Usage
Methylergometrine is prescribed for the prevention and control of postpartum hemorrhage (excessive bleeding after childbirth) caused by uterine atony (failure of the uterus to contract adequately). It belongs to the pharmacological classification of ergot alkaloids and is categorized as an oxytocic or uterotonic agent.
Methylergometrine works by stimulating smooth muscle contraction in the uterus. This increases the tone, rate, and strength of uterine contractions, helping to constrict blood vessels and reduce bleeding.
Alternate Names
Methylergometrine is also known as methylergonovine. A common brand name is Methergine.
How It Works
Pharmacodynamics: Methylergometrine directly stimulates uterine smooth muscle, leading to strong, sustained contractions. It also exhibits some vasoconstrictive properties on peripheral blood vessels.
Pharmacokinetics:
- Absorption: Methylergometrine is rapidly absorbed following intramuscular (IM) or intravenous (IV) administration, and well-absorbed orally.
- Metabolism: Primarily metabolized in the liver.
- Elimination: Excreted mainly through the biliary system (feces) with some renal excretion. The elimination half-life is approximately 2-3 hours.
Mode of Action: Methylergometrine acts as a partial agonist at alpha-adrenergic, dopaminergic, and serotonergic receptors. Its primary effect on uterine smooth muscle is attributed to its action on serotonin (5-HT2) receptors, causing strong, sustained contractions.
Elimination Pathways: Primarily hepatic metabolism and biliary excretion, with some renal excretion.
Dosage
Standard Dosage
Adults:
- Oral: 0.2 mg every 6-8 hours for up to 1 week postpartum.
- IM: 0.2 mg after delivery of the anterior shoulder, placenta, or during the postpartum period. May be repeated every 2-4 hours as needed, not to exceed 5 doses.
- IV: 0.2 mg administered slowly over at least 60 seconds, only in emergencies due to risk of hypertension and stroke.
Children: Use and dose must be determined by a doctor. Pediatric safety and efficacy haven’t been firmly established.
Special Cases:
- Elderly Patients: Use with caution due to potential age-related decline in organ function. Dose adjustment may be necessary.
- Patients with Renal Impairment: Use with caution. Dose reduction may be needed.
- Patients with Hepatic Dysfunction: Use with caution. Dose reduction may be needed.
- Patients with Comorbid Conditions: Use with caution in patients with hypertension, coronary artery disease, peripheral vascular disease, sepsis, and pre-eclampsia.
Clinical Use Cases
Methylergometrine’s primary clinical use is for the prevention and treatment of postpartum hemorrhage due to uterine atony. It’s not generally indicated for intubation, surgical procedures, mechanical ventilation, or ICU use outside the context of postpartum care. In emergency situations of postpartum hemorrhage unresponsive to other measures, IV administration may be life-saving.
Dosage Adjustments
Dose adjustments are required based on patient-specific factors such as renal or hepatic impairment, comorbid conditions, and other medications.
Side Effects
Common Side Effects
Nausea, vomiting, headache, dizziness, abdominal pain, diarrhea, increased sweating, unpleasant taste in mouth, tinnitus (ringing in ears), stuffy nose.
Rare but Serious Side Effects
Hypertension, stroke, seizures, myocardial infarction, coronary artery spasm, shortness of breath, chest pain, allergic reactions (rash, itching, hives, swelling), peripheral vasoconstriction (cold hands/feet, pain/redness/swelling of limbs).
Long-Term Effects
Ergotism (with prolonged use), pleural fibrosis, retroperitoneal fibrosis.
Adverse Drug Reactions (ADR)
Severe hypertension, stroke, myocardial infarction, seizures, anaphylaxis.
Contraindications
Hypersensitivity to methylergometrine or other ergot alkaloids; pregnancy; pre-eclampsia or eclampsia; hypertension; severe hepatic or renal impairment; sepsis; coronary artery disease; peripheral vascular disease.
Drug Interactions
Methylergometrine interacts with numerous medications, including:
- CYP3A4 Inhibitors: (e.g., azole antifungals, macrolide antibiotics, HIV protease inhibitors) increase methylergometrine levels.
- Vasoconstrictors: (e.g., other ergot alkaloids, sympathomimetics, triptans) enhance vasoconstricting effects and increase hypertension risk.
- Other Uterotonics: (e.g., oxytocin, prostaglandins) additive effects can increase risk of uterine rupture.
- Beta-blockers: may enhance vasoconstriction.
Interactions also exist with certain antidepressants, antifungals, antihypertensives, and medications for migraine headaches. Alcohol, smoking, and grapefruit juice may affect drug metabolism.
Pregnancy and Breastfeeding
Pregnancy Safety Category: C (IM/IV/Oral). Contraindicated during pregnancy. Use only after delivery of the baby.
Fetal Risks: Uterine contractions can lead to fetal distress or demise if administered during pregnancy.
Breastfeeding: Avoid breastfeeding for at least 12 hours after the last dose. Drug is excreted in breast milk and may cause adverse effects in infants.
Drug Profile Summary
- Mechanism of Action: Stimulates uterine contraction and vasoconstriction.
- Side Effects: Nausea, vomiting, headache, hypertension, stroke (rare).
- Contraindications: Pregnancy, hypertension, pre-eclampsia.
- Drug Interactions: CYP3A4 inhibitors, vasoconstrictors, other uterotonics.
- Pregnancy & Breastfeeding: Contraindicated in pregnancy. Avoid breastfeeding for 12 hours post-dose.
- Dosage: 0.2 mg IM/IV/oral; dosage varies postpartum.
- Monitoring Parameters: Blood pressure, heart rate, uterine response, vaginal bleeding.
Popular Combinations
Methylergometrine is sometimes used in combination with oxytocin for postpartum hemorrhage but this practice is not recommended as it can increase the risk of hypertension.
Precautions
- General Precautions: Monitor blood pressure and uterine response closely. Screen for pre-existing medical conditions.
- Specific Populations: Contraindicated in pregnancy. Avoid breastfeeding for 12 hours post-dose. Use cautiously in the elderly and those with renal/hepatic impairment.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Methylergometrine?
A: 0.2 mg IM/IV after delivery or 0.2 mg orally 3-4 times/day for up to one week postpartum. Adjust dose based on patient-specific factors.
Q2: How does Methylergometrine work?
A: It stimulates uterine smooth muscle contraction and vasoconstriction, reducing postpartum bleeding.
Q3: When is Methylergometrine contraindicated?
A: During pregnancy, in patients with hypertension, pre-eclampsia, or hypersensitivity to ergot alkaloids.
Q4: What are the common side effects of Methylergometrine?
A: Nausea, vomiting, headache, dizziness, abdominal pain.
Q5: What are the serious side effects of Methylergometrine?
A: Hypertension, stroke, seizures, myocardial infarction.
Q6: What are the drug interactions of Methylergometrine?
A: CYP3A4 inhibitors, vasoconstrictors, other uterotonics.
Q7: Can Methylergometrine be used during breastfeeding?
A: Breastfeeding should be avoided for at least 12 hours following the last dose.
Q8: How should Methylergometrine be administered?
A: Orally, IM, or IV (in emergencies only, administer slowly).
Q9: What is the mechanism of action of Methylergometrine?
A: Acts as a partial agonist at alpha-adrenergic, dopaminergic, and serotonergic receptors, primarily stimulating 5-HT2 receptors in the uterus.
