What is the recommended dosage of atomoxetine (Strattera) for attention deficit hyperactivity disorder (ADHD)?

Atomoxetine Dosage for ADHD

Atomoxetine should be initiated at 40 mg daily and titrated to a maximum dose of 1.4 mg/kg/day or 100 mg/day (whichever is lower), using a sequential weight-based approach. 1

Dosing Algorithm

Initial Dosing

• Starting dose: 40 mg orally once daily 1
• Can be administered as a single morning dose or divided into two doses (early morning and late afternoon/early evening) 1, 2

Titration Schedule

• Adjust dose every 7-14 days based on clinical response and tolerability 1
• Standard titration sequence: 40 mg → 60 mg → 80 mg daily 1
• Target dose: 1.2 mg/kg/day for most patients, as this dose demonstrates equivalent efficacy to higher doses without additional benefit 1, 3

Maximum Dosing

• Maximum recommended dose: 1.4 mg/kg/day OR 100 mg/day, whichever is lower 1
• The 1.8 mg/kg/day dose provides no additional benefit over 1.2 mg/kg/day 2, 3
• Doses of 0.5 mg/kg/day show intermediate efficacy between placebo and therapeutic doses 3

Critical Safety Considerations

Black Box Warning

• Monitor closely for suicidal ideation, clinical worsening, and unusual behavioral changes, especially during the first few months of treatment or at dose changes 1
• This warning applies specifically to children and adolescents based on analysis of 12 placebo-controlled trials; similar findings were not observed in adult trials 1

Cardiovascular Monitoring

• Obtain cardiac history before initiating treatment: assess for sudden death, cardiovascular symptoms, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, and long QT syndrome 1
• Monitor heart rate and blood pressure as atomoxetine may increase both parameters 1
• Consider ECG if cardiac risk factors are present 1

Drug Interactions

• CYP2D6 metabolism: Atomoxetine is primarily metabolized through CYP2D6 1
• SSRIs can elevate serum atomoxetine levels—dose adjustment may be necessary 1
• Approximately 7% of the population are poor metabolizers with significantly higher plasma levels and longer half-lives, leading to increased adverse effects 1

Common Adverse Effects

The most frequently reported adverse effects include nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence 1. Initial somnolence and gastrointestinal symptoms are particularly common if dosage is increased too rapidly 1. Growth delays may occur in the first 1-2 years of treatment, with return to expected measurements after 2-3 years 1.

Special Populations

Pregnancy and Breastfeeding

• Caution advised during breastfeeding: No published studies exist, but based on pharmacokinetic properties (low molecular weight, long half-life), atomoxetine will likely be present in human milk 1
• No increased risk for major congenital malformations or long-term neurodevelopmental outcomes in pregnancy 1

Cognitive Impairment

• Lower IQ (<85) is associated with decreased clinical response to atomoxetine 4
• Response rates: 20.7% in patients with IQ <85 versus 76.9% in patients with IQ ≥85 4

Administration Flexibility

• Once-daily morning dosing is effective and may improve adherence 2
• Divided dosing (morning and late afternoon) is an alternative option 1, 2
• Available formulations: capsules (10,18,25,40,60,80,100 mg) and oral solution (4 mg/mL) 1