Long-term, open-label extension study of guanfacine extended release in children and adolescents with ADHD

Guanfacine is a noradrenergic agonist that is believed to improve symptoms of attention-deficit/hyperactivity disorder (ADHD) through selective actions at alpha2A-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.

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.

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 subscale scores improved significantly from baseline to endpoint for all dose groups (P<.001 for all comparisons, intent-to-treat population).

Long-term treatment with GXR was generally safe for up to 24 months of treatment, and effectiveness was maintained over this treatment period.