Long-term treatment of anxiety disorders with pregabalin: a 1 year open-label study of safety and tolerability

Objective: Short-term clinical trials have demonstrated the efficacy and safety of pregabalin in the treatment of generalized anxiety disorder (GAD). This study examined long-term safety and tolerability of pregabalin in patients with GAD, social anxiety disorder (SAD), or panic disorder (PD). Research design and methods: Patients (n=528) completing one of four randomized, double-blind, placebo-controlled trials of pregabalin for GAD, SAD, or PD were treated, open label, with flexible-dose pregabalin (150-600 mg/day) for 1 year. Clinical trial registration: NCT00150449. Main outcome measures: The primary outcomes were safety and tolerability. Illness severity was assessed at baseline and Weeks 27/52 using the Clinical Global Impression of Severity (CGI-S) scale. Patients were characterized as 'responders' or 'non-responders' based on CGI-S scores <= 2 and >2, respectively. Analyses were performed on the total anxiety (GAD, SAD and PD) and GAD groups. Results: During 1 year of treatment with pregabalin, dizziness (12.5%) was the only treatment-related adverse event (AE) occurring >= 10%. Somnolence, weight gain, headache and insomnia occurred at 7.6%, 5.5%, 5.3% and 4.7%, respectively. Few treatment-related AEs were rated as severe in the total anxiety (5.1%) or GAD (3.6%) groups. Discontinuation rates due to AEs were similar (9.7% and 10.6%, respectively). No clinically significant laboratory, electrocardiogram, or other treatment-related safety findings were noted, except for treatment-related weight gain, which occurred in both the total (24.4%) and GAD (19.4%) groups. Mean CGI-S scores were similar at baseline in the total (n=528; score, 3.4) and GAD groups (n=330; score, 3.6), and CGI-S responder rates were similar at last-observation-carried-forward endpoint (51.3% and 48.1%, respectively). Conclusions: Pregabalin was generally well tolerated in the long-term treatment of anxiety disorders. Improvement in illness severity was maintained over time. The key limitations of this study were that it was not randomized and neither placebo- nor active-comparator-controlled.