Pharmacology · Class
Ergot alkaloids !
Drugs derived from the ergot fungus that cause strong, sustained contraction of the uterus and of blood vessels; used for bleeding after birth and for migraine.
Updated 2026-11-01
What they are
Ergoline derivatives that act on serotonin and alpha-adrenergic receptors. Methylergometrine and ergometrine contract the uterus and treat postpartum haemorrhage; ergotamine narrows cranial vessels and treats migraine attacks.
Mechanism of action
They are partial agonists or antagonists at serotonin (5-HT) and alpha-adrenergic receptors. On the uterus they cause a sustained contraction that controls bleeding; on blood vessels they cause vasoconstriction, which explains hypertension, coronary spasm and ischaemia of the limbs. They are metabolised by CYP3A4.
Target: Serotonin (5-HT) and alpha-adrenergic receptors
Drugs in this class
- MethylergometrineErgot derivative that causes a strong, sustained contraction of the uterus after the placenta is delivered. It raises…Serotonin 5-HT2 and alpha-adrenergic receptors of the myometrium
- ErgometrineErgot alkaloid on the WHO essential list that contracts the uterus to control bleeding after birth. Like…Serotonin 5-HT2 and alpha-adrenergic receptors of the myometrium
- ErgotamineErgot alkaloid that narrows cranial blood vessels to stop migraine attacks. Dangerous with CYP3A4 inhibitors and…Serotonin 5-HT1B/1D receptors (and alpha-adrenergic receptors)
Others in the class
- Dihydroergotamine
- Methysergide
Test yourself
Think of the answer, then tap the question to see it.
Why are ergot alkaloids avoided in pre-eclampsia?
They constrict blood vessels and can cause sudden hypertension, seizures and stroke.
Which group of antibiotics should not be combined with ergot alkaloids, and why?
Macrolides such as clarithromycin or erythromycin: they inhibit CYP3A4, ergot levels rise and severe ischaemia (ergotism) can occur.
Which ergot alkaloid is used for migraine rather than for bleeding after birth?
Ergotamine.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - METHYLERGONOVINE MALEATE injection, solution (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - ERGOTAMINE TARTRATE AND CAFFEINE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.