Background: Open-label trials and small controlled studies report topiramate's efficacy in migraine prevention.
Objective: To assess the efficacy and safety of topiramate as a migraine-preventive therapy.
Design: A 26-week, randomized, double-blind, placebo-controlled study.
Setting: Outpatient treatment at 49 US clinical centers. Patients Patients were aged 12 to 65 years, had a 6-month International Headache Society migraine history, and experienced 3 to 12 migraines per month, but had 15 or fewer headache days per month during the 28-day baseline period.
Interventions: Participants were randomized to placebo or topiramate, 50, 100, or 200 mg/d, titrated by 25 mg/wk to the assigned dose or as tolerated in 8 weeks; maintenance therapy continued for 18 weeks.
Main outcome measures: The primary efficacy assessment was a reduction in mean monthly migraine frequency across the 6-month treatment phase. Secondary end points were responder rate, time to onset of action, mean change in migraine days per month, and mean change in rescue medication days per month.
Results: Four hundred eighty-seven patients were randomized, and 469 composed the intent-to-treat population. The mean +/- SD monthly migraine frequency decreased significantly for the 100-mg/d group (from 5.4 +/- 2.2 to 3.3 +/- 2.9; P <.001) and the 200-mg/d group (from 5.6 +/- 2.6 to 3.3 +/- 2.9; P <.001) vs the placebo group (from 5.6 +/- 2.3 to 4.6 +/- 3.0); improvements occurred within the first treatment month. Significantly more topiramate-treated patients (50 mg/d, 35.9% [P =.04]; 100 mg/d, 54.0% [P <.001]; and 200 mg/d, 52.3% [P <.001]) exhibited a 50% or more reduction in monthly migraine frequency than placebo-treated patients (22.6%). Adverse events included paresthesia, fatigue, nausea, anorexia, and taste per version.
Conclusion: Topiramate, 100 or 200 mg/d, was effective as a preventive therapy for patients with migraine.