERIA:There is no data to support home management, and oxytocin is generally only used in the hospital setting. .
    2) OBSERVATION CRITERIA: Any patient with symptoms should be observed with frequent monitoring of vital signs.
    3) ADMISSION CRITERIA: Patients with significant symptoms and/or abnormal vital signs should be admitted. Pregnant patients with symptoms of vaginal bleeding or contractions should be evaluated by an obstetrician/gynecologist.
    4) CONSULT CRITERIA: Consult a poison center or medical toxicologist for assistance in managing patients with severe toxicity or in whom the diagnosis is not clear. Obstetrician/gynecologist should be consulted for any case of excessive uterine bleeding or contractions and in the case of inadvertent administration to a pregnant woman.
    L) PITFALLS
    1) Falsely attributing patient's symptoms to oxytocin when the true underlying cause is due to another etiology. Concomitant therapy that may increase bleeding risk (eg, LMWHs). When managing a suspected overdose of oxytocin, the possibility of multidrug involvement should be considered.
    M) PHARMACOKINETICS
    1) Following intramuscular injection, uterine response occurs within 3 to 5 minutes and persists for 2 to 3 hours. Distributed throughout the extracellular fluid and small amounts probably reach the fetal circulation. Rapidly metabolized in the liver, kidney, and lactating mammary gland. Only very small amounts of unchanged oxytocin are detectable in the urine.
    N) DIFFERENTIAL DIAGNOSIS
    1) Spontaneous abortion, spontaneous labor.

Range Of Toxicity

    A) TOXICITY: Antidiuretic effect of oxytocin can cause water intoxication with seizures, which can occur following large doses (40 to 50 milliunits/min) of oxytocin infused for long periods. A pregnant woman developed severe hypotension and water intoxication after receiving a very large intravenous bolus injection of oxytocin (a bolus of 25 Units of oxytocin instead of a continuous infusion of diluted oxytocin). She recovered after supportive therapy. Five cases of inadvertent epidural administration of oxytocin (0.04 to 5 IU in 4 cases and 10 mL (unknown dose and diluent) in another case) have been reported. Transient hypertension developed in one patient, in the others, no immediate adverse effects were observed.
    B) THERAPEUTIC DOSE: Induction of labor - medically indicated: 0.5 to 1 milliunit/min IV (3 to 6 mL/hr of a 10 units/1000 mL dilute oxytocin solution); gradually increase dose in increments of 1 to 2 milliunits/min every 30 to 60 min. Midtrimester elective abortion: 10 to 20 milliunits/min (20 to 40 drops/min) IV; MAX dose 30 units/12 hr. Postpartum hemorrhage: IV: 10 to 40 units of oxytocin IV infusion (MAX: 40 units to 1000 mL IV solution). IM: 10 units IM given after delivery of the placenta. CHILDREN: Oxytocin is not used in children.

Clinical Effects

Summary Of Exposure

    A) USES: Oxytocin is used to induce or augment labor and to control postpartum uterine bleeding or hemorrhage. It is also indicated for adjunctive therapy in the management of incomplete or inevitable abortion.
    B) PHARMACOLOGY: The uterine myometrium contains receptors specific to oxytocin. Oxytocin promotes uterine contractions by increasing intracellular concentrations of calcium in uterine myometrial tissue, thereby increasing the activity of the calcium-dependent phosphorylating enzyme myosin light-chain kinase. The effect is greatest during early labor at term due to the oxytocin receptor concentration which increases during pregnancy and peaks at term.
    C) TOXICOLOGY: Oxytocin has anti-diuretic effects and can cause hyponatremia in overdose. Large doses of oxytocin can cause excessive uterine contractions in pregnant women. It as a minimal effect on the uterus except near the end of pregnancy and midcycle of a woman's menstrual cycle.
    D) EPIDEMIOLOGY: Overdose is rare.
    E) WITH THERAPEUTIC USE
    1) The following adverse effects have been reported: nausea, vomiting, blood pressure changes (hypotension followed by a hypertensive period), water intoxication, hyponatremia (following continuous IV infusion), arteriospasm, cardiac dysrhythmias, premature ventricular contractions, seizures (secondary to water intoxication), fatal afibrinogenemia, headache, flushing, blurred vision and conjunctival hemorrhages, memory dysfunction, subarachnoid hemorrhage, postpartum hemorrhage, and anaphylactic reaction.
    2) Excessive dosage or allergic reaction can cause uterine hypertonicity, spasm, tetanic contraction, or rupture of the uterus. Severe water intoxication with seizures and coma have been reported with a slow oxytocin infusion over a 24-hour period.
    3) FETUS OR NEONATE: Bradycardia, premature ventricular contractions and other dysrhythmias, permanent CNS or brain damage, fetal death, and neonatal seizures have been reported due to induced uterine motility. Neonatal jaundice, retinal hemorrhage, and low apgar scores (at 5 minutes) have been reported after maternal use.
    F) WITH POISONING/EXPOSURE
    1) MILD TO MODERATE TOXICITY: Overdose effects are anticipated to be an extension of adverse effects observed following therapeutic doses. Excessive dosage can cause uterine hypertonicity, spasm, and tetanic contraction. Extreme changes in blood pressure may be observed following administration of oxytocin, especially if given mistakenly as an intravenous bolus. Inadvertent oxytocin epidural administration has been reported; transient hypertension was the only adverse effect noted.
    2) SEVERE TOXICITY: Severe effects include uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, uteroplacental hypoperfusion, variable deceleration of fetal heart, fetal hypoxia, hypercapnia, or death. Antidiuretic effect of oxytocin can cause water intoxication with seizures, which can occur following large doses (40 to 50 milliunits/min) of oxytocin infused for long periods.
    3) A woman developed severe hypotension and water intoxication after receiving a very large intravenous bolus injection of oxytocin instead of a continuous infusion.

