Ergot

Metadata

Regulatory Status

United States

• FDA-approved drugs derived from ergot alkaloids:
  • Ergotamine tartrate (with caffeine as Cafergot) — acute migraine treatment
  • Dihydroergotamine mesylate (D.H.E. 45 injection, Migranal nasal spray, Trudhesa nasal spray) — acute migraine and cluster headache
  • Methylergonovine maleate (Methergine) — postpartum hemorrhage
  • Bromocriptine mesylate (Parlodel) — Parkinson’s disease, hyperprolactinemia, acromegaly, type 2 diabetes (Cycloset)
  • Cabergoline (Dostinex) — hyperprolactinemia
• Crude ergot: Not approved as a drug or dietary supplement. Not GRAS.
• LSD (lysergic acid diethylamide): Schedule I controlled substance; derived from lysergic acid, a natural ergot alkaloid.

European Union

• EMA-authorized products: Ergotamine, DHE, methylergonovine, bromocriptine, and cabergoline have marketing authorizations in EU member states. Methysergide was formerly marketed for migraine prophylaxis but has been withdrawn in most countries.
• Nicergoline: Marketed in several EU countries for cognitive impairment in elderly patients.
• European Pharmacopoeia: Contains monographs for ergotamine tartrate, dihydroergotamine mesylate, and ergometrine maleate.

World Health Organization

• Essential Medicines List: Ergometrine (ergonovine) injection is on the WHO Model List of Essential Medicines for the management of postpartum hemorrhage, reflecting its critical role in maternal health in resource-limited settings.

Historical

• Pharmacopoeial inclusion: Ergot (as crude drug) was included in the United States Pharmacopeia from 1820 to 1942, primarily for its oxytocic properties in obstetrics. It was replaced by purified ergot alkaloids as analytical techniques improved.
• British Pharmacopoeia: Ergot was listed for obstetric and vascular indications until replaced by purified derivatives.

Conditions & Indications

Primary: Acute Migraine and Cluster Headache

• Ergotamine: Used for acute migraine since the 1920s. Mechanism involves agonism at 5-HT1B/1D receptors on cranial blood vessels, causing vasoconstriction of dilated meningeal and temporal arteries. Administered as sublingual tablets (2 mg initially, then 2 mg every 30 minutes, maximum 6 mg/attack, 10 mg/week) or rectal suppositories (combined with caffeine).
• Dihydroergotamine (DHE): Semi-synthetic derivative with improved pharmacological profile: greater alpha-adrenergic antagonist activity, less arterial vasoconstriction, less nausea, and faster onset than ergotamine. Available as injection (1 mg IM/IV/SC), nasal spray (0.5 mg per nostril), and most recently Trudhesa (DHE nasal spray with enhanced bioavailability). Remains a treatment option for patients who fail triptans.
• Clinical positioning: Ergot alkaloids have been largely supplanted by triptans (sumatriptan, etc.) for first-line acute migraine therapy due to better tolerability, but DHE retains a role for refractory migraine, status migrainosus, and medication-overuse headache detoxification.

Primary: Postpartum Hemorrhage

• Ergometrine (ergonovine): Powerful uterotonic that stimulates sustained tonic contraction of uterine smooth muscle, reducing postpartum hemorrhage by mechanically compressing uterine blood vessels. WHO essential medicine. Administered IM or IV (0.2 mg). Also used as methylergonovine (Methergine).
• Clinical significance: Particularly important in resource-limited settings where oxytocin may not be available or cold chain cannot be maintained (though ergometrine also has temperature stability limitations).

Secondary: Hyperprolactinemia and Prolactinoma

• Bromocriptine: Ergot-derived dopamine D2 receptor agonist. First-line medical therapy for prolactin-secreting pituitary adenomas. Normalizes prolactin levels in approximately 80% of patients and reduces tumor size in 60—70%.
• Cabergoline: Longer-acting ergot-derived D2 agonist with superior efficacy and tolerability compared to bromocriptine. Preferred agent for prolactinoma in current guidelines.

Secondary: Parkinson’s Disease

• Bromocriptine: Historically used as adjunctive therapy for Parkinson’s disease. Largely replaced by non-ergot dopamine agonists (pramipexole, ropinirole) due to risk of fibrotic complications (retroperitoneal, cardiac valvular, and pulmonary fibrosis).
• Pergolide: Ergot-derived D1/D2 agonist withdrawn in many markets due to cardiac valvular fibrosis risk.
• Cabergoline: Used in some markets for Parkinson’s disease with careful cardiac monitoring.

