(FDA approved in bold)

• Migraine prophylaxis
  
• Cluster headache prophylaxis
  
• Diarrhea associated with carcinoid syndrome

• 5-HT2 and 5-HT1_A/B/C receptor antagonist and partial agonist of 5-HT1_B/D. It is unclear which action accounts for drug effectiveness
  
• Migraine/cluster: Proposed mechanisms include vasoconstrictive actions or inhibition of the release of inflammatory neuropeptides, such as calcitonin gene-related peptide. Prevention of cortical spreading depression may be the mechanism of action for all migraine preventatives

• Migraines – within 2 weeks, but can take up to 2 months on a stable dose to see full effect

• In migraine, the goal is a 50% or greater decrease in migraine frequency or severity. Consider tapering or stopping if headaches remit for more than 6 months or if considering pregnancy

• Increase to highest tolerated dose
  
• Migraine/cluster: address other issues such as medication-overuse, other coexisting medical disorders, such as anxiety, and consider changing to another drug or adding a second drug

• Migraine/cluster: Usually used in refractory cases of migraine and cluster headache, usually as an adjunctive agent. May use in combination with AEDs, antidepressants, natural products, and non-pharmacologic treatments, such as biofeedback, to improve headache control

• Monitor blood pressure. In patients on long-term continuous therapy, consider screening for fibrotic disorders