Methysergide Data - Uses, Dosage, Drug class, Brand name, Warnings, etc

Pharmacology	Methysergide is a semisynthetic ergot alkaloid, thought to act centrally as a serotonin agonist and to inhibit blood vessel permeability to humoral factors that affect pain threshold. Unlike other ergots, methysergide does not inhibit reuptake of norepinephrine and has minimal oxytocic, vasoconstrictor, and -adrenergic blocking effects. Because of its toxicity, methysergide is usually used only after other prophylactic measures have failed.
Adult Dosage	PO for migraine or cluster headache prophylaxis 4–8 mg/day with food. A drug-free interval of 3–4 weeks must follow each 6-month course; however, reduce the dosage gradually to avoid rebound headache.
Dosage Forms	Tab 2 mg.
Pharmacokinetics	Methysergide undergoes extensive liver metabolism to methylergonovine, a compound with greater activity and a longer elimination half-life than the parent drug (3.5 hr vs 1 hr). About 56% of an oral dose is eliminated in the urine as unchanged drug and metabolites.
Adverse Reactions	Insomnia, postural hypotension, nausea, vomiting, diarrhea, and peripheral ischemia occur frequently. Occasionally, heartburn, peripheral edema, rash, or arrhythmias occur. Rarely, mental depression occurs. Long-term (>6 months) therapy can cause retroperitoneal and pleuropulmonary fibrosis and thickening of cardiac valves.
Contraindications	Peripheral vascular, cardiovascular, or pulmonary disease; phlebitis; pregnancy; impaired liver or kidney function.
Precautions	Precautions and drug interactions are similar to those of ergotamine.

References

Hand of Clinical Drug Data