Methysergide maleate is a semisynthetic ergot alkaloid structurally related to methylergonovine by the presence of a methyl group on the nitrogen of the lysergic acid amide. It was introduced in the 1960s as a migraine prophylactic agent and was, for several decades, one of the most effective preventive treatments available for frequent disabling migraine. Its use is now heavily restricted in most countries because of the serious fibrotic toxicity syndrome — retroperitoneal and pleuropulmonary fibrosis — that develops with long-term continuous administration. Understanding methysergide remains pharmacologically important because its active metabolite, methylergonovine (methylergonovine maleate, also known as methylergometrine), is the same compound used in obstetrics, and the pharmacokinetic conversion of methysergide to methylergonovine in vivo is itself a model of pro-drug activation with distinct ADME implications for both parent compound and metabolite.
The absorption of methysergide after oral administration is rapid and virtually complete, with peak plasma concentrations (Cmax) reached within 60–90 minutes. Unlike ergotamine, which has poor and highly variable oral bioavailability (less than 1–5%) due to extensive first-pass cytochrome P450 3A4 (CYP3A4) metabolism and gastrointestinal wall extraction, methysergide achieves oral bioavailability of approximately 13–17% in most pharmacokinetic studies — low in absolute terms but substantially more reliable and predictable than ergotamine. The remaining absorbed fraction is removed by first-pass hepatic extraction through CYP3A4-mediated oxidative N-demethylation, which is simultaneously the primary metabolic pathway generating the active metabolite methylergonovine. Distribution is extensive; the volume of distribution (Vd) of methysergide is approximately 14–20 liters per kilogram, reflecting high lipophilicity and extensive tissue partitioning. Plasma protein binding is approximately 90%, primarily to albumin and alpha-1-acid glycoprotein (AAG). The elimination half-life of methysergide itself is relatively short at approximately 1 hour, but this is misleading as a guide to dosing because the active metabolite methylergonovine has a substantially longer half-life of approximately 2–3.5 hours, and it is the sustained methylergonovine plasma levels from repeated methysergide dosing (typically 1–2 mg three times daily) that maintain the pharmacodynamic effect.1
The metabolic conversion of methysergide to methylergonovine represents a first-pass bioactivation step that substantially determines the pharmacological profile of clinically administered methysergide. CYP3A4 in both the intestinal wall and the liver removes the N-methyl group from methysergide, producing methylergonovine in a reaction that is quantitatively the dominant metabolic fate of the drug. After oral methysergide administration, plasma concentrations of methylergonovine typically exceed those of parent methysergide within 1–2 hours and remain elevated for substantially longer due to methylergonovine's longer half-life. Pharmacokinetic studies estimate that 60–80% of the pharmacological activity of an oral methysergide dose is attributable to the methylergonovine metabolite rather than to methysergide itself. This bioactivation relationship has important clinical implications: CYP3A4 inhibitors that reduce methysergide clearance will simultaneously reduce methylergonovine formation, potentially altering both the pharmacodynamic effect and the toxicity profile; and the cardiovascular risks associated with methylergonovine (discussed in Ergot-04) are fully relevant to patients receiving methysergide, since plasma methylergonovine concentrations during methysergide therapy are comparable to those achieved with direct methylergonovine administration.1
The pharmacological mechanism underlying methysergide's prophylactic antimigraine efficacy is primarily antagonism at 5-HT2A and 5-HT2B receptors. Methysergide was historically described as a "serotonin antagonist" in contrast to the serotonin agonist properties of ergotamine; this simplification is pharmacologically inaccurate, as methysergide is actually a mixed agonist-antagonist at different serotonin receptor subtypes, but the antagonist component at 5-HT2A and 5-HT2B receptors in cranial blood vessels and trigeminal pain pathways is the mechanistically relevant action for migraine prevention. Methysergide reduces the amplitude and frequency of cortical spreading depression (CSD) — the electrophysiological event that correlates with migraine aura — through 5-HT2B receptor blockade in cortical tissue, and also inhibits the release of vasoactive neuropeptides from trigeminal perivascular nerve terminals through 5-HT receptor-mediated modulation of trigeminal afferent activity. Additionally, methysergide has high affinity for 5-HT1 receptors (both 1A and 1D subtypes), partial agonism at which may contribute to its vasomotor effects. The net pharmacodynamic profile of the methysergide-plus-methylergonovine system after oral dosing is complex, and the relative contributions of parent drug and metabolite to the overall prophylactic antimigraine effect have not been fully resolved in controlled clinical studies.1
Methysergide was withdrawn from the US market in 2002 by Novartis following declining use driven by fibrosis concerns, and it is unavailable in the United States. It remains available in limited form in some European and Canadian markets under restricted prescribing conditions, primarily for patients with chronic cluster headache (where its efficacy is well established and the frequency of prolonged continuous treatment is lower than for migraine prophylaxis) or refractory migraine in patients who have failed multiple other preventive agents. Where it is prescribed, the mandatory drug holiday regimen — discontinuing methysergide for at least 4 weeks every 6 months of treatment — is intended to allow regression of early fibrotic changes before they become clinically significant. Monitoring requires periodic chest X-ray and urinalysis (for fibrosis-related hydronephrosis) and abdominal examination. The development of newer migraine prophylactics (topiramate, valproate, beta-blockers, CGRP antagonists) has further reduced the clinical need for methysergide even in jurisdictions where it remains available.
