October 20th 2003
By Paula Moyer
MIAMI BEACH, FL -- October 20, 2003 -- Among the once-daily therapies for attention deficit/hyperactivity disorder (ADHD), conventional stimulants may be more effective than atomoxetine (Strattera), investigators reported here October 15th at the 50th Anniversary Meeting of the American Academy of Child and Adolescent Psychiatry.
"We examined the different treatments' effect size as a way to compare responses," said lead investigator Kenneth W. Steinhoff, MD, associate clinical professor, University of California-Irvine, who said he declined any pharmaceutical funding for the study. "We compared the data in large placebo-controlled studies that the different companies had submitted to the [Food and Drug Administration] as their Phase III registration trials."
The three drugs studied were osmotic release oral system (OROS) methylphenidate (Concerta), mixed amphetamine salts (Adderall XR), and once-daily atomoxetine (Strattera).
The studies involved a combined database of 637 participants, 45.5% of whom received treatment, with 95 receiving OROS methylphenidate, 112 receiving mixed amphetamine salts, and 83 receiving atomoxetine. Of the remaining 347 placebo participants, 90 were in the OROS methylphenidate trial, 173 in the mixed amphetamine salts trial, and 84 in the atomoxetine trial.
The instruments used for evaluating effect were the Likert scale changes and the effect size, based on baseline standard deviation. The investigators also compared teacher and parent evaluations.
The Likert scale difference on the parent evaluations was 0.76 for OROS, 0.51 for mixed amphetamines, and 0.17 for atomoxetine. On the teacher evaluations, the Likert scale difference was 0.75 for OROS, 0.52 for mixed amphetamines, and 0.13 for atomoxetine.
The standard deviations from baseline for the parent evaluations were 1.02 for OROS, 0.74 for mixed amphetamines, and 0.62 for atomoxetine. For the teacher evaluations, these parameters were 0.96 for OROS, 0.84 for mixed amphetamines, and 0.44 for atomoxetine.
"The teachers do not see the effect size that the parents see," Dr. Steinhoff said. Although it was beyond the scope of the study, he said that much ADHD symptomatology is experienced on the home front with homework, bedtime preparations, and getting ready for school in the morning.
"Our findings show that, among once-daily formulations, the treatments that are most likely to be effective are the stimulants," he said. "Atomoxetine may be doing something that teachers don't see, but that parents do."
[Study title: A Single Daily Dose ADHD Medication Treatment Effect Size Evaluation. Abstract A4]