Dihydroergotamine

Dihydroergotamine exerts its therapeutic effect primarily through agonist activity at serotonin 5-HT1B and 5-HT1D receptors located on intracranial blood vessels and trigeminal nerve endings. This activation leads to cranial vasoconstriction and inhibition of the release of vasoactive neuropeptides such as calcitonin gene-related peptide (CGRP), thereby aborting migraine attacks.¹ Unlike ergotamine, DHE has reduced affinity for alpha-adrenergic receptors, resulting in less peripheral vasoconstriction and a lower risk of ergotism.² The drug also interacts with dopamine receptors, which may contribute to its antiemetic properties but also to side effects like nausea. Its long half-life (approximately 10 hours) and active metabolite, 8'-hydroxy-DHE, prolong its action, making it suitable for treating refractory headaches.³

DHE is indicated for the acute treatment of migraine with or without aura and cluster headaches. Clinical trials have demonstrated that intravenous DHE is highly effective in terminating migraine attacks, with response rates exceeding 70% in some studies.⁴ The intranasal formulation offers a convenient non-invasive option, though its bioavailability is lower (~32%) compared to parenteral routes.⁵ DHE is particularly valuable for patients who do not respond to triptans or who experience prolonged migraines lasting more than 24 hours. In cluster headache management, subcutaneous or intramuscular DHE can rapidly abort attacks. The American Headache Society recommends DHE as a first-line therapy for acute migraine in emergency settings.⁶

Common adverse effects include nausea, vomiting, dizziness, and injection-site reactions. Nausea can be mitigated by co-administering an antiemetic such as metoclopramide.⁷ Serious but rare risks include coronary vasospasm, myocardial infarction, and cerebrovascular events, particularly in patients with underlying cardiovascular disease. DHE is contraindicated in individuals with ischemic heart disease, peripheral vascular disease, uncontrolled hypertension, or a history of stroke. It is also contraindicated within 24 hours of taking a triptan due to additive vasoconstrictive effects. Because DHE is an ergot derivative, prolonged use can lead to ergotism, characterized by gangrene and confusion, though this is exceedingly rare with modern dosing. Pregnancy category X is assigned, as DHE can induce uterine contractions and fetal harm.

Beyond headache treatment, DHE has been explored for managing orthostatic hypotension due to its venoconstrictor effects, though results have been mixed.³ It has also been studied as an adjunct in opioid withdrawal protocols, where its serotonergic activity may reduce craving. Historically, DHE was synthesized by Albert Hofmann, the discoverer of LSD, at Sandoz Laboratories in 1943.² The intranasal spray formulation, approved in 1997, was a significant innovation, but its use declined with the advent of triptans. However, DHE remains a critical rescue medication for status migrainosus. A novel orally inhaled DHE (MAP0004) was developed and showed rapid onset, but it did not gain widespread adoption. DHE's long duration of action makes it useful for preventing headache recurrence, a common limitation of triptans.

Ergot alkaloid

A class of compounds derived from the ergot fungus, with vasoconstrictive and serotonergic properties.

5-HT1B/1D receptors

Serotonin receptor subtypes that mediate cranial vasoconstriction and inhibition of neuropeptide release.

Status migrainosus

A severe migraine attack lasting more than 72 hours, often requiring emergency treatment.

Triptan

A class of drugs that selectively activate 5-HT1B/1D receptors, used for acute migraine.