Name of the Oxytocic’s Drugs
- Methylergonovine
- Oxytocin
Therapeutic Action
The desired and beneficial actions of oxytocic’s are the following:
- To stimulate uterine contractions like the action of the hypothalamic hormone oxytocin stored in the posterior pituitary.
- They directly affect neuroreceptor sites to stimulate uterine contraction and are especially effective in the gravid uterus.
- Oxytocin, a synthetic form of the hypothalamic hormone, also stimulates the lacteal glands in the breast to contract, promoting milk ejection in lactating women.
| METHYLERGONOVINE |
| Availability: Injection: 0.2 mg/ml; Tablets: 0.2 mg |
| Administration And Handling: IV Administration. Give IV only in emergency because of potential for HTN & CVA Give over >1 min & monitor BP & uterine contractions. Be aware that drug isn’t routinely given I.V. because of risk of severe hypertension and cerebrovascular accident (CVA). Monitor blood pressure and uterine contractions during Administration. If I.V. use is necessary, give dose over 1 minute. Dose may be diluted in 5 ml of 0.9% sodium chloride Injection. Be aware that prolonged therapy should be avoided because of ergotism risk. Storage: Refrigerate ampules |
| Prevention and treatment of postpartum haemorrhage: Adults: 0.2 mg I.M.; repeat q 2 to 4 hours as needed to a total of five doses. In emergencies, 0.2 mg I.V. over 1 minute. After initial I.M. or I.V. dose, 0.2 mg P.O. q 6 to 8 hours for 2 to 7 days; decrease dosage if cramping occurs |
| Refractory Cluster Headache (Off-label): 0.2 mg PO q6-8hr, not to exceed 6 months |
Mechanism of Action:
Directly stimulates vascular smooth muscle contractions in uterus and cervix and decreases bleeding after delivery
Indications:
- Management of uterine atony
- Haemorrhage and subinvolution of uterus following delivery of placenta.
- Control uterine haemorrhage following delivery of anterior shoulder in second stage of labor.
Contraindications and Cautions:
- Hypersensitivity to drug
- Hypertension
- Toxemia
- Pregnancy (except during third stage of labor)
Use cautiously in:
- Severe hepatic or renal disease, vascular disease, jaundice, sepsis
- Patients in second stage of labor.
Metabolism and Half- Life:
Rapidly absorbed from GI tract after IM administration. Distributed rapidly to plasma, extracellular fluid, tissues.
Metabolized in liver. Primarily excreted in urine. Half-life: 0.5–2 hrs.
Drug Interactions:
- May increase hypertensive effect of Dopamine, norepinephrine, phenylephrine, vasopressin.
- Strong CYP3A4 inhibitors (e.g., clarithromycin, ketoconazole, ritonavir) may increase concentration/effect.
- Beta blockers (e.g., carvedilol, labetalol, metoprolol) may increase vasoconstrictive effect of ergot derivatives.
- May decrease vasodilation effect of nitroglycerine.
- May increase vasoconstricting effect of serotonin 5-HT1D receptor agonists (e.g., Sumatriptan).
- May decrease serum prolactin.
Side effects
- Frequent: Nausea, uterine cramping, vomiting.
- Occasional: Abdominal pain, diarrhea, dizziness, diaphoresis, tinnitus, bradycardia, chest pain.
- Rare: Allergic reaction (rash, pruritus), dyspnea, severe or sudden hypertension
Nursing Considerations
Baseline assessment
- Determine baseline serum calcium level, B/P, pulse.
- Assess for any evidence of bleeding before administration.
Intervention/evaluation
- Monitor uterine tone, bleeding, B/P, pulse q15min until stable (about 1–2 hrs).
- Assess extremities for color, warmth, movement, pain. Report chest pain promptly.
- Provide support with ambulation if dizziness occurs.
- Know that if used during third stage of labor, drug increases risk of hemorrhage and infection.
- When giving I.V., closely monitor blood pressure, pulse, uterine contractions, and bleeding.
- Monitor patient for adverse effects.
Patient/family teaching
- Avoid smoking causes increased vasoconstriction.
- Report increased cramping, bleeding, foul-smelling lochia.
- Report pale, cold hands/feet (possibility of diminished circulation).
- Inform patient and family of reason for using drug and provide reassurance.
- Tell patient drug may cause nausea, vomiting, dizziness, increased blood pressure, headache, ringing in ears, chest pain, or shortness of breath.