Vital Signs

    3.3.1) SUMMARY
    A) WITH THERAPEUTIC USE
    1) Hypotension may occur.
    3.3.4) BLOOD PRESSURE
    A) WITH THERAPEUTIC USE
    1) HYPOTENSION has been reported following oxytocin use (Maycock & Russell, 1993; (Morriss et al, 1994).

Heent

    3.4.3) EYES
    A) WITH THERAPEUTIC USE
    1) BLURRED VISION
    a) Blurred vision and conjunctival hemorrhage are rare complications, and has been seen in cases of oxytocin induced water intoxication (Storch, 1977).
    B) WITH POISONING/EXPOSURE
    1) OCULAR BLEEDING
    a) Oxytocin has been loosely associated with retinal hemorrhages in newborns following labor induction.
    1) One study compared the incidence of retinal hemorrhages in neonates with labors induced by oxytocin or the prostaglandin, dinoprostone.
    2) The occurrence of ocular bleeding was significantly higher in the dinoprostone group, which suggests retinal hemorrhaging is mediated by prostaglandins.
    3) The existence of bleeding in neonates exposed to oxytocin may be explained by the presence of endogenous prostaglandins that are necessary to ripen the uterus, allowing oxytocin to be effective (Schoenfeld et al, 1985).

Cardiovascular

    3.5.2) CLINICAL EFFECTS
    A) ABNORMAL BLOOD PRESSURE
    1) WITH THERAPEUTIC USE
    a) The cardiovascular effects of oxytocin used postpartum consist of hypotension followed by a hypertensive period.
    1) Administration of 0.1 mcg/kg body weight of oxytocin produced no less than a 46% decrease in arterial blood pressure.
    2) Extreme changes in blood pressure may be observed following administration of oxytocin, especially if given mistakenly as an intravenous bolus (Haeri et al, 1976; Hendricks & Brenner, 1970; Johnstone, 1972).
    2) WITH POISONING/EXPOSURE
    a) Extreme changes in blood pressure may be observed following administration of oxytocin, especially if given mistakenly as an intravenous bolus (Haeri et al, 1976; Hendricks & Brenner, 1970; Johnstone, 1972).
    b) CASE REPORT: After delivering an infant during cesarean section, a 32-year-old morbidly obese pregnant woman developed severe hypotension (BP 68/34 mm Hg) and water intoxication after receiving an intravenous bolus injection of oxytocin 5 Units of oxytocin, carbetocin 100 mcg, and midazolam 4 mg, followed by another bolus of 25 Units of oxytocin instead of a continuous infusion of diluted oxytocin. She also received 1 L of Hartman's solution and 500 mL of colloid solution. Laboratory analysis revealed plasma sodium of 118 mmol/L and potassium of 3.9 mmol/L, measured just before the end of anesthesia. Initially, she was diagnosed as having an amniotic fluid embolism (AFE), however, she did not show typical clinical manifestations of AFE (eg, coagulopathy, uterine atony, seizures, cardiac arrest, pulmonary edema). At this time, the medication error was identified. Following supportive therapy, including vasopressors, Lasix 20 mg, 0.9% normal saline, and 25% mannitol, she recovered gradually over the next 6 hours (In et al, 2011).
    B) MYOCARDIAL INFARCTION
    1) WITH THERAPEUTIC USE
    a) CASE REPORT: One source reported the death of a 29-year-old pregnant woman with congenital aortic stenosis who was administered oxytocin parenterally during therapeutic abortion. Autopsy revealed an extensive myocardial infarction (Robinson et al, 1967).
    C) CONDUCTION DISORDER OF THE HEART
    1) WITH THERAPEUTIC USE
    a) Cardiac dysrhythmias and premature ventricular contractions have been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    2) WITH POISONING/EXPOSURE
    a) Alterations in fetal heart rate, usually bradycardia, have been reported upon administration of oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011; Chung, 1966; Clegg, 1974; Mofid & Roux, 1976; Noriega-Guerra, 1966).
    D) ARTERIOSPASM
    1) WITH THERAPEUTIC USE
    a) Arteriospasm may occur after oxytocin use. In one parturient patient, imminent gangrene was noted (Evron et al, 1986).

Respiratory

    3.6.2) CLINICAL EFFECTS
    A) ACUTE LUNG INJURY
    1) WITH THERAPEUTIC USE
    a) Pulmonary edema, most often associated with water intoxication, has been associated with the therapeutic use of oxytocin (Shahin & Guharoy, 1991).