The fibrotic complications of methysergide are pharmacologically among the most important adverse drug reactions in the history of ergot alkaloid use, not because of their frequency — which is relatively low, occurring in approximately 1 in 5,000 patients treated for more than 6 months — but because of the mechanistic insight they provided into the 5-HT2B receptor as a fibrogenic driver, which subsequently explained the valvulopathy associated with cabergoline, pergolide, and fenfluramine and became a required safety screen in drug development.
Retroperitoneal fibrosis (RPF) is a condition in which fibrous tissue accumulates in the retroperitoneal space, surrounding and eventually compressing the ureters, abdominal aorta, inferior vena cava, and other retroperitoneal structures. In methysergide-associated RPF, fibrogenesis is initiated and sustained by 5-HT2B receptor activation in retroperitoneal fibroblasts and myofibroblasts. The 5-HT2B receptor is expressed on mesenchymal cells in the retroperitoneum, and its Gq-coupled activation by methysergide (or by circulating methylergonovine generated from methysergide metabolism) stimulates fibroblast proliferation, collagen synthesis, and transforming growth factor-beta (TGF-beta) production — the same fibroproliferative cascade identified in cabergoline-associated cardiac valvulopathy and in carcinoid heart disease, where elevated circulating serotonin from enterochromaffin cell tumors drives identical fibrotic changes in cardiac valves, the endocardium, and sometimes the retroperitoneum. The distinction between methysergide-associated fibrosis (which affects primarily the retroperitoneum and pleura) and carcinoid heart disease or cabergoline-associated fibrosis (which affects primarily cardiac valves) reflects the tissue distribution of the fibrogenic stimulus rather than any difference in the underlying 5-HT2B-mediated mechanism.2
The clinical presentation of methysergide-associated RPF is typically insidious, developing over months to years of continuous treatment, and is often diagnosed late because the early symptoms are non-specific. The most common presenting manifestation is hydronephrosis secondary to ureteral entrapment by the retroperitoneal fibrotic mass, which causes flank pain, obstructive uropathy, and eventually impaired renal function if not recognized. Leg edema may occur if the inferior vena cava is compressed. Abdominal and lumbar pain radiating to the flank is a characteristic early symptom. Claudication of the lower extremities may develop if the iliac vessels are involved. Laboratory findings include elevated creatinine in advanced cases (from bilateral hydronephrosis), elevated erythrocyte sedimentation rate (ESR), and elevated C-reactive protein (CRP) reflecting the chronic inflammatory component of the fibrotic process. Computed tomography (CT) of the abdomen and pelvis is the primary diagnostic imaging modality, showing a periaortic soft-tissue density mass that wraps around and potentially obstructs the ureters; magnetic resonance imaging (MRI) is complementary, particularly for characterizing the degree of vascular involvement.3
Pleuropulmonary fibrosis (PPF) associated with methysergide presents with exertional dyspnea, pleuritic chest pain, and a pleural effusion detectable on chest radiography or CT. The mechanisms parallel those in the retroperitoneum: 5-HT2B-driven mesothelial and subpleural fibroblast activation produces pleural thickening and effusion. Pulmonary parenchymal fibrosis is less common than pleural disease in methysergide users, in contrast to idiopathic pulmonary fibrosis patterns; the distinction is important because methysergide-associated PPF is often partially or fully reversible after drug discontinuation, while true parenchymal fibrosis carries a worse prognosis. Other ergot dopaminergic agonists — particularly cabergoline and pergolide — can produce identical pleuropulmonary and retroperitoneal fibrotic changes through the same 5-HT2B mechanism, and published case series document RPF and PPF in patients receiving high cumulative doses of cabergoline for Parkinson's disease at rates comparable to those seen with historical methysergide use.4
