Long-Term, Open-Label Extension Study of Guanfacine Extended Release in Children and Adolescents with ADHD

Introduction: Guanfacine is a noradrenergic agonist that is believed to improve symptoms of attention-deficit/hyperactivity disorder (ADHD) through selective actions at alpha(2A)-adrenoceptors in the prefrontal cortex. A recent double-blind, multicenter trial supports the efficacy and safety of guanfacine extended release (GXR) for pediatric ADHD. This long-term, open-label extension was conducted to study the safety profile and effectiveness of GXR for up to 2 years. Methods: Subjects were 240 children 6-17 years of age with a diagnosis of ADHD who participated in the preceding randomized trial. GXR was initiated at 2 mg/day and titrated as needed in 1-mg increments to a maximum of 4 mg/day to achieve optimal clinical response. Results: The most common adverse events were somnolence (30.4%), headache (26.3%), fatigue (14.2%), and sedation (13.3%). Somnolence, sedation, and fatigue were usually transient. Cardiovascular-related adverse events were uncommon, although small reductions in mean blood pressure and pulse rate were evident at monthly visits. ADHD Rating Scale, Version IV, total and sub-scale scores improved significantly from baseline to endpoint for all dose groups (P<.001 for all comparisons, intent-to-treat population). Conclusion: Long-term treatment with GXR was generally safe for up to 24 months of treatment, and effectiveness was maintained over this treatment period.