Neurologic

    3.7.2) CLINICAL EFFECTS
    A) SEIZURE
    1) WITH THERAPEUTIC USE
    a) Seizure-like episodes have been reported following administration of oxytocin. Water intoxication is a probable cause of seizures (Prod Info Pitocin(R) IV, IM injection, 2011; Wang et al, 2000) Sederbreg-Olsen & Olsen, 1983; (Lafay-Pillet et al, 1987; Burnett et al, 1975; Kaplan, 1978; Pedlow, 1970; McKenna & Shaw, 1979; Mayer-Hubner, 1996).
    B) HEADACHE
    1) WITH THERAPEUTIC USE
    a) Headache is a commonly reported side effect following administration of oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011; Coltart & Coe, 1975; Craft & Musa, 1971) Toaff et al, 1971; (Wajntraub, 1966).
    C) AMNESIA
    1) WITH THERAPEUTIC USE
    a) In a postmortem study of 12 confirmed Alzheimer cases, the concentration of oxytocin was elevated in the hippocampus and temporal cortex in Alzheimer patients compared with 13 controls (Mazurek et al, 1987).
    b) In another study, 6 healthy volunteers were administered oxytocin in a double-blind, crossover fashion and then subjected to cognitive function tests. The oxytocin-treated patients did not exhibit learning deficits, but demonstrated a significant impairment of memory recall (Kovacs & Telegdy, 1982).
    D) SUBARACHNOID HEMORRHAGE
    1) WITH THERAPEUTIC USE
    a) Subarachnoid has been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    b) CASE REPORT: Curless & Beaumont (1990) reported a case of subarachnoid hemorrhage during an oxytocin assisted labor that mimicked an acute water intoxication, and delayed the diagnosis of the hemorrhage (Curless et al, 1990).
    E) TOXIC ENCEPHALOPATHY
    1) WITH POISONING/EXPOSURE
    a) CASE REPORT: A 33-year-old woman, drinking more than 5 liters of herbal tea each day and using oxytocin nasal spray 8 times a day while breastfeeding, experienced a generalized seizure, somnolence, disorientation, and vomiting. Hyponatremia was reported, which subsequently led to the diagnosis of hypo- osmolar encephalopathy (Mayer-Hubner, 1996).
    F) COMA
    1) WITH THERAPEUTIC USE
    a) CASE REPORT: A 22-year-old woman experienced a generalized seizure and became comatose secondary to water intoxication (serum sodium 15 mmol/L) following administration of an intravenous oxytocin infusion for an abortion induction. The patient regained consciousness after 3 hours of spontaneous diuresis (Wang et al, 2000).

Gastrointestinal

    3.8.2) CLINICAL EFFECTS
    A) NAUSEA AND VOMITING
    1) WITH THERAPEUTIC USE
    a) Nausea and vomiting are commonly reported adverse effects following administration of oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011; Miller, 1975; Murray & Clinch, 1975).

Hepatic

    3.9.2) CLINICAL EFFECTS
    A) HYPERBILIRUBINEMIA
    1) WITH POISONING/EXPOSURE
    a) The risk of neonatal hyperbilirubinemia appears to be about 1.6 times greater following oxytocin-induced labor than that following spontaneous labor (Beazley & Alderman, 1975a; Boylan, 1976; Chew & Swann, 1976; Pavlou, 1978; Sims & Neligan, 1975; Singhi & Singh, 1977; Wynne et al, 1975; Schwartz & Jones, 1978; Smith & Wilson, 1978).
    b) Beazley & Alderman (1975) studied the relationship between the total dose of oxytocin received by 815 patients and the development of hyperbilirubinemia in infants. The proportion of babies who developed hyperbilirubinemia increased in direct relation to the total dose of oxytocin received (Beazley & Alderman, 1975).