Immediate and permanent discontinuation of methysergide is mandatory on identification of fibrosis. For retroperitoneal fibrosis, ureteral stenting or percutaneous nephrostomy is required for obstructive uropathy pending evaluation for definitive treatment. Surgical ureterolysis — release of the ureters from the surrounding fibrous mass with lateral repositioning — provides definitive relief in most cases. Corticosteroids (prednisone 40–60 mg daily, tapering over months) reduce the inflammatory component and may slow progression, but their effect on established fibrotic tissue is limited. Tamoxifen has been used as an anti-fibrotic agent in idiopathic and drug-associated RPF based on its anti-estrogenic effects on fibroblast proliferation, with variable results. Monitoring for recurrence of obstruction with periodic renal imaging is required for at least 5 years after drug discontinuation and surgical treatment, as the fibrotic process may persist or recur even after the causative agent is removed. For pleuropulmonary fibrosis, drug discontinuation alone produces regression of pleural effusion and pleural thickening in the majority of cases within 6–12 months.
Ergotism — systemic toxicity from excessive ergot alkaloid exposure — was a major cause of morbidity and mortality in medieval Europe, presenting in two distinct epidemic forms: gangrenous ergotism (St. Anthony's Fire), characterized by burning extremity pain followed by progressive peripheral ischemia and gangrene, and convulsive ergotism, characterized by seizures, paresthesias, and behavioral disturbances. Both syndromes resulted from chronic ingestion of Claviceps purpurea-contaminated rye grain, and they are of direct pharmacological relevance to modern clinicians because the drug toxicities described throughout this series are mechanistic extensions of the same underlying ergot pathophysiology operating at therapeutic or supra-therapeutic doses.
Gangrenous ergotism results from sustained peripheral vasoconstriction mediated by alpha-1 adrenergic receptor agonism and 5-HT2A receptor agonism in arterial smooth muscle, combined with direct vasoconstrictive effects of ergocryptine, ergocornine, and other ergopeptine alkaloids present in contaminated rye. Unlike the therapeutic ergot alkaloids used clinically, which are purified individual compounds, epidemic ergotism involved exposure to a complex mixture of ergot alkaloids in variable ratios from contaminated grain, and the additive vasoconstrictive effects of multiple alkaloids produced more severe and sustained vascular compromise than any single agent at therapeutic doses. The resulting arteriolar vasospasm reduces distal limb perfusion progressively, initially producing the burning ischemic pain that earned the condition its "St. Anthony's Fire" designation, then progressing to dry gangrene of the fingers, toes, ears, and nose as sustained ischemia causes tissue necrosis. The characteristic demarcation between ischemic and viable tissue is sharp, and affected extremities could autoamputate over weeks without surgical intervention.5
