The study was conducted in Mexico, China, and Korea, and randomized 164 children to atomoxetine and 166 to methylphenidate. Response was defined as 40% or greater reduction in total score on the Attention-Deficit Hyperactivity Disorder Rating Scale IV - Parent Version: Investigator Administered and Scored (ADHDRS-IV-Parent:Inv) scale.

Presenter Yueng Wang, MD, professor, Institute of Mental Health, Beijing Medical University, Beijing, China, said results show a similar response rate for the 2 treatments (77.4% for atomoxetine and 81.5% for methylphenidate; no statistical significant difference, P = .404).

From a baseline score of 38.6 in the atomoxetine group and 37.4 in the methylphenidate group, by the fifth weekly clinic visit, the researchers observed a mean 15-point improvement, with an improvement of more than 20 points after 8 weeks of treatment.

Both treatments reduced inattention and hyperactivity/impulsivity aspects of ADHD as measured. Methylphenidate's effect on the inattention subscale of ADHDRS-IV-Parent:Inv approached statistical superiority over atomoxetine (P = .054)

Similarly both treatments resulted in a drop of about 11 points from a baseline of about 26 on Conners' Parent Rating Scale-Revised: Short Form (CPRS-R:S).

From a baseline of 5.3, there was a drop of about 2 points for both treatments on another rating scale, the Clinical Global Impressions Severity-Attention-Deficit/Hyperactivity Disorder (CGI-ADHD-S) score, with no difference between the treatments (P = .154).

Most of the patients (more than 80%) were younger than 12 years, and a similar proportion were boys.

There were more adverse events in the atomoxetine group than in the methylphenidate group (86.6% vs 67.5%, P < .01). Eighteen patients in the atomoxetine group (11%) and 6 (3.6%) in the methylphenidate group dropped out of the study because of adverse events. There was 1 serious adverse event, a focal motor convulsion, in an atomoxetine-treated patient.

There was significantly more anorexia, somnolence, dizziness, and vomiting in the atomoxetine treated group compared with those on methylphenidate. None of the common adverse events were significantly more common in the methylphenidate-treated patients.

There was a slight weight loss of 1.2 kg in the atomoxetine-treated patients compared with a loss of 0.4 kg in those treated with methylphenidate, a significant difference (P < .001).

However the researchers say most adverse events were mild to moderate in severity, occurred earlier in the study, and tended to decline over time.

They suggest that the lower than expected rate of adverse events in the methylphenidate group may be explained by the dose, 0.2 to 0.6 mg twice a day, which was lower than that used in previous studies.


[Presentation title: Atomoxetine vs, Methylphenidate in ADHD Treatment: an International Pediatric Trial.]

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