Placebo-controlled study of gabapentin treatment of panic disorder

A randomized, double-blind, placebo-controlled, parallel-group study was conducted to evaluate the efficacy and safety of gabapentin in relieving the symptoms of panic disorder. One hundred three patients were randomly assigned to receive double-blind treatment with either gabapentin (dosed flexibly between 600 and 3,600 mg/day) or placebo for 8 weeks. No overall drug/placebo difference was observed in scores on the Panic and Agoraphobia Scale (PAS) (p = 0.606). A post hoc analysis was used to evaluate the more severely ill patients as defined by the primary outcome measure (PAS score greater than or equal to 20). In this population, the gabapentin-treated patients showed significant improvement in the PAS change score (p = 0.04). In patients with a PAS score of 20 or greater, women showed a greater response than men regardless of treatment. Adverse events were consistent with the known side effect profile of gabapentin and included somnolence, headache, and dizziness. One patient experienced a serious adverse event during the study. No deaths were reported. The results of this study suggest that gabapentin may have anxiolytic effects in more severely ill patients with panic disorder.