Efficacy and Tolerability of Controlled-Release Paroxetine in the Treatment of Panic Disorder

Objective: To assess the efficacy and tolerability of controlled-release paroxetine (paroxetine CR) in the treatment of adults with panic disorder.

Method: Paroxetine CR (25-75 mg/day; N = 444) was compared with placebo (N = 445) in patients with DSM-IV panic disorder with or without agoraphobia in 3 identical, double-blind, placebo-controlled, 10-week clinical trials that were pooled for analysis.

Results: Paroxetine CR was statistically superior to placebo in the primary outcome measure, percentage of patients who were free of panic attacks in the 2 weeks prior to endpoint. Of the total population that completed or prematurely terminated treatment, 63% and 53% of paroxetine CR- and placebo-treated patients, respectively, were panic-free during the final 2 weeks (p < .005; odds ratio [OR] = 1.63; 95% CI = 1.21 to 2.19). For week 10 completers (72% of total), 73% and 60% of paroxetine CR- and placebo-treated patients, respectively, were panic-free at week 10 (p < .005; OR = 2.11; 95% CI = 1.45 to 3.07). Paroxetine CR was also statistically superior to placebo on the global improvement and severity items of the Clinical Global Impressions scale and in reducing anxiety symptoms as measured by the Hamilton Rating Scale for Anxiety total score and total fear and avoidance on the Marks-Sheehan Phobia Scale. Adverse events leading to study withdrawal were minimal and occurred in 11% of the paroxetine CR group and 6% of the placebo group. Most of the treatment-emergent adverse events were rated as mild to moderate in severity and occurred early in the study. There were no unexpected adverse events, and serious adverse events were uncommon (10 [2.3%] of the 444 patients treated with paroxetine CR vs. 8 [1.8%] of the 445 patients treated with placebo).

Conclusion: Paroxetine CR is an effective and well-tolerated treatment for panic disorder. Paroxetine CR is associated with low rates of treatment-emergent anxiety as well as low dropout rates from adverse events.