Emerging/Preclinical

• Cognitive enhancement in elderly (nicergoline): Marketed in some European countries for age-related cognitive decline, based on vasodilatory and metabolic effects. Evidence quality is moderate. [CONTESTED]
• Type 2 diabetes (bromocriptine): Cycloset (bromocriptine quick-release) was FDA-approved in 2009 for type 2 diabetes, based on a hypothesized mechanism involving dopaminergic resetting of hypothalamic metabolic circuitry. Use remains limited.

Mechanism of Action

Primary Mechanisms

1. Serotonin receptor agonism (5-HT1B/1D): Ergotamine and DHE are potent agonists at serotonin 5-HT1B and 5-HT1D receptors. 5-HT1B receptors are located on cranial blood vessel smooth muscle and mediate vasoconstriction. 5-HT1D receptors are located on trigeminal nerve terminals and inhibit release of vasoactive neuropeptides (CGRP, substance P). This dual mechanism — vascular constriction and neurogenic inflammation inhibition — underlies the antimigraine effects. Ergot alkaloids were described as “dirty drugs” by pharmacologists because they interact with multiple receptor systems simultaneously.

2. Alpha-adrenergic agonism: Ergotamine and DHE stimulate alpha-1 and alpha-2 adrenergic receptors, producing vasoconstriction in both arterial and venous vascular beds. DHE has greater venoconstrictive than arterial constrictive activity compared to ergotamine, which may contribute to its antimigraine efficacy (by reducing venous pooling and intracranial compliance) while producing less peripheral arterial vasospasm.

3. Dopamine D2 receptor agonism: Bromocriptine, cabergoline, and pergolide are potent D2 receptor agonists. This mechanism underlies their use in:

   • Hyperprolactinemia (D2 activation on lactotroph cells inhibits prolactin synthesis and secretion)
   • Parkinson’s disease (D2 activation in the nigrostriatal pathway compensates for dopaminergic neuronal loss)
   • Type 2 diabetes (hypothalamic dopaminergic mechanism)

4. Uterotonic/oxytocic action: Ergometrine (ergonovine) and methylergonovine produce powerful sustained tonic contraction of uterine smooth muscle through combined alpha-adrenergic agonism and serotonergic mechanisms. This contraction compresses uterine blood vessels, reducing postpartum hemorrhage. The uterotonic effect is most potent on the gravid uterus and early postpartum uterus.

Secondary Mechanisms

• 5-HT2A/2B/2C agonism: Ergot alkaloids variably activate 5-HT2 receptor subtypes. 5-HT2B agonism is particularly significant as it mediates the fibrotic complications (cardiac valvular fibrosis, retroperitoneal fibrosis) associated with chronic use of pergolide, cabergoline, and methysergide.
• Dopamine D1 receptor activity: Some ergot derivatives (pergolide) have D1 agonist activity contributing to their anti-parkinsonian effects.
• Lysergic acid and LSD: Albert Hofmann at Sandoz Laboratories synthesized LSD-25 (lysergic acid diethylamide) from lysergic acid in 1938 and discovered its psychoactive properties in 1943. LSD is a potent 5-HT2A agonist producing profound alterations in perception, cognition, and consciousness. While not a therapeutic product of ergot, this derivation represents one of the most historically significant pharmaceutical discoveries arising from a fungal natural product.

Clinical Evidence Summary

Established Pharmaceutical Applications

Historical Epidemiology of Ergotism

Evidence Limitations

• Crude ergot: No modern clinical trials with crude ergot preparations (sclerotium). All current clinical evidence relates to purified or semi-synthetic derivatives. The crude fungal product has an extremely narrow therapeutic index and unpredictable alkaloid composition.
• Ergotamine declining use: Ergotamine use has declined substantially since the introduction of triptans in the 1990s. Most recent clinical data for ergotamine dates from the 1990s or earlier. Current guidelines position ergotamine as a second- or third-line option.
• Fibrotic complications: Long-term use of ergot-derived dopamine agonists (pergolide, cabergoline at Parkinson’s disease doses, methysergide) is associated with fibrotic complications mediated by 5-HT2B receptor agonism. This has led to withdrawal of pergolide and methysergide from many markets and mandates echocardiographic monitoring for cabergoline at higher doses.

Safety Profile

General Assessment

Ergot alkaloids have a narrow therapeutic index and complex, multi-receptor pharmacology that necessitates careful clinical use. Crude ergot consumption is dangerous and historically caused devastating epidemics. Modern pharmaceutical use of purified ergot derivatives is well-established but requires attention to contraindications, dosing limits, and drug interactions. The safety profile varies substantially between different ergot derivatives.

