Can I increase the dose of atomoxetine (Strattera) in a patient experiencing fatigue and nausea on 18mg?

Managing Atomoxetine Side Effects: Dosing Considerations

No, you should not increase atomoxetine in a patient experiencing fatigue and nausea at 18mg; instead, consider maintaining the current dose while side effects subside or reducing the dose temporarily. 1, 2

Understanding Atomoxetine Side Effects

• Fatigue and nausea are among the most common adverse effects reported with atomoxetine in clinical trials, especially during initial treatment or dose increases 1, 2
• These side effects are typically transient and often resolve with continued treatment at the same dose 1
• In FDA clinical trials, nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence were the most commonly observed adverse reactions (incidence of 5% or greater) 2

Appropriate Dosing Strategy

Current Dose Assessment

• The current 18mg dose is significantly below the usual therapeutic range and represents a starting dose 1
• Standard atomoxetine titration follows a sequential, weight-based approach with:
  • Usual starting dose: 40mg daily 1
  • Titration: Dose usually adjusted every 7-14 days 1
  • Maximum recommended dose: 1.4 mg/kg/day or 100 mg/day, whichever is lower 1

Recommended Approach

1. Maintain current dose temporarily: Allow time for side effects to subside before considering dose increases 1
2. Consider split dosing: If not already doing so, dividing the daily dose into two administrations may reduce side effect intensity 3, 4
3. Slow titration: When ready to increase, use smaller increments than standard titration to minimize side effect exacerbation 1

Alternative Strategies

• Temporary dose reduction: If side effects are severe or intolerable, temporarily reducing the dose may help with tolerability before attempting to increase again 5
• Administration with food: Taking atomoxetine with food may help reduce gastrointestinal side effects 1
• Morning vs. evening dosing: Adjusting the timing of administration based on when side effects are most problematic 4

Important Monitoring Considerations

• Monitor for improvement in side effects over 1-2 weeks at the current dose 1
• Assess for other potential causes of fatigue and nausea (e.g., concurrent medications, medical conditions) 1
• Watch for rare but serious adverse effects including:
  • Cardiovascular effects (increased heart rate and blood pressure) 1
  • Hepatic effects (rare cases of liver injury) 3
  • Suicidal ideation (black box warning, especially in children and adolescents) 1

Long-term Considerations

• Some patients may achieve adequate symptom control at lower maintenance doses after initial response 5
• In a study of maintenance treatment, patients who had a robust response to atomoxetine were able to maintain that response at a reduced dose (0.5 mg/kg/day) 5
• The goal should be to find the lowest effective dose that balances symptom control with tolerability 6

Clinical Decision Algorithm

1. First 2-3 weeks: Maintain current 18mg dose to allow adaptation to medication
2. If side effects improve: Consider gradual increase to 25mg after 2-3 weeks
3. If side effects persist: Consider split dosing before attempting dose increases
4. If side effects worsen or are intolerable: Consider temporary dose reduction to 10mg before gradually retitrating

Remember that atomoxetine typically requires 2-4 weeks for full therapeutic effect, so patience during the titration process is important 3.