Methylergonovine (Methergine)
Methergine
Ergot alkaloid uterotonic (semi-synthetic)
Direct uterine smooth muscle stimulant — potent + sustained contraction. Also vasoconstrictor (especially coronary + cerebral arteries) → CONTRAINDICATED in HTN, preeclampsia, CAD.
Indications
- •Postpartum hemorrhage from uterine atony — second-line after oxytocin
- •Subinvolution of uterus postpartum
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Postpartum hemorrhage | 0.2 mg IM q2-4 h max (slow IV 0.2 mg over 1 min — generally avoided due to severe HTN) | — |
Pharmacokinetics
Onset IM 2-7 min, IV 1-5 min. Duration ~3 h. Hepatic metabolism.
Hemodynamic effects
↑BP (significant — vasoconstriction). Coronary spasm + cerebral vasoconstriction reported. Avoid IV if alternatives available.
Side effects
- !Severe HYPERTENSION (especially with rapid IV)
- !Coronary vasospasm + MI
- !Cerebral vasoconstriction + stroke (with IV bolus)
- !Nausea + vomiting
- !Headache
Contraindications
- ×HYPERTENSION (any) — absolute
- ×Preeclampsia/eclampsia
- ×Coronary artery disease
- ×Peripheral vascular disease
- ×Concurrent CYP3A4 inhibitors (severe vasospasm reported)
Clinical pearls
- ★PPH stepwise: oxytocin → METHYLERGONOVINE → carboprost → misoprostol → mechanical/surgical.
- ★HYPERTENSION + PREECLAMPSIA — major contraindication. Skip to carboprost or misoprostol.
- ★Give IM, NOT IV (severe HTN with IV bolus). IV reserved for life-threatening hemorrhage when other agents unavailable.
- ★Prepare antihypertensive (labetalol, nicardipine) ready when given.
- ★Avoid in patients with HIV protease inhibitors, azole antifungals, macrolides (CYP3A4 inhibitors → severe vasospasm).
Other drugs in OB / GYN Related
- Oxytocin
Stimulates uterine smooth muscle contraction (uterine OXTR receptors). ADH-like action at high doses.
- Carboprost (Hemabate)
15-methylated synthetic analog of prostaglandin F2α. Binds prostaglandin F receptors on uterine smooth muscle → potent contraction. Also constricts pulmonary smooth muscle → BRONCHOSPASM (contraindication in asthma).
- Misoprostol (Cytotec)
Synthetic PGE1 analog. Binds prostaglandin E receptors on uterine smooth muscle → contraction. Also: cytoprotective gastric mucosa (original indication for NSAID-induced ulcers); cervical ripening; GI motility.
- Terbutaline
β2 agonism → uterine + bronchial smooth-muscle relaxation.
Browse all classes: /reference/drugs
Suggested reading
- •Miller's Anesthesia, 9e
- •FDA package insert
