Strattera Starting Dose
For children and adolescents weighing ≤70 kg, start Strattera at approximately 0.5 mg/kg/day for the first 3 days, then increase to a target dose of 1.2 mg/kg/day; for those >70 kg and adults, start at 40 mg/day and increase after a minimum of 3 days to a target of 80 mg/day. 1
Weight-Based Dosing Algorithm
Children and Adolescents (≤70 kg):
- Initial dose: 0.5 mg/kg/day (can be given as single morning dose or divided twice daily)
- Target dose: 1.2 mg/kg/day after minimum 3 days
- Maximum dose: 1.4 mg/kg/day or 100 mg/day, whichever is lower 1
Children/Adolescents (>70 kg) and Adults:
- Initial dose: 40 mg/day
- Target dose: 80 mg/day after minimum 3 days
- Maximum dose: 100 mg/day 1
Dosing Schedule Options
Atomoxetine can be administered either:
- Once daily in the morning (shown effective in clinical trials) 2
- Divided twice daily (early morning and late afternoon/early evening) 2
Both regimens demonstrate equivalent efficacy, allowing flexibility based on tolerability and patient preference.
Critical Titration Considerations
Do not rush the titration. The evidence shows that reaching target dose quickly without adequate time for assessment leads to suboptimal outcomes. After reaching 1.2 mg/kg/day (or 80 mg/day in adults), maintain this dose for 4-6 weeks before judging efficacy 3. Many clinicians undertitrate atomoxetine in real-world practice (averaging only 60 mg/day in adults versus the 80 mg/day target), which contributes to treatment failure 3.
If inadequate response occurs after 4-6 weeks at target dose, you may increase to the maximum of 1.4 mg/kg/day or 100 mg/day 1. However, clinical trials showed that 1.8 mg/kg/day provided no additional benefit over 1.2 mg/kg/day, suggesting the standard target is optimal for most patients 2.
Special Populations Requiring Dose Adjustment
Hepatic Impairment:
- Moderate hepatic insufficiency (Child-Pugh Class B): Reduce to 50% of normal dose
- Severe hepatic insufficiency (Child-Pugh Class C): Reduce to 25% of normal dose 4
CYP2D6 Poor Metabolizers:
Approximately 7% of the population are CYP2D6 poor metabolizers with significantly higher plasma levels 1. While formal dose adjustments aren't mandated, consider slower titration and lower maintenance doses if genetic testing reveals poor metabolizer status, as these patients experience 10-fold higher drug exposure 5, 6.
Concomitant CYP2D6 Inhibitors:
When co-administering strong CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine), initiate at the standard dose but titrate more cautiously and consider maintaining at lower doses, as these medications can convert extensive metabolizers into functional poor metabolizers 1.
Common Pitfalls to Avoid
Stopping too early: The most critical error is discontinuing atomoxetine before 4-6 weeks at target dose. Unlike stimulants with immediate effects, atomoxetine requires sustained exposure at therapeutic levels 3, 7. One study showed progressive improvement from week 6 to week 12, with between-group differences continuing to increase over time 7.
Undertitration: Real-world data consistently shows clinicians using subtherapeutic doses. The 1.2 mg/kg/day target (or 80 mg/day in adults) is evidence-based from dose-response studies showing this dose provides optimal efficacy 2.
Rapid titration causing intolerance: Increasing dose too quickly, particularly in the first week, increases gastrointestinal side effects (nausea, vomiting) and somnolence, leading to unnecessary discontinuation 1. The initial 0.5 mg/kg/day for 3 days allows tolerance to develop.
Safety Monitoring Requirements
Before initiating treatment, obtain:
- Personal and family cardiac history (sudden death, arrhythmias, long QT syndrome, cardiomyopathy)
- Baseline blood pressure and heart rate
- Height and weight 8
During treatment, monitor closely for:
- Suicidal ideation (black box warning): Particularly critical during first few months and at dose changes in children/adolescents 1
- Cardiovascular parameters: Atomoxetine causes mild increases in heart rate and blood pressure 8
- Growth parameters: Monitor height/weight as atomoxetine may cause transient growth delays 8
- Hepatic function: Rare cases of hepatitis reported; discontinue if jaundice or laboratory evidence of liver injury develops 8
The evidence consistently supports this weight-based, gradual titration approach as providing the optimal balance between efficacy and tolerability while minimizing the risk of premature discontinuation due to adverse effects.