Convulsive ergotism, which predominated in some geographic regions and epidemic periods, involved a predominantly neurological syndrome with seizures, spasms, paresthesias, formication (the sensation of insects crawling on the skin, from Latin "formica," ant), and hallucinations. The mechanism of convulsive ergotism is not fully resolved but is thought to involve direct CNS toxicity from some ergot alkaloids — particularly ergonovine and its derivatives — through dopaminergic and serotonergic receptor activation in the central nervous system (CNS), producing excitation rather than the vasoconstriction-dominant picture of gangrenous ergotism. The geographic separation of gangrenous versus convulsive forms has been attributed to differences in the specific Claviceps purpurea strains and alkaloid compositions between European regions, as well as to dietary factors (vitamin A deficiency may predispose to convulsive forms). The distinction between the two syndromes illustrates the receptor pharmacological diversity within the ergot alkaloid class: the same class of fungal metabolites can produce predominantly vascular toxicity or predominantly CNS toxicity depending on the specific compound mixture and route of exposure.6
Modern clinical ergotism occurs in two principal scenarios. The first is iatrogenic ergotism from therapeutic overdose or, far more commonly, from drug-drug interactions that dramatically elevate ergot plasma concentrations — particularly the CYP3A4 inhibitor interactions detailed in Section 04, which convert a therapeutic dose of ergotamine into a toxic one. The second is ergotism from illicit ergot alkaloid exposure, primarily from the use of lysergic acid diethylamide (LSD), a semisynthetic ergot derivative, in doses that do not typically produce classical gangrenous ergotism but that can cause significant vasospasm, particularly in combination with other vasoconstrictive substances. The cardinal clinical features of iatrogenic ergotism requiring urgent recognition are: unexplained cold, painful, pale or mottled extremities in a patient receiving any ergot-containing medication; absent or markedly diminished peripheral pulses by Doppler examination despite palpable proximal pulses; and chest pain suggesting coronary vasospasm in a patient on ergotamine or ergot combination products. Each of these presentations warrants immediate ergot discontinuation and urgent vascular medicine or emergency medicine consultation.7
Identify and remove the ergot alkaloid immediately. Investigate for a precipitating CYP3A4 inhibitor started recently (macrolide antibiotic, azole antifungal, HIV protease inhibitor, grapefruit). Do not administer any further ergot dose. For peripheral vasospasm: IV sodium nitroprusside (titrated to restore perfusion, guided by Doppler signals) or IV prostaglandin E1 (alprostadil, 6–20 nanograms per kilogram per minute) is the vasodilatory treatment of choice. Alpha-adrenergic blockade with phentolamine provides partial relief by reversing the adrenergic vasoconstrictive component but does not address the 5-HT2A-mediated component. Anticoagulation with unfractionated heparin is initiated to prevent in situ thrombosis in ischemic vessels. Treatment duration follows pharmacodynamic recovery confirmed by Doppler, not plasma drug concentrations, because active metabolites can sustain vasospasm long after parent drug concentrations fall. Surgical or interventional vascular procedures may be required for refractory or advanced ischemia.
The CYP3A4 drug interaction is the single most dangerous pharmacokinetic interaction in ergot pharmacology and one of the most consequential drug interactions in all of clinical pharmacology. Its danger derives from a combination of factors that are rare in their coincidence: the ergot alkaloids have a pharmacokinetically narrow therapeutic window combined with steep concentration-effect relationships, CYP3A4 inhibitors are among the most commonly prescribed drug classes (macrolide antibiotics, azole antifungals), and the interaction can elevate ergot plasma concentrations by 10- to 40-fold, converting a dose that produces therapeutic antimigraine vasoconstriction into one that causes life-threatening peripheral and coronary arterial vasospasm.
