Efficacy of Divalproex Sodium in Patients with Panic Disorder and Mood Instability Who Have Not Responded to Conventional Therapy

OBJECTIVE: To determine the efficacy of divalproex sodium in the treatment of psychiatric outpatients with treatment refractory panic disorder and comorbid mood instability. METHOD: This was an 8-week, open-trial, flexible-dose outcome study conducted at a tertiary care referral centre. Individuals with panic disorder who failed to respond to a cognitive behavioural treatment program and standard antipanic medication, who also suffered from mood instability, were chosen to participate in the study. Divalproex sodium was administered at a flexible dose to reach serum levels of 300 to 600 mumol/L (45 to 90 ug/ml) unless limited by tolerance. Patients were rated by self- and rater-administered questionnaires that measured the number of panic attacks, the degree of agoraphobic avoidance, the levels of depression, anxiety, and mood swings, and the perceived sense of well being. RESULTS: Thirteen subjects were enrolled in the study, and 10 subjects completed it. Two dropped out early because of the medication's side effects, and 1 was lost within the first month of follow-up. All 10 subjects showed significant improvement in depressive and anxiety symptoms and mood instability. There was also a statistically and clinically significant improvement in panic attacks and measures of quality of life. CONCLUSIONS: These findings suggest that divalproex sodium is useful in the treatment of patients with panic disorder and concomitant mood instability, who are refractory to conventional treatment. Double-blind trials will be required to verify these findings.