Evidence based migraine prophylactic drug therapy.

Prophylactic drug therapy is a major component of overall migraine management. However, because we do not know how currently used prophylactic drugs exert their beneficial effects in migraine, their use is based primarily on clinical trials. In general, prophylactic drugs are indicated when patients have three or more attacks a month and symptomatic medication use alone is not satisfactory. The choice of drug must be individualized, and is influenced by contraindications, potential side effects, the need to treat associated symptoms like tension-type headache and insomnia, and drug cost. Whether an individual patient will respond to a given drug cannot be predicted, but there are varying degrees of scientific evidence supporting the use of each prophylactic drug in migraine. This evidence is best for metoprolol, divalproex, amitriptyline, atenolol, flunarizine and naproxen. Based on placebo-controlled crossover studies, it would appear that at least some prophylactic drugs exert the greater part of their prophylactic effects very quickly, and that these also disappear very quickly once the drug is stopped. This may not apply to all prophylactic drugs and more research is needed. More well designed clinical trials are needed to guide our use of migraine prophylactic drugs. Although clinical experience is useful, placebo responses and variations in the migraine tendency over time can make interpretation of this experience difficult. Major advances will likely only occur once the pathogenesis of migraine and the mode of action of the prophylactic drugs is better understood.