Response to Phenelzine and Imipramine in Placebo Nonresponders With Atypical Depression A New Application of the Crossover Design

• We employed a study design that permitted a double-blind 12-week contrast of imipramine hydrochloride and phenelzine sulfate therapies in patients who met Columbia University criteria for atypical depression and were unresponsive to 7 weeks of treatment with placebo. These patients were found to benefit selectively from therapy with monoamine oxidase inhibitors compared with tricyclic drug therapy. This supports our observation about treatment response in depressed patients with reversed vegetative features. The design we utilized in this study has not previously been reported, to our knowledge. It was hypothesized that it would offer the advantage of the removal of a portion of placebo responders and serve to replicate our original findings. Treatment response to therapy with both imipramine and phenelzine in placebo nonresponders was uniformly lower (roughly 20% less than corresponding rates for patients who did not participate in the initial 6-week placebo trial). This is consistent with the view that the lower response rates were a result of the removal of some "placebo" responders in the drug groups. We think this is a useful design that should be considered in all studies of placebo and two active treatment regimens.