Dose-response characterization of the antipanic effects of imipramine.

This article presents panic diary results of a dose-response study with imipramine hydrochloride in panic disorder with agoraphobia patients. Analysis of variance revealed significant time effects on panic frequency and severity measures, but group x time interaction effects were present for the severity measures only. Results also provided evidence for a positive dose-response relationship with 20 percent of patients in the placebo group, 31 percent in the low-dose group (0.5 mg/kg/day), 54 percent in the medium-dose group (1.5 mg/kg/day), and 70 percent in the high-dose (3 mg/kg/day) group being free of recurrent or severe panic attacks at posttreatment. Further stratified and logistic regression analyses revealed a direct linear relationship between total plasma tricyclic concentration and response. These findings affirm the dose-dependent nature and the specificity of imipramine's antipanic effects.