What is the recommended dosing for atomoxetine (Strattera) in adult Attention Deficit Hyperactivity Disorder (ADHD)?

Atomoxetine Dosing for Adult ADHD

For adults with ADHD, start atomoxetine at 40 mg once daily, then increase after 7-14 days to a target dose of 80 mg/day, with a maximum of 100 mg/day or 1.4 mg/kg/day (whichever is lower). 1, 2

Initial Dosing Strategy

• Begin with 40 mg orally once daily in the morning for the first 7-14 days 1, 2
• This starting dose allows assessment of tolerability before escalating to therapeutic levels 3, 4

Titration Schedule

• Increase to 60 mg/day after the first week, then to the target dose of 80 mg/day after another 7-14 days 1
• The dose is typically adjusted every 7-14 days based on clinical response and tolerability 1, 2
• Maximum dose is 100 mg/day or 1.4 mg/kg/day, whichever is lower 1, 2, 5

Dosing Flexibility

• Atomoxetine can be administered as a single daily dose (morning or evening) or split into two evenly divided doses to reduce side effects 2, 3, 4
• Split dosing may improve tolerability, particularly for gastrointestinal side effects like nausea 2

Critical Timing Considerations

• Allow 6-12 weeks at target dose before judging efficacy, as atomoxetine has a delayed onset of therapeutic effect compared to stimulants 2, 6
• This delayed response is a common pitfall—premature discontinuation due to perceived lack of efficacy is a frequent clinical error 6

Real-World Dosing Problem

• Underdosing is extremely common in clinical practice, with real-world data showing average doses around 60 mg/day despite the 80 mg/day target recommendation 6
• This suboptimal dosing is associated with poor patient outcomes and inadequate symptom control 6
• Maintain patients at the target dose of 80 mg/day for 4-6 weeks minimum before considering the trial unsuccessful 6

Monitoring Requirements

• Monitor blood pressure and heart rate at baseline and during treatment, as modest increases occur but are generally well tolerated 2, 3, 4
• Screen for suicidal ideation, particularly in the first few months of treatment or with dose changes, per FDA black box warning 2
• Systematically assess for common side effects: decreased appetite, nausea, dry mouth, insomnia, constipation, dizziness, sweating, dysuria, and sexual dysfunction 3, 4

Clinical Trial Evidence

• In two large 10-week trials, atomoxetine at 60-120 mg/day produced mean reductions in ADHD symptom scores of 28-30% versus 18-20% with placebo 3, 4
• Efficacy was maintained in a 34-week extension phase 3, 4
• Japanese adult studies confirmed tolerability up to 120 mg/day maximum dose 7

Special Populations

• No dose adjustment needed for renal insufficiency, including end-stage renal disease 5
• Consider dose adjustments for CYP2D6 poor metabolizers or patients taking CYP2D6 inhibitors 2

Positioning in Treatment Algorithm

• Atomoxetine is second-line therapy for adult ADHD—stimulants (methylphenidate or amphetamines) remain first-line due to larger effect sizes 2
• Consider atomoxetine as first-line in specific situations: comorbid substance use disorders, patient preference to avoid controlled substances, or comorbid tic disorders 2, 3, 4
• The lack of abuse potential and non-controlled status makes atomoxetine particularly valuable for patients with substance abuse history 3, 4

Common Pitfalls to Avoid

• Starting at too high a dose (>40 mg/day) increases side effects and early discontinuation 2
• Judging efficacy before 6-12 weeks at target dose leads to premature treatment abandonment 2, 6
• Settling for subtherapeutic doses (60 mg/day) rather than pushing to the 80 mg/day target 6
• Failing to set patient expectations about delayed onset compared to stimulants 6