- Advise her to report severe or troublesome symptoms
| OXYTOCIN |
| Availability: Injection: (Pitocin): 10 units/mL. Injection Solution: 30 units/500 mL. |
| Administration/handling: IV Reconstitution • Dilute 10–40 units (1–4 mL) in 1,000 mL of 0.9% NaCl, lactated Ringer’s, or D5W to provide concentration of 10–40 milliunits/mL solution. Rate of administration: Give by IV infusion (use infusion device to carefully control rate of flow as ordered by physician). Don’t give by I.V. bolus injection. Infuse I.V. using controlled-infusion device. Be aware that drug isn’t routinely given I.M. Know that drug should be given only to inpatients at critical care facilities when prescriber is immediately available. Storage: Store at room temperature |
| Induction or Stimulation of Labor: IV: ADULTS: 0.5–1 milliunit/min. May gradually increase in increments of 1–2 milliunits/min q30–60 minutes until desired contraction pattern is established. Rates greater than 9–10 milliunits/min are rarely required. |
| Abortion: IV: ADULTS: (Midterm elective abortion): 10–20 milliunits/min. Maximum: 30 units/12-hr dose. (Incomplete, inevitable, or elective abortion): 10 units as IV infusion after suction or a sharp curettage. |
| Control of Postpartum Bleeding: IV infusion: ADULTS: 5–10 units may be given initially and can be followed by a maintenance infusion of 10–40 units in 1,000 mL IV fluid at rate sufficient to sustain uterine contractions and control uterine atony. IM: ADULTS: 10 units (total dose) after delivery. |
Mechanism of Action:
Activates receptors that trigger increase in intracellular calcium levels in uterine myofibrils; increases prostaglandin production.
Therapeutic Effect: Stimulates uterine contractions
Indications:
Antepartum:
- Induction of labor in pts with medical indication (e.G., At or near term)
- To stimulate reinforcement of labor
- As adjunct in managing incomplete or inevitable abortion.
Postpartum:
- To produce uterine contractions during third stage of labor
- To control postpartum bleeding/hemorrhage.
Off-label uses
- Antepartum fetal heart rate testing
- Breast enlargement
Contraindications and Cautions:
- Hypersensitivity to oxytocin.
- Adequate uterine activity that fails to progress
- Cephalopelvic disproportion,
- Fetal distress without imminent delivery
- Grand multiparity
- Hyperactive or hypertonic uterus
- Obstetric emergencies that favour surgical intervention
- Prematurity
- Unengaged fetal head
- Unfavourable fetal position/presentation
- When vaginal delivery is contraindicated (e.g., active genital herpes infection, invasive cervical cancer, placenta previa, cord presentation).
Cautions:
- Induction of labor should be for medical, not elective, reasons.
- Generally, not recommended in fetal distress, hydramnios, partial placental previa, predisposition to uterine rupture.
Metabolism and Half- Life:
- Rapidly absorbed through nasal mucous membranes.
- Protein binding: 30%. Distributed in extracellular fluid.
- Metabolized in liver, kidney.
- Primarily excreted in urine. Half-life: 1–6 min.
Drug Interactions:
- Dinoprostone, misoprostol may increase adverse effects.
- Sympathomimetics: postpartal hypertension
- Thiopental anesthetics: delayed anesthesia induction
- Vasoconstrictors: severe hypertension (when given within 3 to 4 hours of oxytocin)
Side Effects:
- Occasional: Tachycardia, premature ventricular contractions, hypotension, nausea, vomiting.
- Rare: Nasal: Lacrimation/tearing, nasal irritation, rhinorrhea, unexpected uterine bleeding/ contractions.
- Hypertonicity may occur with tearing of uterus, increased bleeding, abruptio placentae (i.e., placental abruption),
- cervical/vaginal lacerations.
- Fetal: Bradycardia, CNS/brain damage, trauma due to rapid propulsion, low Apgar score at 5 min, retinal hemorrhage occur rarely. Prolonged IV infusion of oxytocin with excessive fluid volume has caused severe water intoxication with seizures, coma, death.
Nursing Considerations
Baseline assessment
- Assess baselines for vital signs, B/P, fetal heart rate.
- Determine frequency, duration, strength of contractions.
Intervention/evaluation
- Monitor B/P, pulse, respirations, fetal heart rate, intrauterine pressure, contractions (duration, strength, frequency) q15min.
- Notify physician of contractions that last longer than 1 min, occur more frequently than every 2 min, or stop.
- Maintain careful I&O; be alert to potential water intoxication. .
- Continuously monitor contractions, fetal and maternal heart rate, and maternal blood pressure and ECG.
- Discontinue infusion if uterine hyperactivity occurs.
- Monitor patient extremely closely during first and second stages of labor because of risk of cervical laceration, uterine rupture, and maternal and fetal death.
- When giving drug to control postpartal bleeding, monitor and record vaginal bleeding.
Patient/family teaching
- Inform patient about risks and benefits of oxytocin-induced labor.
- Teach patient to recognize and immediately report adverse drug effects.
- Keep pt, family informed of labor progress.
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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