Atomoxetine Dose Titration Schedule
Initial Dosing Strategy
For children and adolescents weighing ≤70 kg, start atomoxetine at 0.5 mg/kg/day for approximately 7 days, then increase to the target dose of 1.2 mg/kg/day, with dose adjustments made every 7-14 days based on clinical response. 1, 2
For patients weighing >70 kg and adults, initiate atomoxetine at 40 mg/day for approximately 7 days, then increase to the target dose of 80 mg/day. 1, 2
Specific Titration Protocol
Pediatric Patients (≤70 kg):
- Week 1: 0.5 mg/kg/day 2
- Week 2 onward: Increase to 1.2 mg/kg/day (target dose) 1, 2, 3
- Maximum dose: 1.4 mg/kg/day or 100 mg/day, whichever is lower 1, 2
Adolescents/Adults (>70 kg):
- Week 1: 40 mg/day 1, 2
- Week 2 onward: Increase to 80 mg/day (target dose) 1, 2
- Maximum dose: 100 mg/day 1, 2
The research demonstrates that 1.2 mg/kg/day is as effective as 1.8 mg/kg/day and represents the appropriate initial target dose for most patients. 3 Higher doses (up to 120 mg/day in adults) have been studied and found safe, but the standard maximum remains 100 mg/day in clinical practice. 4
Administration Flexibility
Atomoxetine can be administered as a single daily dose (morning or evening) or split into two evenly divided doses to minimize side effects. 1, 2, 5 Split dosing may be particularly useful during initial titration to reduce gastrointestinal side effects like nausea. 2
Critical Timing Considerations
Maintain patients at the target dose for 4-6 weeks minimum before assessing efficacy, as atomoxetine has a delayed onset of therapeutic effect requiring 6-12 weeks for full benefit. 2, 6 This is a common pitfall—clinicians often discontinue atomoxetine prematurely due to inadequate trial duration. 6
Real-world data reveal that adult patients frequently receive suboptimal doses (averaging ~60 mg/day instead of the recommended 80 mg/day target), which may contribute to treatment failure. 6
Special Dosing Adjustments
For CYP2D6 poor metabolizers (approximately 7% of the population) or patients taking strong CYP2D6 inhibitors (certain SSRIs), reduce the dose or extend the titration interval. 1, 2 These patients achieve 10-fold higher plasma concentrations and require dosage modifications. 1
Monitoring During Titration
Assess blood pressure and heart rate at each dose adjustment, as atomoxetine causes modest increases in both parameters. 1, 2
Monitor closely for suicidal ideation, clinical worsening, and unusual behavioral changes, especially during the first few months of treatment or with dose changes, per FDA Black Box Warning. 1, 2
Track common adverse effects including nausea, decreased appetite, abdominal pain, fatigue, and somnolence, which are most prominent during initial titration. 1, 2, 5
Positioning in Treatment Algorithm
Atomoxetine is positioned as second-line therapy after stimulants for most patients, as stimulants demonstrate larger effect sizes. 2 However, atomoxetine may be considered first-line for patients with comorbid substance use disorders, tic disorders, or concerns about medication diversion. 2