Serotonergic anxiolytics in the treatment of panic disorder: a controlled study with buspirone

The efficacy of buspirone for panic disorder was tested in 60 patients who met Diagnostic and Statistical Manual of Mental Disorders (3rd ed.) criteria for panic disorder or agoraphobia with panic attacks. Patients were randomly assigned to treatment with buspirone (mean dose 29.5 mg/day), imipramine (mean dose 140 mg/day), or placebo, and treated for 8 weeks after a 4- to 7-day placebo lead-in period. Patients with 4 or fewer attacks per month and those without attacks at the baseline visit were excluded from panic frequency comparisons. Both buspirone and imipramine tended to be better than placebo on total number of panic attacks, global psychopathology, and the Hamilton Anxiety rating scale, but end point differences among treatments were not statistically significant. At the end of the study, 25% of the buspirone patients were panic-free, as were 7% of the imipramine patients and 14% of the placebo patients; again, these differences were not statistically significant. The results of this study were inconclusive, partly because of the relatively small number of patients (10-11) completing the study in each treatment group, and partly because of a robust placebo response in this population. Possible reasons for this high placebo response are discussed, as well as suggestions for changes in study design for future studies.