• Observed and change from baseline measures for ADHD-RS total scores will be summarized by descriptive statistics and analyzed by repeated measures of analysis of covariance.
  

• CGI-I and each PSQ item separately were summarized by descriptive statistics and frequency distributions. Treatment effects were tested by chi-square statistics. Onset of effect was assessed by PSQ on Days 2 to 13.
  

Methylphenidate and atomoxetine are available for the treatment of ADHD in children. Methylphenidate is thought to block the reuptake of norepinephrine and dopamine into the presynaptic neuron and increase the release of these monamines into the extraneuronal space. The mechanism by which atomoxetine produces its therapeutic effect is thought to be related to selective inhibition of the presynaptic norephinephrine transporter. This was a multi-center, randomized, open-labeled, parallel design study of extended-release methylphenidate and atomoxetine in children aged 6 to 12 years with ADHD as evaluated by physicians and parents. Children were randomly assigned (2:1, respectively) to 3 weeks of treatment with extended-release methylphenidate or atomoxetine. Physicians evaluated treatment using the ADHD Rating Scale (ADHD-RS) and the Clinical Global Impression-Improvement of Illness scale (CGI-I). Assessments were made prior to beginning treatment (screening), at a telephone interview 1 week after beginning treatment, at a clinic visit 2 weeks after beginning treatment, and at the final clinic visit (3 weeks). Parents assessed treatment using the Parent Satisfaction Questionnaire (PSQ) from treatment days 2 to 13 and at the clinical visit 3 weeks after beginning treatment. The questions of interest included whether there is a difference between treatment in the improvement of behavior and the timing of such differences. Vital signs, height, and weight were also recorded as were adverse events.

Study drug was to be taken orally once each day. Patients randomly assigned to extended-release methylphenidate began treatment with 18 mg/day. Patients randomly assigned to atomoxetine began treatment with 0.5 mg/kg/day. The study medication was to be titrated as considered appropriate by the patient's physician. The duration of treatment was 21 days.