Panic disorder: long-term pharmacotherapy and discontinuation

Abstract

This article compares panic disorder (PD) medications and discusses long-term therapy. In a review of the literature, monoamine oxidase inhibitors (MAOIs), selective serotonin reuptake inhibitors (SSRIs), and benzodiazepines prove effective in treating PD. MAOIs treat comorbid depression; frequent side effects are dizziness and orthostatic hypotension. SSRIs are better tolerated than MAOIs, producing mild anticholinergic effects, but also producing gastrointestinal side effects and sexual dysfunction. Benzodiazepines are generally well tolerated when titrated gradually; moderate sedation is the most common short-term side effect. Long-term risks are physical dependence and withdrawal reactions. One hundred six PD patients were enrolled in a double-blind, 8-month, placebo-controlled trial of alprazolam and imipramine. In the 8-week short-term phase, daily dosages were titrated up to 10 mg/day of alprazolam and 250 mg/day of imipramine. The greatest number of dropouts occurred during this phase (lack of improvement and/or side effects). Alprazolam patients had a significantly more rapid onset of improvement and lower adverse events and attrition rates. In the 6-month maintenance period, patients continued short-term treatment. Patients receiving either alprazolam or imipramine developed tolerance to some side effects. At maintenance-phase completion, 62% of the alprazolam-group patients and 26% of both the imipramine- and placebo-group patients were panic free (p<0.01). Dosages were tapered to zero over 3 weeks; one third of the alprazolam patients could not discontinue. During the unblinded, 15-month follow-up, patients received open treatment selected by personal physicians on an as-needed basis. At the end of follow-up, all patients were reassessed. Patients who had completed both short-term and maintenance phases were far more likely to be panic-free (85% vs. 55%; p<0.01). PD is chronic and recurrent, and 8 months is an effective treatment period. Maintenance treatment does not lead to tolerance, even with benzodiazepines. Dose tapering must be very gradual. Completion of a long-term maintenance program strongly predicts remission.