Strattera (Atomoxetine) Dosing
For children and adolescents up to 70 kg, start Strattera at 0.5 mg/kg/day and increase after a minimum of 3 days to a target dose of 1.2 mg/kg/day, with a maximum of 1.4 mg/kg/day or 100 mg (whichever is less); for children and adolescents over 70 kg and adults, start at 40 mg/day and increase after a minimum of 3 days to a target of 80 mg/day, with a maximum of 100 mg/day. 1
Weight-Based Dosing Algorithm
Children and Adolescents ≤70 kg
- Starting dose: 0.5 mg/kg/day
- Titration: Wait minimum 3 days before increasing
- Target dose: 1.2 mg/kg/day (this is the therapeutic goal)
- Maximum dose: 1.4 mg/kg/day or 100 mg/day, whichever is less
- Administration: Can be given as single morning dose OR divided into morning and late afternoon/early evening doses 1
Children and Adolescents >70 kg and Adults
- Starting dose: 40 mg/day
- Titration: Wait minimum 3 days before increasing
- Target dose: 80 mg/day (this is the therapeutic goal)
- Optional increase: After 2-4 additional weeks at 80 mg, may increase to 100 mg if response is suboptimal
- Maximum dose: 100 mg/day
- Administration: Single morning dose OR divided doses (morning and late afternoon/early evening) 1
Critical Titration Considerations
The evidence strongly supports slower titration to minimize adverse events. A study comparing fast versus slow titration found that patients titrated to 1.2 mg/kg/day over 3 days (fast/once daily) had significantly higher rates of decreased appetite (14.3% vs 8.0%) and somnolence (14.3% vs 4.2%) in the first 2 weeks compared to those titrated over at least 2 weeks with twice-daily dosing 2. Therefore, consider twice-daily dosing and slower titration over the first 1-2 weeks to improve tolerability, particularly in treatment-naive patients.
Dosing Adjustments for Specific Populations
Hepatic Impairment
- Moderate hepatic impairment (Child-Pugh Class B): Reduce initial and target doses to 50% of normal
- Severe hepatic impairment (Child-Pugh Class C): Reduce initial and target doses to 25% of normal 1
CYP2D6 Poor Metabolizers or Strong CYP2D6 Inhibitor Use
When using strong CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine) or in known CYP2D6 poor metabolizers:
- Children/adolescents ≤70 kg: Start at 0.5 mg/kg/day, increase to usual target of 1.2 mg/kg/day ONLY if symptoms fail to improve after 4 weeks AND initial dose is well tolerated
- Children/adolescents >70 kg and adults: Start at 40 mg/day, increase to usual target of 80 mg/day ONLY if symptoms fail to improve after 4 weeks AND initial dose is well tolerated 1
This adjustment is critical because approximately 7% of the population are poor metabolizers with significantly higher plasma levels and longer half-lives, leading to increased adverse effects 3.
Maintenance Treatment
The benefit of maintaining treatment has been demonstrated in controlled trials. Patients who achieved response at doses of 1.2-1.8 mg/kg/day showed continued benefit when maintained on the same dose 3, 1. Periodic reassessment is recommended to determine continued need for treatment, but Strattera can be discontinued without tapering 1.
Common Pitfalls to Avoid
Underdosing is Prevalent and Problematic
Real-world data reveal that only 45% of adult monotherapy patients and 26.7% of all adult patients reach the recommended 80 mg/day target dose 4, 5. This is a critical error. Adults who reached ≥80 mg/day had 159.3 days of therapy versus only 65.6 days for those dosed <80 mg—a difference of 93.8 days 4. The average real-world dose is approximately 60 mg/day, which is suboptimal 6, 5.
Inadequate Duration at Target Dose
Patients must remain at target dose for 4-6 weeks before judging efficacy 6. Premature discontinuation due to perceived lack of response when the patient hasn't been at adequate dose for adequate duration is a common mistake.
Titrating Too Quickly
As noted above, rapid titration (reaching 1.2 mg/kg/day in 3 days) significantly increases early adverse events, particularly somnolence and decreased appetite 2. While the FDA label allows this rapid titration, clinical practice may benefit from slower approaches.
Safety Monitoring
Black Box Warning
Monitor closely for suicidal ideation, clinical worsening, and unusual behavioral changes, especially during the first few months or at dose changes 3, 1. This warning applies to children and adolescents; analyses in adults did not show increased suicidal ideation 3.
Cardiovascular Monitoring
- Obtain personal and family cardiac history before initiating
- Monitor blood pressure and heart rate
- Consider ECG if risk factors present
- Most common cardiovascular effects: increased heart rate and blood pressure 7
Other Monitoring
- Hepatic function: Discontinue if jaundice or laboratory evidence of liver injury develops 1
- Growth parameters: Monitor height and weight in pediatric patients 3, 1
- Urinary symptoms: Monitor for urinary hesitancy/retention 1