Starting Dose for Atomoxetine (Strattera)
The starting dose for atomoxetine is 40 mg once daily for adults and children over 70 kg, while children and adolescents up to 70 kg should start at 0.5 mg/kg/day. 1, 2, 3
Dosing Guidelines Based on Weight
For patients ≤70 kg:
- Initial dose: 0.5 mg/kg/day
- Titration: Increase after minimum 3 days
- Target dose: 1.2 mg/kg/day
- Maximum dose: 1.4 mg/kg/day or 100 mg (whichever is less)
- Administration: Can be given as a single morning dose or divided into morning and late afternoon doses
For patients >70 kg and adults:
- Initial dose: 40 mg once daily
- Titration: Increase after minimum 3 days
- Target dose: 80 mg daily
- Maximum dose: 100 mg daily
- Administration: Can be given as a single morning dose or divided into morning and late afternoon doses
Titration Schedule
- Dose is typically adjusted every 7-14 days 2
- Recommended progression: 40 mg → 60 mg → 80 mg 3
- After 2-4 additional weeks, dose may be increased to maximum 100 mg if optimal response not achieved 1
Special Populations
Hepatic Impairment 1, 4:
- Moderate impairment (Child-Pugh Class B): Reduce initial and target doses to 50% of normal dose
- Severe impairment (Child-Pugh Class C): Reduce initial and target doses to 25% of normal dose
CYP2D6 Poor Metabolizers or Patients Taking CYP2D6 Inhibitors 1, 3:
- For children/adolescents ≤70 kg: Start at 0.5 mg/kg/day, increase to 1.2 mg/kg/day only if symptoms don't improve after 4 weeks
- For patients >70 kg and adults: Start at 40 mg/day, increase to 80 mg/day only if symptoms don't improve after 4 weeks
Administration Guidelines
- Can be taken with or without food 1
- Should be taken whole, not opened 1
- Can be discontinued without tapering 1
Efficacy Considerations
- Doses of 1.2 mg/kg/day and 1.8 mg/kg/day show similar efficacy, suggesting 1.2 mg/kg/day is the appropriate target dose for most patients 5
- Some patients may maintain response with lower maintenance doses (0.5 mg/kg/day) after initial response to higher doses 6
Safety Monitoring
- Monitor for suicidal ideation, particularly during first few months of treatment or dose changes 2
- Screen for bipolar disorder before starting treatment 1
- Monitor cardiovascular parameters regularly, especially in patients on hormone therapy 3
- Monitor hepatic function periodically 3
Common Side Effects
- Gastrointestinal symptoms (nausea, vomiting, abdominal pain)
- Fatigue
- Decreased appetite
- Somnolence
Remember that atomoxetine typically takes longer to show full therapeutic effect compared to stimulants, often requiring 2-4 weeks of treatment at an adequate dose.