Ergotamine is a potent vasoconstrictor alkaloid derived from the ergot fungus (Claviceps purpurea). It is a first-line abortive therapy for acute migraine and cluster headaches, acting primarily on serotonin (5-HT1B/1D) receptors and alpha-adrenergic receptors. Its use is strictly limited due to the risk of severe vasospasm, ergotism, and medication-overuse headache. In India, it is a Schedule H drug, available primarily in fixed-dose combinations with caffeine for oral use, though its use has declined in favor of triptans.
Adult: For Migraine: 2mg at onset of attack, followed by 1mg every 30 minutes if needed. MAXIMUM: 6mg per attack, 10mg per week. Often formulated as Ergotamine Tartrate 1mg + Caffeine 100mg tablet: 2 tablets at onset, then 1 tablet every 30 min (max 6 tablets/attack, 10 tablets/week).
Note: Take at the FIRST SIGN of a migraine headache. Take with food or milk to reduce GI upset. Do not crush or chew sublingual tablets. For optimal absorption, avoid taking with grapefruit juice. Do not use on a daily basis. Maintain a headache diary to monitor frequency.
Ergotamine exerts its therapeutic effect in migraine through a complex mechanism involving cranial vasoconstriction and inhibition of neurogenic inflammation. It binds with high affinity to serotonin 5-HT1B receptors on smooth muscle cells of intracranial extracerebral blood vessels, causing vasoconstriction of dilated vessels during a migraine attack. It also agonizes 5-HT1D receptors on trigeminal nerve terminals, inhibiting the release of vasoactive neuropeptides like CGRP and substance P, thereby reducing neurogenic inflammation and pain transmission.
Pregnancy: Category X. Contraindicated. Ergotamine is a known abortifacient and oxytocic agent. It can cause fetal distress, intrauterine growth restriction, and spontaneous abortion due to uterine contractions and placental vasoconstriction.
Driving: May cause dizziness, drowsiness, or blurred vision. Patients should be cautioned against driving or operating machinery until they know how the drug affects them.
| CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Clarithromycin, Erythromycin, Ritonavir, Saquinavir) | Dramatically increases ergotamine plasma levels, leading to life-threatening vasospasm and ischemia. | Contraindicated |
| Beta-blockers (Propranolol, Metoprolol) | Potentiates vasoconstrictive effects, increasing risk of peripheral ischemia. | Major |
| Other Vasoconstrictors (Triptans - Sumatriptan, NSAIDs in high doses) | Increased risk of prolonged vasospasm and hypertension. A 24-hour gap is recommended between ergotamine and triptan use. | Major |
| Nicotine (Smoking) | Enhances vasoconstrictive effect, increasing ischemic risk. | Moderate |
| Macrolide antibiotics (Clarithromycin, Erythromycin) | CYP3A4 inhibition leading to toxicity. | Contraindicated |
| Nitrates (Nitroglycerin) | Theoretical antagonism of anti-anginal effect. | Moderate |