Contraindications

• Pregnancy: Absolutely contraindicated. Ergot alkaloids cause powerful uterine contraction and vasospasm. Historical use as abortifacients. Teratogenic in animal studies.
• Vascular disease: Coronary artery disease, peripheral vascular disease (including Raynaud’s), cerebrovascular disease. Risk of vasospasm, ischemia, gangrene.
• Uncontrolled hypertension: Vasoconstriction can worsen hypertension and precipitate hypertensive crisis.
• Hepatic/renal impairment: Impaired metabolism increases ergot alkaloid exposure and toxicity risk.
• Sepsis: Impaired vascular regulation increases risk of severe vasospasm.
• Concurrent triptan use: Combined vasoconstriction risk. Minimum 24-hour separation required.
• CYP3A4 inhibitors: Ergotamine and DHE are CYP3A4 substrates. Strong inhibitors (ketoconazole, itraconazole, erythromycin, clarithromycin, HIV protease inhibitors) dramatically increase ergot alkaloid levels, risking ergotism.

Drug Interactions

• Triptans: Additive vasospasm. Do not use within 24 hours of each other.
• CYP3A4 inhibitors: Macrolide antibiotics, azole antifungals, HIV protease inhibitors — contraindicated combinations. Cases of acute ergotism (limb ischemia, gangrene) reported.
• Beta-blockers: Additive peripheral vasoconstriction.
• Other vasoconstrictors: Additive vasospasm risk.
• Dopamine agonists/antagonists: Complex interactions due to dopaminergic activity of some ergot derivatives.

Side Effects

• Ergotamine/DHE (acute use): Nausea (most common, 10—20%), vomiting, leg cramps, numbness/tingling in extremities, chest tightness, rebound headache with overuse (>10 days/month). Rectal and nasal formulations have lower rates of nausea.
• Bromocriptine: Nausea, orthostatic hypotension, dizziness, headache, fatigue.
• Cabergoline: Nausea, headache, dizziness. At high doses (Parkinson’s disease): cardiac valvular fibrosis risk requiring echocardiographic monitoring.

Toxicology — Ergotism

• Convulsive ergotism: Characterized by painful muscle spasms and convulsions, hallucinations, crawling skin sensations, and psychosis. Caused primarily by lysergic acid amide derivatives.
• Gangrenous ergotism: Characterized by intense burning pain in extremities (“St. Anthony’s fire”), followed by progressive ischemia and dry gangrene of fingers, toes, and limbs. Caused by sustained vasoconstriction from ergotamine-type alkaloids. Can result in limb loss.
• Modern iatrogenic ergotism: Rare but still reported, typically from drug interactions (CYP3A4 inhibitors) or overdose. Presents as acute limb ischemia requiring emergency treatment (vasodilators, heparin, sometimes surgical intervention).
• Medication-overuse headache: Ergotamine can rapidly induce medication-overuse headache even at recommended doses if used more than 10 days per month.

Clinical Dosage

Ergotamine Tartrate (Acute Migraine)

• Sublingual: 2 mg at onset, then 2 mg every 30 minutes. Maximum 6 mg per attack, 10 mg per week.
• Rectal (with caffeine): 2 mg suppository at onset. Maximum 2 suppositories per attack.
• Duration limit: Not to exceed 10 days per month to avoid medication-overuse headache.

Dihydroergotamine Mesylate (Acute Migraine)

• Injection (IM/IV/SC): 1 mg initially, may repeat at 1-hour intervals. Maximum 3 mg/day IM/SC or 2 mg/day IV. Maximum 6 mg/week.
• Nasal spray (Migranal): 0.5 mg per nostril, repeated 15 minutes later (total 2 mg). Maximum 3 mg/24 hours, 4 mg/week.
• Nasal spray (Trudhesa): 0.725 mg per nostril (1.45 mg total). Single dose per attack.

Ergometrine/Methylergonovine (Postpartum Hemorrhage)

• Ergometrine: 0.2—0.5 mg IM or slow IV (obstetric emergency use).
• Methylergonovine (Methergine): 0.2 mg IM or oral, repeated every 2—4 hours as needed. Oral maintenance: 0.2 mg 3—4 times daily for up to 7 days.

Bromocriptine

• Hyperprolactinemia: Start 1.25 mg daily, titrate to 2.5—15 mg daily in divided doses.
• Type 2 diabetes (Cycloset): 0.8 mg daily, titrate weekly to 1.6—4.8 mg daily.

