Prospective, naturalistic, pilot study of open-label atomoxetine treatment in preschool children with attention-deficit/hyperactivity disorder

Objective: The aim of this study was to report preliminary data regarding effectiveness and tolerability of atomoxetine in 3- to 5-year-old preschool children with attention-deficit/hyperactivity disorder (ADHD). Methods: Nine boys and 3 girls (mean age=5.0±0.72 years) diagnosed with ADHD were treated with atomoxetine in an open-label pilot study. Atomoxetine was gradually titrated to a maximum dose of 1.8mg/kg per day. Results: There was a significant effect of time from baseline to end point on the parent-rated hyperactivity/impulsivity Swanson Nolan and Pelham (SNAP-IV-HI) subscale ratings (F[9, 11]=6.32, p<0.0001). The mean difference between the baseline and end-point parent SNAP-IV-HI scores was 10.2±7.3 (p=0.0005). The rate of positive response (defined as at least a 30% reduction in the end-point parent SNAP-IV-HI scores and a Clinical Global Impressions-Improvement [CGI-I] rating of Much Improved or Very Much Improved) was 75%. The Children's Global Assessment Scale scores improved significantly over time [F(9, 11)=6.24 p<0.001]. The mean end-point daily dose of atomoxetine was 1.59±0.3mg/kg. A high proportion (66.7%) of the preschoolers experienced side effects with atomoxetine. Side effects of defiance, tantrums, aggression, and irritability were most disconcerting to parents, and gastrointestinal complaints were the most commonly reported adverse effects. One child was terminated from the study due to "chest ache." There were no changes in weight, height, or cardiovascular measures. Conclusion: This open-label pilot study provides preliminary evidence of effectiveness and tolerability of atomoxetine for treating ADHD in preschool children, although double-blind, randomized, placebo-controlled studies are needed to confirm this.