Efficacy of Guanfacine Extended Release in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder and Comorbid Oppositional Defiant Disorder.

Objective: To assess the efficacy of the non-stimulant guanfacine extended release (GXR) on attention-deficit/hyperactivity disorder (ADHD) symptoms in children and adolescents, with and without comorbid oppositional defiant disorder (ODD). Methods: Data were derived from 4 phase 3, randomized, placebo-controlled trials of dose-optimized GXR monotherapy, in which at least 10% of participants had a diagnosis of comorbid ODD. SPD503-312 and SPD503-316 were 10- to 13-week studies of GXR (1-7 mg/d). SPD503-314 and SPD503-307 were 8-week studies of GXR (1-4 mg/d). Efficacy was assessed using the ADHD Rating Scale IV (ADHD-RS-IV) total scores. Results: In total, 1,084 participants were included (SPD503-312 and SPD503-316, n = 537; SPD503-314, n = 333; and SPD503-307, n = 214). GXR was associated with significant improvements in ADHD core symptoms at endpoint in participants with and without ODD (p< 0.01 in all studies). Placebo-adjusted least-squares mean (95% confidence interval) changes from baseline to endpoint in the ADHD-RS-IV total scores in participants with and without ODD were -8.6 (-14.4, -2.8) and -7.3 (-9.5, -5.0) in the pooled data from SPD503-312 and SPD503-316, -12.6 (-19.6, -5.7) and -8.7 (-11.8, -5.5) in SPD503-314, and -12.7 (-17.3, -8.1) and -11.8 (-19.3, -4.4) in SPD503-307, respectively. The corresponding effect sizes were 0.688 and 0.598 in SPD503-312 and SPD503-316, 0.876 and 0.729 in SPD503-314, and 0.962 and 0.842 in SPD503-307. Conclusion: The findings demonstrate the efficacy of GXR for treating ADHD in children and adolescents with comorbid ODD.