methylergonovine

[meth″il-er″go-no´vin] an oxytocic used as the maleate salt especially to prevent or combat postpartum hemorrhage or atony.

methylergonovine

(meth-ill-er-goe-noe-veen) methylergonovine,

Methergine

(trade name)

Classification

Therapeutic: oxytocic
Pharmacologic: ergot alkaloids
Pregnancy Category: C

Indications

Prevention and treatment of postpartum or postabortion hemorrhage caused by uterine atony or subinvolution.

Action

Directly stimulates uterine and vascular smooth muscle.

Therapeutic effects

Uterine contraction.

Pharmacokinetics

Absorption: Well absorbed following oral or IM administration.Distribution: Unknown. Enters breast milk in small quantities.Metabolism and Excretion: Probably metabolized by the liver.Half-life: 30–120 min.

Time/action profile (effects on uterine contractions)

ROUTE	ONSET	PEAK	DURATION
PO	5–15 min	unknown	3 hr
IM	2–5 min	unknown	3 hr
IV	immediate	unknown	45 min–3 hr

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Obstetric: Should not be used to induce labor; Lactation: Do not breast feed during treatment and for 12 hours after the last doseConcurrent use of potent CYP3A4 inhibitorsUse Cautiously in: Hypertensive or eclamptic patients (more susceptible to hypertensive and arrhythmogenic side effects);History of or risk factors for coronary artery diseaseSevere hepatic or renal disease;Sepsis.Concurrent use of moderate CYP3A4 inhibitorsExercise Extreme Caution in: Obstetric: Third stage of labor.

Adverse Reactions/Side Effects

Central nervous system

stroke (life-threatening)
dizziness
headache

Ear, Eye, Nose, Throat

tinnitus

Respiratory

dyspnea

Cardiovascular

hypertension (life-threatening)
arrhythmias
AV block
chest pain
palpitations

Gastrointestinal

nausea (most frequent)
vomiting (most frequent)

Genitourinary

cramps (most frequent)

Dermatologic

diaphoresis

Neurologic

paresthesia

Miscellaneous

allergic reactions

Interactions

Drug-Drug interaction

Excessive vasoconstriction may result when used with heavy cigarette smoking (nicotine ), other vasopressors, such as dopamine, or beta-blockers.Potent CYP3A4 inhibitors, including erythromycin, clarithromycin, troleandomycin, ritonavir, indinavir, nelfinavir, delavirdine, ketoconazole, itraconazole, or voriconazole may ↑ levels and ↑ risk of ischemia; concurrent use contraindicatedModerate CYP3A4 inhibitors including saquinavir, nefazodone, fluconazole, fluoxetine, fluvoxamine, zileuton, or clotrimazole may ↑ levels; use with cautionCYP3A4 inducers including nevirapine and rifampin may ↓ levelsAnesthetics may ↓ its oxytocic propertiesMay ↓ the antianginal effects of nitrates Grapefruit juice may ↑ levels; use with caution

Route/Dosage

Oral (Adults) 200–400 mcg (0.2–0.4 mg) q 6–12 hr for 2–7 days.Intramuscular Intravenous (Adults) 200 mcg (0.2 mg) q 2–4 hr for up to 5 doses.

Availability (generic available)

Tablets: 200 mcg (0.2 mg) Injection: 200 mcg (0.2 mg)/mL

Nursing implications

Nursing assessment

Monitor BP, heart rate, and uterine response frequently during medication administration. Notify health care professional promptly if uterine relaxation becomes prolonged or if character of vaginal bleeding changes.
Assess for signs of ergotism (cold, numb fingers and toes, chest pain, nausea, vomiting, headache, muscle pain, weakness).
Lab Test Considerations: If no response to methylergonovine, calcium levels may need to be assessed. Effectiveness of medication is ↓ with hypocalcemia.
- May cause ↓ serum prolactin levels.

Potential Nursing Diagnoses

Acute pain (Side Effects)

Implementation

Intravenous Administration
Intravenous: IV administration is used for emergencies only. Oral and IM routes are preferred.
Diluent: May be given undiluted or diluted in 5 mL of 0.9% NaCl and administered through Y site. Do not add to IV solutions. Do not mix in syringe with any other drug. Refrigerate; stable for storage at room temperature for 60 days; deteriorates with age. Use only solution that is clear and colorless and that contains no precipitate.Concentration: 0.2 mg/mL.
Rate: Administer at a rate of 0.2 mg over at least 1 min.
Y-Site Compatibility: heparin, hydrocortisone sodium succinate, potassium chloride, vitamin B complex with C

Patient/Family Teaching

Instruct patient to take medication as directed; do not skip or double up on missed doses. If a dose is missed, omit it and return to regular dose schedule.
Advise patient that medication may cause menstrual-like cramps.
Caution patient to avoid smoking, because nicotine constricts blood vessels.
Instruct patient to notify health care professional if infection develops, as this may cause increased sensitivity to the medication.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.

Evaluation/Desired Outcomes

Contractions that maintain uterine tone and prevent postpartum hemorrhage.

methylergonovine