Genitourinary

    3.10.2) CLINICAL EFFECTS
    A) PERFORATION OF UTERUS
    1) WITH THERAPEUTIC USE
    a) Uterine rupture or tears may occur following oxytocin use, with grand multiparas being the highest risk (Daw, 1973; Horwitz, 1974; Peyser & Toaff, 1972; Propping, 1977; Sanchez et al, 1991).
    b) Propping et al (1977) report uterine rupture in 2 women, 34 and 37 years old, following high dose oxytocin (24 to 240 mU/min) and prostaglandin therapy. Abdominal hysterectomies were then performed on both women (Propping, 1977).
    2) WITH POISONING/EXPOSURE
    a) Excessive dosage or allergic reaction can cause uterine hypertonicity, spasm, tetanic contraction, or rupture of the uterus (Prod Info Pitocin(R) IV, IM injection, 2011).
    b) Overdose of oxytocin can lead to tumultuous labor, uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, and uteroplacental hypoperfusion (Prod Info Pitocin(R) IV, IM injection, 2011).
    B) CERVICAL LACERATION
    1) WITH POISONING/EXPOSURE
    a) Overdose of oxytocin can lead to tumultuous labor, uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, and uteroplacental hypoperfusion (Prod Info Pitocin(R) IV, IM injection, 2011).
    C) TETANIC CONTRACTIONS OF UTERUS
    1) WITH THERAPEUTIC USE
    a) The use of oxytocin to induce labor has resulted in uterine hypertonus. Hypercontractility may lead to tetanic contractions that may last from 10 to 20 minutes after the oxytocin has been withdrawn. Large, rapid doses may induce hypertonicity not responsive to discontinuation of therapy (Kruse, 1986).
    2) WITH POISONING/EXPOSURE
    a) Excessive dosage or allergic reaction can cause uterine hypertonicity, spasm, tetanic contraction, or rupture of the uterus (Prod Info Pitocin(R) IV, IM injection, 2011).
    b) EPIDURAL ADMINISTRATION: A 20-year-old pregnant woman (41 weeks of gestation) who was undergoing cesarean delivery after maximal oxytocin therapy, inadvertently received 5 International Units of oxytocin infused into an epidural catheter. At this time, no fluid could be aspirated from the epidural catheter. Persistent uterine atony was treated with an additional dose of (5 IU) oxytocin administered intravenously. Despite an estimated blood loss of 1200 mL, she remained stable during surgery. On follow-up visits, she had no sequelae from epidural oxytocin administration. Four additional cases of inadvertent oxytocin epidural administration (0.04 to 0.8 IU in 3 cases and 10 mL (unknown dose and diluent) in another case) have been reported. Transient hypertension developed in one patient, in the others no immediate adverse effects were observed (Ross & Wise, 2012).

Hematologic

    3.13.2) CLINICAL EFFECTS
    A) AFIBRINOGENEMIA
    1) WITH THERAPEUTIC USE
    a) Fatal afibrinogenemia has been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    B) POSTPARTUM HEMORRHAGE
    1) WITH THERAPEUTIC USE
    a) Postpartum hemorrhage has been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    2) WITH POISONING/EXPOSURE
    a) Overdose of oxytocin can lead to tumultuous labor, uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, and uteroplacental hypoperfusion (Prod Info Pitocin(R) IV, IM injection, 2011).

Dermatologic

    3.14.2) CLINICAL EFFECTS
    A) FLUSHING
    1) WITH THERAPEUTIC USE
    a) Flushing has been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    b) Flushing may occur if oxytocin is given in large amounts (Kitchin et al, 1986).

Endocrine

    3.16.2) CLINICAL EFFECTS
    A) ABNORMAL ANTI-DIURETIC HORMONE
    1) WITH THERAPEUTIC USE
    a) The antidiuretic effect of oxytocin is measurable at an infusion rate of 15 mU/min and is reported to be maximal at 45 mU/min.
    1) Antidiuresis appears to be initiated by the direct action of oxytocin on the kidney and not as a result of any stimulation of the release of antidiuretic hormone (ie, SIADH). The action of the drug stimulates renal tubular absorption of free water.
    b) One study reported that the administration of a single large dose of oxytocin does not effect renal urine flow. Patients receiving continuous IV infusion of oxytocin should be monitored closely and at the first sign of water retention, the drug and heavy fluids should be discontinued (Self, 1966).

Immunologic

    3.19.2) CLINICAL EFFECTS
    A) ANAPHYLACTOID REACTION
    1) WITH THERAPEUTIC USE
    a) Anaphylactic reaction has been reported in patients receiving oxytocin (Prod Info Pitocin(R) IV, IM injection, 2011).
    b) CASE REPORT: An anaphylactoid reaction to oxytocin occurred in a 27-year-old woman undergoing emergency Cesarean section. Following delivery, synthetic oxytocin 10 units was administered intravenously, resulting in hypotension and erythema of the face and limbs. A second episode occurred in the patient's second pregnancy; severe itching and urticaria of the upper body with a reduction of systolic arterial pressure to 260 mm Hg occurred following 5 mg intravenous oxytocin. Chest tightness was also observed but there was no clinical evidence of bronchospasm. Recovery in both instances was uneventful with symptomatic and supportive therapy (Slater et al, 1985).
    c) CASE REPORT: An anaphylactoid reaction was described in a 27-year-old woman during cesarean section following administration of oxytocin. Following delivery, synthetic oxytocin 5 units was given directly into the myometrium at several places, with another 5 mg being added to an IV infusion bottle. Numbness of the mouth and extremities was observed within minutes, followed by chest tightness and perioral and periorbital erythema and edema. Systolic blood pressure decreased from 110 to 70 mm Hg and was treated successfully with etilefrine 2 mg. The patient subsequently developed whole body urticaria and another drop in systolic pressure, which was unresponsive to ephedrine 20 mg and hydrocortisone 0.5 g IV. Epinephrine 0.05 mg resulted in recovery of blood pressure. A subsequent intradermal skin test (0.02 mL oxytocin, 5 units/mL) demonstrated a positive reaction (Kawarabayashi et al, 1988).
    1) Anaphylactoid reactions to oxytocin appear to be rare, although other cases have been described in the literature (Emmott, 1990; Giuffrida et al, 1981; Slater et al, 1986).
    d) CASE REPORT: Hofmann et al (1986) described a case of anaphylactic shock in a 34-year-old who received oxytocin preserved with chlorobutanol. The patient was allergic to chlorobutanol (Hofmann et al, 1986).
    e) CASE REPORT: A 29-year-old woman developed an anaphylactoid reaction, consisting of dyspnea, dry cough, and mild hypotension, 8 minutes after receiving IV oxytocin. The patient became severely cyanotic within 2 to 3 minutes of initial development of dyspnea. Symptoms completely resolved following supportive care (Morriss et al, 1994).

