Each patient will receive the usual migraine treatment: IV ketoprofen 100 mg and, if he suffers nausea and/or vomiting, additional IV metoclopramide 10 mg.
Depending on randomization assignment, patient will receive additional placebo (standard treatment arm) or additional IV Clorazepate 20 mg (study arm). The central pharmacy will be responsible for preparing the medications, using a double-blind protocol.
