Long-Term Treatment with Atomoxetine for Attention-Deficit/Hyperactivity Disorder Symptoms in Children and Adolescents with Autism Spectrum Disorder: An Open-Label Extension Study

Objective: The efficacy and tolerability of long-term treatment with atomoxetine for symptoms of attention-deficit/hyperactivity disorder (ADHD) in children with autism spectrum disorder (ASD) has not been established. Methods: In this study, 88 patients 6-17 years of age, with ADHD and ASD, were treated with 1.2 mg/kg/day atomoxetine for 20 weeks as follow-up of an 8 week double-blind placebo-controlled period. Primary endpoint was the ADHD Rating Scale (ADHD-RS). Results: After 8 weeks of initial treatment, the mean total, inattention, and hyperactivity-impulsivity ADHD-RS further decreased significantly from 34.9 to 27.0 for the total ADHD-RS, from 18.3 to 14.5 for the ADHD-RS inattention subscale, and from 16.5 to 12.6 for the hyperactivity-impulsivity subscale. Adverse events were mild and tended to diminish over time during continued treatment, especially regarding nausea and fatigue. There were no serious adverse events. Conclusions: The results of the present analysis suggest that continued treatment with atomoxetine up to 28 weeks further improve ADHD symptoms in children and adolescents with ASD, while adverse events tend to subside. Future studies investigating the long-term efficacy of atomoxetine in children and adolescents with ASD should be randomized and placebo controlled. This study has been registered in ClinicalTrials.gov (www.clinicaltrials.gov) under registration number NCT00380692.