Once-Daily Atomoxetine Effective in ADHD

Laurie Barclay, MD

November 26, 2002

Nov. 27, 2002 — Once-daily atomoxetine (Strattera) is effective for children and adolescents with attention deficit hyperactivity disorder (ADHD), according to the results of a randomized, placebo-controlled trial reported in the November issue of the American Journal of Psychiatry. The effect was similar to that reported previously for twice-daily dosing.

The U.S. Food and Drug Administration approved atomoxetine yesterday for the treatment of ADHD in children, adolescents, and adults.

"Perhaps the most striking finding of this study is the evidence that despite the relatively short plasma half-life of atomoxetine (about four hours for most patients), once-daily dosing in the morning was associated with effects that persisted into the evening," write David Michelson, MD, from Lilly Research Laboratories in Indianapolis, Indiana, and colleagues. "This observation suggests that factors other than time on receptor could be important determinants of response or that pharmacokinetics in the central nervous system differ from those in the plasma."

In this double-blind study, 171 children and adolescents with ADHD, aged 6 to 16 years, received six weeks of treatment with either once-daily atomoxetine or placebo. Investigator, parent, and teacher ratings showed better outcomes in the atomoxetine group compared with the placebo group. The treatment effect size (0.71) was similar to those reported in previous studies of twice-daily atomoxetine dosing. Study discontinuation because of adverse events was less than 3% for both treatment groups, and no serious safety concerns were reported.

Although ratings in parent diaries suggested that drug-specific effects were sustained late in the day, the authors note that the results must be interpreted cautiously because the instrument is new and its psychometric characteristics and replicability require further study.

Other limitations of this study include lack of a twice-daily dosing arm, preventing definitive determination of the relative efficacy of once- versus twice-daily atomoxetine administration. However, the treatment effect size in this study for the primary outcome measure was similar to those reported in earlier studies of atomoxetine given twice daily and of methylphenidate. This study also did not address optimal dosing for once-daily administration or long-term outcomes.

"These reservations notwithstanding, the results of this study confirm and extend the results of previous studies," the authors write. "Patients often prefer once-daily dosing to more frequent regimens because of its convenience, and the data presented here suggest that for many patients with ADHD, treatment with once-daily atomoxetine will be a viable option."

Eli Lilly and Company funded this study and employs its lead author.

Am J Psychiatry. 2002;159:1896-1901

Reviewed by Gary D. Vogin, MD

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