Response/Remission With Guanfacine Extended-Release and Psychostimulants in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder

Objective: In this post hoc analysis, we assessed whether guanfacine extended-release (GXR) adjunctive to a psychostimulant resulted in greater response and remission rates than placebo + psychostimulant in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Method: In this 9-week, double-blind, placebo-controlled dose-optimization study, participants (N = 461) aged 6 to 17 years with suboptimal response to psychostimulants were randomized to GXR on awakening (AM) + psychostimulant, GXR at bedtime (PM) + psychostimulant, or placebo + psychostimulant. Results: At the final on-treatment assessment, more participants in both GXR + psychostimulant groups versus the placebo + psychostimulant group achieved response as assessed by 2 criteria: reduction from baseline in ADHD Rating Scale IV (ADHD-RS-IV) total score (1) >= 40% (GXR AM + psychostimulant = 69.8%, GXR PM + psychostimulant = 70.3%, versus placebo + psychostimulant = 57.9%; p = .032 and p = .026, respectively), or (2) >= 50% (63.1%, 64.9%, versus 43.4%; p < .001 for both). Results were similar for symptomatic remission (ADHD-RS-IV total score <= 18; 61.1%, 62.2%, versus 46.1%; p = .010 and p = .005, respectively) and syndromal remission (symptomatic remission plus Clinical Global Impressions of Severity of Illness score <= 2). The most common treatment-emergent adverse events in participants receiving GXR + psychostimulant were headache (21.2%) and somnolence (13.6%). Conclusion: GXR + psychostimulant treatment resulted in a greater percentage of participants meeting stringent criteria for response and remission compared with placebo + psychostimulant. The adverse event profile of adjunctive therapy was consistent with known effects of either treatment alone. Clinical trial registration information-Efficacy and Safety of SPD503 in Combination With Psychostimulants; http://clinicaltrials.gov/; NCT00734578.