Open-label zonisamide for refractory migraine

Objectives: Zonisamide is a novel anticonvulsant drug with multiple mechanisms of action, many of which may confer efficacy in the treatment of migraine headaches. This study investigated the use of open-label zonisamide in treating patients with refractory migraine headaches. Methods: Thirty-four migraine patients were initiated on a 100-mg/day zonisamide dosage, which was titrated to 400 mg/day as tolerated. Mean headache severity, frequency, and duration were assessed before and 1, 2, and 3 months after initiation of zonisamide therapy. Results: Statistically significant improvements in headache severity (P < 0.01), duration (P < 0.05), and frequency (P < 0.05) were evident after 1 month of zonisamide therapy and were carried through month 3 of treatment. Zonisamide was well tolerated, with only 4 patients (11.8%) discontinuing for adverse events, including dysphoria (n = 2) and difficulty concentrating (n = 2). Other adverse events were transient and tolerable. Conclusions: These results suggest that zonisamide may be a safe and effective adjunctive agent for migraine prevention. Double-blind studies are warranted to confirm these findings.