<unk> (sublingual tablet) is an alpha adrenergic blocking agent that is FDA approved for the prophylaxis of vascular migraine. There is a Black Box Warning for this drug as shown here.  Common adverse reactions include pruritus, nausea and vomiting, muscle weakness, paresthesia and visual disturbance.
Ergotamine tartrate 
Metergoline
Penbutolol
Avacopan
Nicergoline
Terguride
Bietaserpine
Cabergoline