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

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

Disclosures

Pharmacotherapy. 2004;24(8) 

In This Article

Dosing and Administration

Atomoxetine is indicated for the long-term treatment of ADHD in children, adolescents, and adults. Some advantages for the use of atomoxetine over stimulants are that atomoxetine may be given without regard to meals and does not need to be tapered on discontinuation. Based on pediatric pharmacokinetic data, atomoxetine may be dosed on a milligram/kilogram basis in pediatric patients owing to its proportionality of dose-to-plasma concentration effect. For children weighing less than 70 kg, initial dosages should be 0.5 mg/kg/day. Atomoxetine may be given either as a single dose or in divided doses because of the drug's rapid absorption and elimination, which result in steady-state profiles that are similar to single-dose profiles. Dosages should be titrated after 3 days of initial therapy to a target daily dose of approximately 1.2 mg/kg. The maximum recommended daily dose in children is 1.4 mg/kg or 100 mg, whichever is less, owing to the lack of significance in producing a greater reduction of symptoms for dosages greater 1.4 mg/kg/day. For patients who are treated concomitantly with a strong CYP2D6 inhibitor (e.g., paroxetine, fluoxetine, quinidine), atomoxetine should be started at 0.5 mg/kg/day and cautiously increased to a maximum dosage of 1.2 mg/kg/day if after 4 weeks of therapy the patient does not improve clinically. In studies to evaluate atomoxetine in children, efficacy was not assessed in those weighing less than 25 kg; therefore, caution should be exercised when beginning therapy, and patients should be monitored closely for adverse events during titration.

For children, adolescents, and adults weighing more than 70 kg, the initial dosage should be at 40 mg/day either in divided doses or as a single daily dose in the morning. Titration should occur after 3 days of therapy to a target dosage of 80 mg/day. Like antidepressants, the full benefit of atomoxetine may not be seen until about the fourth week of therapy. Dosages may be further titrated if clinical efficacy is not achieved, to a maximum dosage of 100 mg/day. If the use of a strong CYP2D6 inhibitor (e.g., paroxetine, fluoxetine, quinidine) is in place, atomoxetine should be started at 40 mg/day and cautiously increased to a maximum dosage of 80 mg/day if the patient does not exhibit a clinical response after 4 weeks of therapy. Doses greater than 120 mg or total daily doses above 150 mg have not been formally evaluated for safety. Patients should be assessed periodically for the continued maintenance of ADHD symptoms if atomoxetine is to be used long term. Discontinuation of atomoxetine may occur at any time throughout therapy without tapering.[16]

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