• chronic daily headaches;
  • migraine;
  • divalproex sodium;
  • long-term treatment

Objective.—The purpose of this study was to assess the safety and efficacy of divalproex sodium in the long-term treatment of chronic daily headache. Correlations between treatment variables were assessed.

Background.—Controlled and open-label trials of divalproex sodium have previously demonstrated its efficacy and safety in the treatment of migraine and chronic daily headaches. These data were primarily short-term and did not examine interaction between treatment variables.

Methods.—Retrospective chart review with data extraction was conducted from headache diaries of 642 current patients under treatment with divalproex sodium for chronic daily headaches. One hundred thirty-eight of the patients were treated with only divalproex sodium. Demographic variables including age, sex, initial and final body weights, adverse events, dose of divalproex sodium, duration of treatment, and the ability to differentiate their chronic daily headache into its migraine and tension-type headache components were analyzed. Baseline and end of study headache frequency indices were obtained.

Results.—The mean improvement was 47%, with an improvement in migraine of about 65%. At least a 50% reduction in headache frequency was reported by 93 of the 138 patients receiving treatment with only divalproex sodium. No correlation between response and age, sex, duration of treatment, and the prescribed dose of divalproex sodium was demonstrated. Adverse events occurred in approximately 35% of the patients. None were severe. Women were more likely to experience adverse effects than men. Weight gain, however, occurred less commonly in women (mean, 1.9 lbs) than in men (mean, 7 lbs). Initial body weight and age did not correlate with the weight change.

Conclusions.—Divalproex sodium can be used for a prolonged period as a sole agent for the successful treatment of chronic daily headache. Nearly 75% of the patients had at least a 50% reduction in headache frequency, and adverse effects occurred in approximately one third. Weight gain was negligible and hepatotoxicity did not occur during treatment periods of up to 6 years.