Reproductive

    3.20.1) SUMMARY
    A) Oxytocin is classified as FDA pregnancy category C.
    B) Conventional dosing techniques of oxytocin have not been associated with teratogenicity.
    C) The use of oxytocin to induce labor may result in intrauterine transplacental hyponatremia which may cause neonatal seizures and respiratory depression.
    D) The incidence of neonatal hyperbilirubinemia is also increased following oxytocin induced labor when compared to spontaneous labor.
    E) Uterine rupture or tears may occur following oxytocin use, with grand multiparas being the highest risk.
    F) The use of oxytocin to induce labor has resulted in uterine hypertonus. Hypercontractility may lead to tetanic contractions that may last form 10 to 20 minutes after the oxytocin has been withdrawn.
    3.20.2) TERATOGENICITY
    A) LACK OF EFFECT
    1) Conventional dosing techniques of oxytocin have not been associated with teratogenicity (Schardein, 1976).
    3.20.3) EFFECTS IN PREGNANCY
    A) PREGNANCY CATEGORY
    1) The manufacturer has classified oxytocin as FDA pregnancy category C (Prod Info Oxytocin intramuscular injection, intravenous injection, 2006).
    B) ADVERSE REACTIONS
    1) Bradycardia, premature ventricular contractions and other dysrhythmias, permanent CNS or brain damage, and fetal death have been reported in the fetus and neonates due to oxytocin-induced uterine mobility. Neonatal retinal hemorrhage, low apgar scores, and jaundice have also been reported following the use of oxytocin in the mother (Prod Info Oxytocin intramuscular injection, intravenous injection, 2006).
    C) PLACENTAL BARRIER
    1) The use of oxytocin to induce labor may result in intrauterine transplacental hyponatremia which may cause neonatal seizures and respiratory depression (Schwartz & Jones, 1978). The combination of intravenous fluids and oxytocin therapy results in a depression of cord sodium levels. Symptomatic hyponatremia has been reported. Maternal and cord sodium levels are closely correlated, which is consistent with passive diffusion of sodium across the placenta. To avoid neonatal and maternal hyponatremia, fluids containing sodium are suggested for continuous infusion of oxytocin (Spencer et al, 1981).
    2) The oxytocin challenge test used to identify and follow the fetus at risk for utero placental insufficiency does not appear to increase the incidence of premature birth or premature rupture of the membranes. Of 389 patients undergoing the oxytocin challenge test prior to 38 weeks gestation, 6.7% underwent delivery after spontaneous onset of premature labor within five days of the test. This incidence, however, did not exceed the incidence of spontaneous delivery prior to 38 weeks (7.5%) in patients not undergoing the oxytocin challenge test or the incidence of premature delivery and spontaneous onset of labor in patients undergoing the nonstress test (7.6%). The occurrence of premature labor following the oxytocin challenge test was not greater during the two days after the test when compared to the third and fourth days following the test. This is also consistent with the idea that the oxytocin challenge test does not present an increased risk of premature labor (Braly et al, 1981).
    D) BILIRUBINEMIA
    1) The incidence of neonatal hyperbilirubinemia is also increased following oxytocin induced labor when compared to spontaneous labor. In one study, a high correlation existed between the total amount of oxytocin administered and the incidence of neonatal hyperbilirubinemia (Beazley & Alderman, 1975). In another study, neonatal jaundice was correlated well with fetal maturity rather than the use of oxytocin (Lange et al, 1982)
    E) UTERINE PERFORATION
    1) Use of oxytocin in grand multipara is considered hazardous and is discouraged since it can result in uterine rupture or tears. Grand multiparas are a significant risk when high-dose oxytocin is administered after prostaglandins (Daw, 1973; Horwitz, 1974; Peyser & Toaff, 1972; Propping, 1977; Sanchez et al, 1991; Lurie et al, 1993).
    2) Uterine rupture in 2 women (34 and 37 years of age) after high-dose oxytocin (24 to 240 mU/min) was added following prostaglandins. Abdominal hysterectomies had to be performed on both women (Propping, 1977).
    F) HYPERTONIA
    1) The use of oxytocin to induce labor has resulted in uterine hypertonus. If oxytocin was administered as a gradually increasing intravenous infusion, the hyperstimulation of the uterus usually is reversed by discontinuing oxytocin administration. Large, rapid doses of oxytocin may induce hypertonicity not responsive to discontinuation of therapy. Hypercontractility may lead to tetanic contractions that may last from 10 to 20 minutes after the oxytocin has been withdrawn (Kruse, 1986).
    G) HEPATIC NECROSIS
    1) A full-term infant developed severe hepatic necrosis following a maternal overdose of IV oxytocin (17,300 mUnits over 20 minutes). Life support for the infant was withdrawn on the fourth postnatal day, and an autopsy revealed massive hepatic infarction, diffuse alveolar damage, and periventricular leukomalacia (Robichaux & Perper, 1992).
    H) PERINATAL DISORDER
    1) One hundred deliveries were compared using oxytocin with 100 which did not. It was found that newborns had lower Apgar scores, remained in the incubator longer, and had a higher rate of respiratory complications and jaundice if their mothers had received oxytocin. Sanchez et al (1991)
    I) OVERDOSE
    1) Overdose of oxytocin can lead to tumultuous labor, uterine rupture, cervical and/or vaginal lacerations, hemorrhaging, uteroplacental hypoperfusion, variable deceleration of fetal hear, fetal hypoxia, hypercapnia, or death. Large doses of oxytocin (40 to 50 milliunits/min) administered over a long period of time can cause an inherent antidiuretic effect which can lead to water intoxication with convulsions (Prod Info Oxytocin intramuscular injection, intravenous injection, 2006).
    3.20.4) EFFECTS DURING BREAST-FEEDING
    A) LACK OF EFFECT
    1) BREAST MILK
    a) A randomized, double-blind trial comparing oxytocin nasal spray with placebo determined that the use of oxytocin spray did not significantly increase total breast milk production during the first five days postpartum. Mothers who had delivered an infant at less than 35 weeks' gestation were randomized to each group; complete 5-day milk records were available for 21 mothers in each group. Two to five minutes before expressing milk from each breast with a breast pump, each mother administered 1 spray (100 microliter of 40 international units synthetic oxytocin per mL or normal saline). They were to express milk every 3 hours, and record the time and weight of milk. While there was some evidence that oxytocin use increased the amount of milk expressed during the first two days, by 5 days postpartum the women in the placebo group were producing greater amounts (Fewtrell et al, 2006).

