Starting Dose of Atomoxetine (Strattera)
The recommended starting dose of atomoxetine is 40 mg once daily for adults and children over 70 kg, and approximately 0.5 mg/kg/day for children and adolescents up to 70 kg. 1, 2
Dosing Guidelines Based on Weight
For children and adolescents up to 70 kg:
- Initial dose: 0.5 mg/kg/day 1
- Titration: After a minimum of 3 days, increase to target dose of approximately 1.2 mg/kg/day 1
- Administration: Can be given as a single daily dose in the morning or divided into morning and late afternoon/evening doses 1
- Maximum dose: Should not exceed 1.4 mg/kg/day or 100 mg daily, whichever is less 1, 2
For adults and children over 70 kg:
- Initial dose: 40 mg once daily 1, 2
- Titration: After a minimum of 3 days, increase to target dose of approximately 80 mg/day 1
- Administration: Can be given as a single daily dose in the morning or divided into morning and late afternoon/evening doses 1
- Maximum dose: 100 mg daily 1, 2
Special Dosing Considerations
Hepatic Impairment
- For moderate hepatic impairment (Child-Pugh Class B): Reduce initial and target doses to 50% of normal dose 1, 3
- For severe hepatic impairment (Child-Pugh Class C): Reduce initial and target doses to 25% of normal dose 1, 3
CYP2D6 Poor Metabolizers or Patients Taking CYP2D6 Inhibitors
- For children and adolescents up to 70 kg: Start at 0.5 mg/kg/day and only increase to target dose of 1.2 mg/kg/day if symptoms don't improve after 4 weeks 1
- For adults and children over 70 kg: Start at 40 mg/day and only increase to target dose of 80 mg/day if symptoms don't improve after 4 weeks 1
Administration Guidelines
- Atomoxetine can be taken with or without food 1
- Capsules should be taken whole, not opened 1
- No tapering is required when discontinuing 1
Efficacy and Dose Response
- Clinical trials have demonstrated a graded dose-response relationship 4
- The 1.2 mg/kg/day dose has been shown to be as effective as 1.8 mg/kg/day, suggesting this is an appropriate initial target dose for most patients 4
- For maintenance treatment after achieving a robust response, a lower dose (0.5 mg/kg/day) may be effective in maintaining symptom control while reducing potential side effects 5
Safety Monitoring
- Monitor patients closely for suicidality, clinical worsening, and unusual changes in behavior, especially during the first few months of treatment or at times of dose changes 2
- Common adverse effects include nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence 2
- Atomoxetine should be used with caution during breastfeeding as it is likely present in human milk, though effects on nursing infants are unknown 2