• anticonvulsants;
  • bipolar disorder;
  • zonisamide

Background:  This retrospective chart review evaluated the use of zonisamide as adjunctive treatment in patients with bipolar depression.

Method:  The charts of outpatients with bipolar I or II disorder treated with adjunctive zonisamide were reviewed. The efficacy of zonisamide was assessed via comparison of physician-rated Global Assessment of Functioning (GAF) and Clinical Global Impression of Severity (CGI-S) Scale scores at baseline and after 6 weeks of therapy using paired t-tests. Patients who scored ≤2 on the CGI-S after 6 weeks of zonisamide therapy were considered good responders to zonisamide.

Results:  Charts for 12 patients (four men and eight women) with a mean (±SD) age of 39.6 (±7.6) years were evaluated. Patients received a mean (±SD) zonisamide dosage of 236 (±68) mg/day. Mean GAF scores significantly improved from 44.0 at baseline to 59.3 at week 6 (P = 0.05). Mean CGI-S scores improved from 4.54 at baseline to 3.42 at week 6, but the change was not statistically significant. Six patients (50.0%) were considered responders to zonisamide. Four patients discontinued zonisamide therapy, two for an adverse event (sedation) and two for lack of efficacy.

Conclusions:  Zonisamide may be a useful adjunctive treatment for some patients with bipolar depression. Conclusions from this study are limited due to its retrospective design. Further investigation of zonisamide in the treatment of bipolar depression is warranted.