Carcinogenicity

    3.21.2) SUMMARY/HUMAN
    A) At the time of this review, no data were available to assess the carcinogenic potential of this agent.
    3.21.3) HUMAN STUDIES
    A) LACK OF INFORMATION
    1) At the time of this review, no data were available to assess the carcinogenic potential of this agent.

Laboratory Monitoring

Monitoring Parameters Levels

    4.1.1) SUMMARY
    A) Monitor vital signs and mental status.
    B) Monitor serum electrolytes, especially sodium, to check for hyponatremia and water intoxication.
    C) A CBC, INR, and PTT should be ordered in cases of excessive vaginal bleeding.
    D) Monitor urine volume and osmolality to check for water intoxication.
    E) Obtain an ECG and institute continuous cardiac monitoring following significant exposures.
    F) The use of oxytocin to induce labor has been associated with an increased incidence of neonatal jaundice. However, this may be the result of labor induction rather than a direct effect of the drug. Monitor bilirubin.
    G) Monitor the fetus (ultrasound, fetal heart rate, and tocographic monitoring) following an overdose.
    4.1.2) SERUM/BLOOD
    A) BLOOD/SERUM CHEMISTRY
    1) The use of oxytocin to induce labor has been associated with an increased incidence of neonatal jaundice. However, this may be the result of labor induction rather than a direct effect of the drug (Calder, 1974).
    2) Monitor serum electrolytes, especially sodium, to check for hyponatremia and water intoxication.
    4.1.3) URINE
    A) OTHER
    1) Monitor urine volume and osmolality in patients with hyponatremia.

Treatment

Monitoring

    A) Monitor vital signs and mental status.
    B) Monitor serum electrolytes, especially sodium, to check for hyponatremia and water intoxication.
    C) A CBC, INR, and PTT should be ordered in cases of excessive vaginal bleeding.
    D) Monitor urine volume and osmolality to check for water intoxication.
    E) Obtain an ECG and institute continuous cardiac monitoring following significant exposures.
    F) The use of oxytocin to induce labor has been associated with an increased incidence of neonatal jaundice. However, this may be the result of labor induction rather than a direct effect of the drug. Monitor bilirubin.
    G) Monitor the fetus (ultrasound, fetal heart rate, and tocographic monitoring) following an overdose.

Oral Exposure

    6.5.1) PREVENTION OF ABSORPTION/PREHOSPITAL
    A) Gastrointestinal decontamination is not required as oxytocin is administered intravenously or intramuscularly.
    6.5.2) PREVENTION OF ABSORPTION
    A) Gastrointestinal decontamination is not required as oxytocin is administered intravenously or intramuscularly.
    6.5.3) TREATMENT
    A) SUPPORT
    1) Treatment should include recommendations listed in the PARENTERAL EXPOSURE section when appropriate.

