Open-Label Adjunctive Zonisamide in the Treatment of Bipolar Disorders: A Prospective Trial
J Clin Psychiatry 2005;66(5):617-624
© Copyright 2014 Physicians Postgraduate Press, Inc.
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Background: The response of 62 outpatients with
DSM-IV bipolar disorders to open-label adjunctive zonisamide was
evaluated in a prospective 8-week acute trial, followed by a
48-week continuation trial, conducted from June 2001 through May
Method: During the acute trial, response to
zonisamide was assessed weekly for the first 4 weeks and every 2
weeks for the second 4 weeks with the Clinical Global Impressions
scale modified for bipolar illness (CGI-BP), the Young Mania
Rating Scale (YMRS), and the Inventory for Depressive
Symptomatology (IDS). During the continuation trial, patients
were assessed with these scales every 4 weeks. Patients' weights
and side effects were also evaluated. Outcome measures were
analyzed with repeated-measures analyses of variance.
Results: Patients with manic symptoms at study
entry (N = 34) displayed significant reductions in CGI-BP-Mania
Severity and YMRS scores in the acute and continuation (N = 19)
trials (p values < .0001 and < .001, respectively). Patients
with depressive symptoms at study entry (N = 22) showed significant
decreases in CGI-BP-Depression Severity and IDS scores in the
acute trial (p values < .001 and < .05, respectively), but
only 9 patients entered the continuation trial. Among these 9
patients, maintenance of antidepressant response was mostly
maintained. Initially euthymic patients (N = 6) showed no change in
any rating scale scores acutely, but 2 of 4 patients who entered
the continuation trial developed depressive symptoms. The 62
patients as a group showed significant weight loss in both trials
(p values < .001). However, 20 patients (32%) discontinued zonisamide for worsening mood symptoms.
Conclusion: Adjunctive zonisamide was associated
with beneficial effects on mood and body weight in some patients
with bipolar disorders, but was also associated with a high
discontinuation rate due to worsening mood symptoms.
Double-blind, placebo-controlled studies are necessary to
determine zonisamide's thymoleptic properties, if any, in bipolar