Cabergoline

• Hyperprolactinemia: 0.25 mg twice weekly initially, titrate to 0.25—2 mg twice weekly based on prolactin levels.

Crude Ergot (Historical Reference Only)

• Not used in modern medicine. Historical obstetric doses were approximately 1—4 grams of powdered ergot sclerotium, reflecting the extremely variable and dangerous nature of the crude preparation. Alkaloid content of sclerotia varies widely (0.01—0.5% total alkaloids by weight) depending on the host plant, Claviceps strain, climate, and storage conditions.

Sources

• Tfelt-Hansen PC, Koehler PJ. One hundred years of migraine research: major clinical and scientific observations from 1910 to 2010. Headache. 2011;51(5):752-778
• Silberstein SD, McCrory DC. Ergotamine and dihydroergotamine: history, pharmacology, and efficacy. Headache. 2003;43(2):144-166
• de Groot AN, van Dongen PW, Vree TB, Hekster YA, van Roosmalen J. Ergot alkaloids. Current status and review of clinical pharmacology and therapeutic use compared with other oxytocics in obstetrics and gynaecology. Drugs. 1998;56(4):523-535
• Schardl CL, Panaccione DG, Tudzynski P. Ergot alkaloids—biology and molecular biology. Alkaloids Chem Biol. 2006;63:45-86
• Berde B, Stürmer E. Introduction to the pharmacology of ergot alkaloids and related compounds. In: Ergot Alkaloids and Related Compounds. Springer; 1978:1-28
• Hofmann A. LSD: My Problem Child. McGraw-Hill; 1980
• Caporael LR. Ergotism: the satan loosed in Salem? Science. 1976;192(4234):21-26
• Spanos NP, Gottlieb J. Ergotism and the Salem Village witch trials. Science. 1976;194(4272):1390-1394
• Zanettini R, Antonini A, Gatto G, Gentile R, Tesei S, Pezzoli G. Valvular heart disease and the use of dopamine agonists for Parkinson’s disease. N Engl J Med. 2007;356(1):39-46
• Schiff PL. Ergot and its alkaloids. Am J Pharm Educ. 2006;70(5):98
• Lee MR. The history of ergot of rye (Claviceps purpurea) I: From antiquity to 1900. J R Coll Physicians Edinb. 2009;39(2):179-184
• Ergotamine/Caffeine. StatPearls. StatPearls Publishing; 2024

Connections

• Parasitic fungal pharmacology: Claviceps purpurea is a parasitic ascomycete that infects cereal grains, placing it in a fundamentally different ecological category from the saprophytic or mycorrhizal mushrooms that dominate this reference. Its closest parallel among listed species is Cordyceps, another parasitic ascomycete in the order Hypocreales that produces pharmacologically significant secondary metabolites (cordycepin). Both demonstrate how parasitic fungi — under intense evolutionary pressure from host defense systems — have evolved complex secondary metabolite profiles with potent biological activity.
• Vascular pharmacology: The vasoactive properties of ergot alkaloids (vasoconstriction via alpha-adrenergic and 5-HT1B/1D agonism) contrast with the cardiovascular-protective and blood-flow-enhancing properties attributed to mushrooms like Reishi (blood pressure reduction, platelet aggregation inhibition) and Auricularia auricula-judae (anticoagulant properties). Where these mushrooms generally promote vasodilation and improved circulation, ergot alkaloids produce vasoconstriction — therapeutically useful for migraine and hemorrhage but dangerous in excess.
• Pharmaceutical drug development from fungi: Claviceps purpurea represents the most productive example of pharmaceutical drug development from a fungal source in history, with at least six distinct marketed drug classes (ergotamine, DHE, ergometrine, bromocriptine, cabergoline, nicergoline) and the derivation of LSD. This track record underscores the pharmaceutical potential of fungal secondary metabolites and provides historical context for the current development of psilocybin-based therapeutics.
• Serotonergic receptor pharmacology: Ergot alkaloids interact with the same 5-HT2A receptors targeted by psilocybin, though they act as partial agonists with broader receptor profiles. Albert Hofmann’s synthesis of LSD from lysergic acid — and its profound 5-HT2A agonist effects — directly connects ergot pharmacology to the psychedelic research renaissance. The pharmacological sophistication of ergot alkaloids (simultaneously engaging serotonergic, dopaminergic, and adrenergic systems) illustrates the “dirty drug” paradigm that has been both a therapeutic advantage (multiple clinical applications) and a liability (unpredictable side effects).