Inhalation Exposure

    6.7.1) DECONTAMINATION
    A) Move patient from the toxic environment to fresh air. Monitor for respiratory distress. If cough or difficulty in breathing develops, evaluate for hypoxia, respiratory tract irritation, bronchitis, or pneumonitis.
    B) OBSERVATION: Carefully observe patients with inhalation exposure for the development of any systemic signs or symptoms and administer symptomatic treatment as necessary.
    C) INITIAL TREATMENT: Administer 100% humidified supplemental oxygen, perform endotracheal intubation and provide assisted ventilation as required. Administer inhaled beta-2 adrenergic agonists, if bronchospasm develops. Consider systemic corticosteroids in patients with significant bronchospasm (National Heart,Lung,and Blood Institute, 2007). Exposed skin and eyes should be flushed with copious amounts of water.

Eye Exposure

    6.8.1) DECONTAMINATION
    A) EYE IRRIGATION, ROUTINE: Remove contact lenses and irrigate exposed eyes with copious amounts of room temperature 0.9% saline or water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist after 15 minutes of irrigation, an ophthalmologic examination should be performed (Peate, 2007; Naradzay & Barish, 2006).

Dermal Exposure

    6.9.1) DECONTAMINATION
    A) DERMAL DECONTAMINATION
    1) DECONTAMINATION: Remove contaminated clothing and wash exposed area thoroughly with soap and water for 10 to 15 minutes. A physician may need to examine the area if irritation or pain persists (Burgess et al, 1999).

Life Support

    A) Support respiratory and cardiovascular function.

Patient Disposition

    6.3.2) DISPOSITION/PARENTERAL EXPOSURE
    6.3.2.1) ADMISSION CRITERIA/PARENTERAL
    A) Patients with significant symptoms and/or abnormal vital signs should be admitted. Pregnant patients with symptoms of vaginal bleeding or contractions should be evaluated by an obstetrician/gynecologist.
    6.3.2.2) HOME CRITERIA/PARENTERAL
    A) There is no data to support home management, and oxytocin is generally only used in the hospital setting.
    6.3.2.3) CONSULT CRITERIA/PARENTERAL
    A) Consult a poison center or medical toxicologist for assistance in managing patients with severe toxicity or in whom the diagnosis is not clear. Obstetrician/gynecologist should be consulted for any case of excessive uterine bleeding or contractions and in the case of inadvertent administration to a pregnant woman.
    6.3.2.5) OBSERVATION CRITERIA/PARENTERAL
    A) Any patient with symptoms should be observed with frequent monitoring of vital signs.

Enhanced Elimination

    A) HEMODIALYSIS
    1) The effectiveness of hemodialysis following oxytocin overdose is unknown. Hemodialysis is probably not required as oxytocin is rapidly removed from plasma through the kidney and the liver.

Abstracts

Case Reports

    A) INFANT
    1) A large, rapid overdose of oxytocin (17,300 milliunits over 20 minutes) during the perinatal period was associated with massive fetal hepatic necrosis and subsequent fetal death. Negative maternal and infant cultures and absence of thrombosis or other identifiable causes of hypoxic-ischemic injury were suggestive of oxytocin-induced, prolonged hepatic ischemia due to swelling of necrotic hepatocytes (Robichaux & Perper, 1992).

Range Of Toxicity

Summary

    A) TOXICITY: Antidiuretic effect of oxytocin can cause water intoxication with seizures, which can occur following large doses (40 to 50 milliunits/min) of oxytocin infused for long periods. A pregnant woman developed severe hypotension and water intoxication after receiving a very large intravenous bolus injection of oxytocin (a bolus of 25 Units of oxytocin instead of a continuous infusion of diluted oxytocin). She recovered after supportive therapy. Five cases of inadvertent epidural administration of oxytocin (0.04 to 5 IU in 4 cases and 10 mL (unknown dose and diluent) in another case) have been reported. Transient hypertension developed in one patient, in the others, no immediate adverse effects were observed.
    B) THERAPEUTIC DOSE: Induction of labor - medically indicated: 0.5 to 1 milliunit/min IV (3 to 6 mL/hr of a 10 units/1000 mL dilute oxytocin solution); gradually increase dose in increments of 1 to 2 milliunits/min every 30 to 60 min. Midtrimester elective abortion: 10 to 20 milliunits/min (20 to 40 drops/min) IV; MAX dose 30 units/12 hr. Postpartum hemorrhage: IV: 10 to 40 units of oxytocin IV infusion (MAX: 40 units to 1000 mL IV solution). IM: 10 units IM given after delivery of the placenta. CHILDREN: Oxytocin is not used in children.