Cytochrome P450 3A4 (CYP3A4) is the most abundant hepatic CYP enzyme, responsible for the oxidative metabolism of approximately 50% of all clinically used drugs. It is expressed at high levels in both the intestinal wall and the liver, and for drugs that are CYP3A4 substrates with significant oral first-pass extraction, intestinal wall CYP3A4 contributes substantially to overall pre-systemic clearance. Ergotamine and DHE are high-affinity CYP3A4 substrates with extensive first-pass extraction; the measurable oral bioavailability of ergotamine (1–5%) reflects the combined intestinal and hepatic CYP3A4 extraction. Methysergide, though having somewhat higher oral bioavailability (13–17%), is similarly CYP3A4-dependent for its clearance and for its bioactivation to methylergonovine. When a potent CYP3A4 inhibitor is administered concurrently, the inhibitor competes with the ergot substrate for the CYP3A4 active site through competitive inhibition, and for mechanism-based inhibitors (like erythromycin), covalently inactivates the enzyme, resulting in a reduction in the rate of ergot oxidative metabolism proportional to the degree of CYP3A4 inhibition. Because ergot bioavailability is already very low and is rate-limited by CYP3A4 extraction, even partial CYP3A4 inhibition produces disproportionately large increases in bioavailable ergot: reducing extraction from 98% to 80% (a seemingly modest change) increases bioavailability from 2% to 20%, a 10-fold increase.8
The macrolide antibiotics erythromycin and clarithromycin are the most clinically important CYP3A4 inhibitor class in ergot interaction pharmacology, because they are commonly prescribed for respiratory and dental infections and are frequently used in patients who may also be taking ergotamine for migraine prophylaxis or acute treatment. Erythromycin is both a competitive inhibitor and a mechanism-based inhibitor (MBI) of CYP3A4; it forms a stable nitrosoalkane complex with the ferrous heme iron of CYP3A4 after oxidative N-demethylation, irreversibly inactivating a fraction of available CYP3A4 enzyme. This irreversible component means that the interaction persists even after erythromycin is discontinued, until new CYP3A4 enzyme is synthesized (a process requiring approximately 24–72 hours). Clarithromycin shares this mechanism-based inhibition profile and is similarly potent. Azithromycin, a structurally distinct macrolide, does not inhibit CYP3A4 significantly and does not carry the ergot interaction risk — an important practical distinction when antibiotic choice is being made for a patient on ergot therapy. FDA prescribing information for ergotamine and DHE explicitly lists erythromycin and clarithromycin as absolute contraindications.9
The azole antifungals — ketoconazole, itraconazole, voriconazole, fluconazole, and posaconazole — are potent competitive CYP3A4 inhibitors that elevate ergot plasma concentrations by blocking the oxidative clearance pathway. Ketoconazole is the reference CYP3A4 inhibitor in drug interaction pharmacology, producing approximately 90% inhibition of CYP3A4 activity at standard clinical doses. Itraconazole and voriconazole are comparably potent. Fluconazole, though primarily a CYP2C9 inhibitor, also inhibits CYP3A4 at standard doses and should be considered a significant ergot interaction risk. Topical azole preparations (clotrimazole cream, topical fluconazole) do not achieve systemic concentrations sufficient to meaningfully inhibit hepatic CYP3A4 and do not carry the ergot interaction risk. HIV protease inhibitors — ritonavir, lopinavir, atazanavir, indinavir — are potent CYP3A4 inhibitors, and ritonavir, which is used as a pharmacokinetic booster at sub-therapeutic antiviral doses to enhance the plasma levels of other protease inhibitors and integrase inhibitors, is perhaps the most potent CYP3A4 inhibitor encountered clinically. Any patient taking ritonavir (or cobicistat, another pharmacokinetic booster with similar CYP3A4 inhibitory potency) must not receive any ergot alkaloid.8
Grapefruit and grapefruit juice contain furanocoumarins (principally bergamottin and 6,7-dihydroxybergamottin) that are mechanism-based inactivators of intestinal CYP3A4 — not hepatic CYP3A4, which they do not reach at concentrations achievable by oral ingestion. Because intestinal CYP3A4 contributes substantially to first-pass extraction of ergot alkaloids, regular grapefruit consumption can increase ergot bioavailability by 1.5- to 3-fold in pharmacokinetic studies, a more modest elevation than the 10- to 40-fold increases produced by macrolides or azoles, but clinically meaningful enough to potentially push ergot plasma concentrations into the toxic range in a patient already near the upper limit of the therapeutic dose range. Patients receiving ergotamine or DHE should be advised to avoid grapefruit and grapefruit juice throughout their course of treatment. The duration of the intestinal CYP3A4 inactivation by a single glass of grapefruit juice extends to 24–72 hours because it requires synthesis of new intestinal CYP3A4 enterocytes, not merely clearance of the inhibitor from circulation.
