Topiramate intervention to prevent transformation of episodic migraine: the topiramate INTREPID study.

OBJECTIVE: The study sought to evaluate whether topiramate prevents development of chronic daily headache (CDH, ≥15 headache days per month) in adult subjects with high-frequency episodic migraine (HFEM, 9-14 migraine headache days/month). A secondary objective was to assess the efficacy of topiramate as preventive migraine treatment in this population. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study comparing topiramate 100 mg/day and placebo for 26 weeks. The primary efficacy variable was new-onset CDH at month 6. Secondary efficacy measures included migraine and headache days. Adverse events (AEs) were evaluated. RESULTS: A total of 159 topiramate subjects and 171 placebo subjects were efficacy-evaluable. At month 6, 1.4% of topiramate subjects versus 2.3% of placebo subjects had CDH (p = .589). Compared with placebo, topiramate treatment was associated with statistically significant reductions in mean number of migraine days (6.6 vs. 5.3/28 days; p = .001) and headache days (6.6 vs 5.3/28 days; p = .001). Most commonly reported AEs in the topiramate versus placebo group included paresthesia (32.4% vs. 7.0%), fatigue (14.8% vs. 8.6%), dizziness (11.4% vs. 7.6%) and nausea (10.8% vs. 9.2%). CONCLUSION: Topiramate 100 mg/day did not prevent the development of CDH at six months in subjects with HFEM. Topiramate was effective in reducing headache days and migraine headache days and generally well tolerated.