Therapeutic Dose

    7.2.1) ADULT
    A) Oxytocin dosage and rate of infusion are determined by uterine response.
    B) ABORTION
    1) INCOMPLETE, INEVITABLE, OR ELECTIVE ABORTION: 10 units added to 500 mL of a physiologic saline or D5W IV solution after a suction or sharp curettage (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    2) MIDTRIMESTER ELECTIVE ABORTION: 10 to 20 milliunits/min (20 to 40 drops/min) IV; MAX dose 30 units/12 hr (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    C) INDUCTION OF LABOR - MEDICALLY INDICATED
    1) Initial, 0.5 to 1 milliunit/min IV (3 to 6 mL/hr of a 10 units/1000 mL dilute oxytocin solution); gradually increase dose in increments of 1 to 2 milliunits/min every 30 to 60 minutes until desired contraction pattern has been established; once desired frequency of contractions has been reached and labor progressed to 5 to 6 cm dilation, the dose may be reduced by similar increments (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    2) Administration of dosages as high as 64 milliunits/min have been reported (Calder & Embrey, 1975; Coltart & Coe, 1975; Cunningham, 1976; Elder, 1975; Martin, 1978; Schwartz & Jones, 1978; Seidl, 1976; Thiery et al, 1975; AMA, 1986).
    D) POSTPARTUM HEMORRHAGE
    1) INTRAVENOUS: 10 to 40 units of oxytocin IV infusion (MAX: 40 units to 1000 mL IV solution); adjust infusion rate to sustain uterine contractions and control uterine atony (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    2) INTRAMUSCULAR: 10 units IM given after delivery of the placenta (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    7.2.2) PEDIATRIC
    A) Oxytocin is not used in children.

Maximum Tolerated Exposure

    A) Antidiuretic effect of oxytocin can cause water intoxication with seizures, which can occur following large doses (40 to 50 milliunits/min) of oxytocin infused for long periods (Prod Info Pitocin(R) IV, IM injection, 2011).
    B) CASE REPORT: After delivering an infant during cesarean section, a 32-year-old morbidly obese pregnant woman developed severe hypotension (BP 68/34 mm Hg) and water intoxication after receiving an intravenous bolus injection of oxytocin 5 Units of oxytocin, carbetocin 100 mcg, and midazolam 4 mg, followed by another bolus of 25 Units of oxytocin instead of a continuous infusion of diluted oxytocin. She also received 1 L of Hartman's solution and 500 mL of colloid solution. Laboratory analysis revealed plasma sodium of 118 mmol/L and potassium of 3.9 mmol/L, measured just before the end of anesthesia. Initially, she was diagnosed as having an amniotic fluid embolism (AFE), however, she did not show typical clinical manifestations of AFE (eg, coagulopathy, uterine atony, seizures, cardiac arrest, pulmonary edema). At this time, the medication error was identified. Following supportive therapy, including vasopressors, Lasix 20 mg, 0.9% normal saline, and 25% mannitol, she recovered gradually over the next 6 hours (In et al, 2011).
    C) EPIDURAL ADMINISTRATION: A 20-year-old pregnant woman (41 weeks of gestation) who was undergoing cesarean delivery after maximal oxytocin therapy, inadvertently received 5 International Units of oxytocin infused into an epidural catheter. At this time, no fluid could be aspirated from the epidural catheter. Persistent uterine atony was treated with an additional dose of (5 IU) oxytocin administered intravenously. Despite an estimated blood loss of 1200 mL, she remained stable during surgery. On follow-up visits, she had no sequelae from epidural oxytocin administration. Four additional cases of inadvertent oxytocin epidural administration (0.04 to 0.8 IU in 3 cases and 10 mL (unknown dose and diluent) in another case) have been reported. Transient hypertension develop in one patient, in the others no immediate adverse effects were observed (Ross & Wise, 2012).

Toxicity Information

    7.7.1) TOXICITY VALUES
    A) ANIMAL DATA
    1) LD50- (ORAL)MOUSE:
    a) >514 mg/kg (RTECS , 2001)
    2) LD50- (SUBCUTANEOUS)MOUSE:
    a) >514 mg/kg (RTECS , 2001)
    3) LD50- (ORAL)RAT:
    a) >20520 mcg/kg (RTECS , 2001)
    4) LD50- (SUBCUTANEOUS)RAT:
    a) 20520 mcg/kg (RTECS , 2001)

Pharmacology Toxicology

Pharmacologic Mechanism

    A) Oxytocin promotes uterine contractions by increasing intracellular concentrations of calcium in uterine myometrial tissue, thereby increasing the activity of the calcium-dependent phosphorylating enzyme myosin light-chain kinase. The effect is greatest during early labor at term due to the oxytocin receptor concentration which increases during pregnancy and peaks at term. Oxytocin also has pressor and antidiuretic activity which may be exhibited with high doses (Prod Info Pitocin(R) intravenous injection, intramuscular injection, 2014).
    B) PGE & PGF LEVELS
    1) Plasma PGE and PGF levels and plasma PGF metabolite levels rise significantly during oxytocin infusion in women with successful induction of labor when compared to women in which induction failed.
    2) Although oxytocin infusion elicited uterine contractions in all women, the cervix failed to dilate in the women in whom induction failed. Oxytocin may simulate PGF production in the pregnant uterus when it is appropriately sensitized to oxytocin.
    a) This potentiates oxytocin induced contractions which is necessary for the contractions to become efficient in dilating the cervix (Husslein et al, 1981).
    3) The stimulation of PGF production by oxytocin is mediated by oxytocin receptors prevalent in the decidua. Oxytocin has been proposed to provide the stimulus for the accelerated prostaglandin production in the desidua and fetal membranes at the onset of labor (Fuchs et al, 1981).

Physicochemical

Physical Characteristics

    A) white powder (Budavari, 1996)

Molecular Weight

    A) 1007.23

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