(FDA approved in bold)

• Migraine prophylaxis
  
• Vasospasm in subarachnoid hemorrhage
  
• Adjunctive drug for epilepsy
  
• Vertigo
  
• Alternating hemiplegia of childhood
  
• Tourette’s syndrome
  
• Tinnitus

• Migraine/cluster: Proposed prior mechanisms included inhibition of smooth muscle contraction preventing arterial spasm and hypoxia, prevention of vasoconstriction or platelet aggregation, and alterations of serotonin release and uptake
  
• Prevention of cortical spreading depression may be the mechanism of action for all migraine preventives
  
• May also interact with other neurotransmitters, and may inhibit the synthesis and release of nitric oxide
  
• The drug also appears to act by blocking dopamine D2 receptors in a manner similar to antipsychotics

• Migraines may decrease in as little as 2 weeks, but can take up to 2 months to see full effect

• Migraine – 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 patient considering pregnancy

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

• Migraine: For some patients with migraine, low-dose polytherapy with 2 or more drugs may be better tolerated and more effective than high-dose monotherapy. May use in combination with AEDs, antidepressants, natural products, and non-medication treatments, such as biofeedback, to improve headache control

• Monitor ECG for PR interval