The side effects burden of extended imipramine treatment of panic disorder

In a recent study, the authors gauged the net effectiveness of imipramine to be 53%; that is, of 110 patients having panic disorder with agoraphobia who started a course of imipramine at a fixed, targeted, weight-adjusted dose of 2.25 mg x kg(-1) x day(-1), 59 adhered to the regimen and showed a marked and stable response. The present study investigated in detail the side effects burden of imipramine treatment in the same sample using hierarchical linear modeling in a short-term perspective, based on data at baseline (N = 110) and at weeks 1, 2, 4, 6, and 8 (N = 77) of treatment, and a long-term perspective, based on data at baseline and at weeks 8, 16 (N = 66), and 24 (N = 59). Deviations from the general pattern were explored by considering only severe side effects or only completers of treatment to better gauge the clinical significance of the findings. The results revealed that of 15 complaints systematically elicited using a side effects inventory, only 3--dry mouth, sweating, and constipation--continued as a substantial burden at the end of 6 months of treatment. On most other items, the initial increase was followed by a decrease to lower than baseline at the end of treatment. In the case of nausea, vomiting, increased energy, headache, and sexual disorders, the complaints were at their worst before treatment started and improved over the course of treatment. A sustained heart rate elevation between 10 and 15 beats per minute was found, but there were no significant effects on blood pressure or weight. The discussion underscores the need for more methodologically improved comparative studies with selective serotonin reuptake inhibitors in the treatment of panic disorder.