Methysergide.

Methysergide is a semisynthetic ergot alkaloid ergometrine derivative, introduced in pharmacotherapy for migraine prophylaxis as a specific serotonin (5HT) receptor antagonist. Methysergide is not just a 5HT2 antagonist, it is also a 5HT1 agonist. Open and controlled studies attest to methysergide's efficacy. It may be more effective in resistant cases with a high attack frequency and may act synergistically with ergotamine and dihydroergotamine (DHE) for breakthrough attacks. Contraindications include pregnancy, peripheral vascular disorders, severe arteriosclerosis, coronary artery disease, severe hypertension, thrombophlebitis or cellulitis of the legs, peptic ulcer disease, fibrotic disorders, lung diseases, collagen disease, liver or renal function impairment, valvular heart disease, debilitation, or serious infection. Methysergide can induce retroperitoneal fibrosis and pleural and heart valve fibrosis with an estimated incidence of 1 in 5,000 treated patients. Therefore, it should be reserved for severe cases in which other migraine preventive drugs are not effective.