The clinical management of known or suspected CYP3A4-ergot interactions requires a tiered approach based on the severity of the interaction. For potent inhibitors (macrolides, azoles, HIV protease inhibitors, cobicistat): the ergot alkaloid is absolutely contraindicated and must not be co-prescribed. If a patient develops a migraine headache while receiving one of these agents, the ergot cannot be used; triptans are the appropriate alternative for acute treatment, and prophylactic options include beta-blockers, valproate, or topiramate, none of which are CYP3A4 substrates. For moderate CYP3A4 inhibitors (diltiazem, verapamil, fluconazole at doses above 50 mg): dose reduction of the ergot and enhanced monitoring for toxicity symptoms (extremity coldness, pain, claudication, chest pain) are appropriate, with a low threshold to discontinue the ergot. For grapefruit: avoidance instruction is adequate. For all patients on ergot therapy: a medication reconciliation check at each visit specifically reviewing for new CYP3A4 inhibitors, and explicit patient education that they must not take a new prescription or non-prescription drug without checking with their prescriber first, because numerous over-the-counter and complementary medications have CYP3A4 inhibitory activity.10
The ergot alkaloid series spans vasomotor pharmacology, obstetric pharmacology, dopaminergic neuropharmacology, and toxicology. What unites this pharmacologically diverse class is the ergoline ring system — a tetracyclic scaffold that presents different receptor-binding surfaces depending on the nature of the substituent at C-8, allowing individual ergot alkaloids to differ substantially in receptor selectivity while sharing fundamental structural features that drive certain class-wide pharmacological properties, chief among them the propensity for receptor partial agonism, the susceptibility to CYP3A4 metabolism, and the 5-HT2B-mediated fibrogenic potential that varies in magnitude across the class.
The receptor pharmacological diversity of the ergot alkaloids arises from differences in the C-8 substituent rather than from differences in the ergoline core. Simple amide substituents (as in ergometrine and methylergonovine) confer predominantly uterotonic and relatively modest vasoconstrictive activity, with high alpha-1 AR and 5-HT2A agonism but low D2 activity. Methylation of the amide nitrogen (as in methysergide relative to methylergonovine) shifts the pharmacological profile toward 5-HT antagonism and introduces the fibrogenic 5-HT2B agonist activity that causes retroperitoneal fibrosis. Tripeptide substituents (as in ergotamine) produce broad multi-receptor activity across alpha-ARs, 5-HT receptors, and D2 receptors, with high vasoconstriction risk and the complex pharmacokinetic profile of extreme first-pass extraction. Modified peptide substituents (as in cabergoline, with its carbethoxy-aminoethyl-urea chain) shift selectivity dramatically toward D2 receptors while reducing alpha-AR and 5-HT1 activity, producing the dopaminergic ergot profile. The introduction of a bromine at C-2 of the lysergic acid ring (as in bromocriptine) further enhances D2 selectivity. This structure-activity relationship across the series illustrates a generalizable pharmacological principle: within a class of compounds sharing a common scaffold, substituent engineering can selectively alter receptor binding without eliminating class-level pharmacokinetic properties such as CYP3A4 dependence.11
The class-wide susceptibility to CYP3A4-mediated drug interactions reflects the structural vulnerability of the ergoline ring and its substituents to CYP3A4 oxidation, which is a property of the ergoline scaffold rather than of any particular substituent. All clinically used ergot alkaloids — ergotamine, DHE, ergometrine, methylergonovine, methysergide, bromocriptine, and cabergoline — are CYP3A4 substrates, though the degree of first-pass extraction varies substantially from drug to drug. The therapeutic consequence of this class-wide CYP3A4 susceptibility is that clinicians prescribing any ergot alkaloid must maintain awareness of CYP3A4 inhibitors as potential precipitants of toxicity — not only for the vasoactive ergots (where the toxicity is acute and severe) but also for the dopaminergic ergots (where CYP3A4 inhibitors can elevate cabergoline plasma concentrations, intensifying both its prolactin-suppressive effect and its 5-HT2B-mediated cardiac valvulopathy risk). The shared pharmacokinetic vulnerability does not eliminate the pharmacodynamic differences between subclasses, but it means that the same drug interaction awareness must be applied across the entire clinical ergot repertoire.8
The 5-HT2B receptor agonism that underlies both methysergide-associated retroperitoneal fibrosis and cabergoline/pergolide-associated cardiac valvulopathy represents the most pharmacologically instructive toxicological theme of the ergot series. Prior to the recognition that drug-associated valvulopathy shared its mechanism with carcinoid heart disease — itself a natural experiment in chronic 5-HT2B stimulation — the fibrogenic role of 5-HT2B receptors was not appreciated in drug safety assessment. The ergot-associated fibrosis syndromes catalyzed a fundamental reorientation in pharmaceutical safety pharmacology: 5-HT2B receptor agonist activity is now a mandatory screening endpoint for all new chemical entities intended for chronic use, and compounds that show meaningful 5-HT2B agonism at concentrations near their therapeutic range are typically advanced into development only with an explicit fibrosis risk management strategy. This transformation of toxicological understanding — from observing an adverse effect in the clinic to identifying the molecular target to establishing a new safety screening standard — exemplifies the broader pharmacological value of understanding drug toxicity mechanistically rather than descriptively.2
Ergot-01: Ergoline scaffold, receptor diversity, structural determinants of selectivity. Natural (ergotamine, ergometrine) vs. semisynthetic (DHE, methysergide, bromocriptine, cabergoline). Alpha-AR, 5-HT, D2 receptor affinity profiles by subclass.
