Atomoxetine, a Novel Treatment for Attention-Deficit-Hyperactivity Disorder

Alisa K. Christman, Pharm.D.; Joli D. Fermo, Pharm.D.; John S. Markowitz, Pharm.D.


Pharmacotherapy. 2004;24(8) 

In This Article

Adverse Effects

A total of 2067 pediatric patients and 267 adult patients treated with atomoxetine or placebo in clinical trials were evaluated for adverse effects occurring with the agent. Throughout the trials, no deaths were reported as a result of treatment with atomoxetine, and discontinuation rates as a result of adverse effects were low. In the 2067 children and adolescents treated with either placebo or atomoxetine, the most commonly occurring adverse events were gastrointestinal (e.g., dyspepsia, nausea, vomiting, abdominal pain, decreased appetite) and central nervous system effects (e.g., fatigue, dizziness, mood swings, headache, insomnia). Weight loss also occurred as a result of decreased appetite; however, few trials reported this as an adverse event.[34] The adverse-event rates in the trials were similar for both the once-daily and twice-daily dosing regimens.[16,34]

Overall, the tolerability of atomoxetine in clinical trials has been favorable, with most events occurring and dissipating throughout therapy. The most commonly occurring adverse events observed in short-term (< 9 wks) clinical trials evaluating both once- and twice-daily dosing in pediatric patients were gastrointestinal and central nervous system effects. These events occurred at a rate greater than 5% for both once- and twice-daily dosing of atomoxetine versus placebo.[16] No significant differences were seen in the relationship between the dose of atomoxetine and the adverse event.

The rate of discontinuation was 3.5% in patients treated with atomoxetine and 1.4% for the placebo groups in the placebo-controlled trials.[16] In most studies evaluating atomoxetine's effects in poor and extensive metabolizers, the rate of discontinuation due to adverse effects was approximately 5% for extensive metabolizers and 7% for poor metabolizers.[16] Occurrence of adverse events appears to be dose dependent, with a higher percentage of discontinuations at dosages of atomoxetine greater than 1.5 mg/kg/day.[16]

In clinical trials involving adults, the emergence of clinically significant, intolerable adverse events was low. The most commonly observed adverse events were dry mouth, insomnia, nausea, decreased appetite, constipation, urinary retention or difficulties with micturition, erectile disturbance, dysmenorrhea, dizziness, and decreased libido. Sexual dysfunction occurred in about 2% of patients treated with atomoxetine.[16] The most commonly reported events were erectile disturbance, impotence, and abnormal orgasms. The rate of discontinuation was 8.5% for atomoxetine-treated patients and 3.4% for placebo-treated patients.[16]