Ergot-02: Ergotamine and DHE in migraine. Trigeminovascular pathophysiology. Pharmacokinetics by route — extreme first-pass, rectal 20× oral, DHE 8-OH-DHE active metabolite. Contraindications, CYP3A4 absolute prohibition, ergot-triptan 24-hour rule, MOH threshold.
Ergot-03: Dopaminergic ergots. D2 signal transduction. Bromocriptine ADME (5–6% bioavailability, CYP3A4, beta-phase t½ 50 h). Cabergoline ADME (Vd 115 L/kg, t½ 63–109 h, reduced CYP3A4 dependence, twice-weekly dosing). Indications, NMS, T2DM. 5-HT2B valvulopathy — dose-dependent, cumulative >3 g threshold, echocardiographic monitoring. Pergolide withdrawal, DAWS, ICDs.
Ergot-04: Uterotonic ergots. Alpha-1 AR + 5-HT2A myometrial mechanism. Estrogen priming. Methylergonovine ADME (60% oral bioavailability, Vd 39–73 L/kg, t½ 2–3.5 h). IV route emergency-only. WHO and ACOG PPH protocols. Ergometrine vs. methylergonovine. Cardiovascular absolute contraindications.
Ergot-05: Methysergide ADME (bioactivation to methylergonovine by CYP3A4 N-demethylation; t½ methysergide ~1 h, methylergonovine 2–3.5 h). Retroperitoneal and pleuropulmonary fibrosis. Gangrenous vs. convulsive ergotism. CYP3A4 interaction mechanistic basis. Structure-activity synthesis.
Silberstein SD. Methysergide. Cephalalgia. 1998;18(7):421–435.
doi:10.1046/j.1468-2982.1998.1807421.xRoth BL. Drugs and valvular heart disease. N Engl J Med. 2007;356(1):6–9.
doi:10.1056/NEJMp068265Vaglio A, Salvarani C, Buzio C. Retroperitoneal fibrosis. Lancet. 2006;367(9506):241–251.
doi:10.1016/S0140-6736(06)68035-5Antonini A, Poewe W. Fibrotic heart-valve reactions to dopamine-agonist treatment in Parkinson's disease. Lancet Neurol. 2007;6(9):826–829.
doi:10.1016/S1474-4422(07)70218-1Schiff PL. Ergot and its alkaloids. Am J Pharm Educ. 2006;70(5):98.
doi:10.5688/aj700598Matossian MK. Poisons of the Past: Molds, Epidemics, and History. New Haven, CT: Yale University Press; 1989. ISBN 978-0300048766.
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.
doi:10.2165/00003495-199856040-00002Dresser GK, Spence JD, Bailey DG. Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition. Clin Pharmacokinet. 2000;38(1):41–57.
doi:10.2165/00003088-200038010-00003Westphal JF. Macrolide-induced clinically relevant drug interactions with cytochrome P-450A (CYP) 3A4: an update focused on clarithromycin, azithromycin and dirithromycin. Br J Clin Pharmacol. 2000;50(4):285–295.
doi:10.1046/j.1365-2125.2000.00261.xSilberstein SD, McCrory DC. Ergotamine and dihydroergotamine: history, pharmacology, and efficacy. Headache. 2003;43(2):144–166.
doi:10.1046/j.1526-4610.2003.03034.xSchiff PL. Ergot and its alkaloids. Am J Pharm Educ. 2006;70(5):98.
doi:10.5688/aj700598