Adult Dosing for Strattera (Atomoxetine)
Start atomoxetine at 40 mg orally once daily, titrate to 60-80 mg daily after 7-14 days, with a maximum dose of 100 mg/day or 1.4 mg/kg/day (whichever is less). 1
Initial Dosing Strategy
- Begin with 40 mg orally once daily as the standard starting dose for adults 1
- Atomoxetine can be administered as a single daily dose or split into two evenly divided doses (morning and late afternoon/early evening) 2, 3
- Single morning dosing provides symptom control throughout the waking hours and into the evening 4
Titration Schedule
- Increase dose every 7-14 days based on clinical response and tolerability 1
- Standard titration progression: 40 mg → 60 mg → 80 mg daily 1
- In clinical trials, effective doses ranged from 60-120 mg/day, with most patients responding to 60-90 mg/day 2, 3
Maximum Dosing
- Total maximum dose is the lesser of 1.4 mg/kg/day or 100 mg/day 1
- Clinical trials used doses up to 120 mg/day, though this exceeds typical guideline recommendations 2, 3
Special Populations and Dose Adjustments
CYP2D6 Poor Metabolizers
- Poor metabolizers have 10-fold higher steady-state plasma concentrations compared to extensive metabolizers 5
- Despite higher drug levels, adverse event frequency and severity are similar between metabolizer phenotypes 5
- Consider starting at lower doses if CYP2D6 poor metabolizer status is known, though routine dose adjustment is not required 6
Renal Insufficiency
- No dose adjustment needed for any degree of renal insufficiency, including end-stage renal disease 6
- Patients with end-stage renal disease have approximately 65% higher systemic exposure, but when corrected for mg/kg dosing, exposure is similar to healthy subjects 6
Hepatic Insufficiency
- Reduce dose in patients with hepatic impairment due to increased atomoxetine exposure 5
Concomitant CYP2D6 Inhibitors
- When co-administered with potent CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, quinidine), atomoxetine clearance is reduced in extensive metabolizers 5
- Consider dose reduction or slower titration when combining with strong CYP2D6 inhibitors 5
Clinical Response Monitoring
- Assess symptom improvement using standardized rating scales such as the Conners' Adult ADHD Rating Scale (CAARS) 2, 3
- In clinical trials, atomoxetine produced 28-30% reduction in total ADHD symptom scores compared to 18-20% with placebo 2, 3
- Monitor blood pressure and heart rate at baseline and during treatment, as modest increases may occur 2, 3
- Continued efficacy has been demonstrated for up to 34 weeks in extension studies 2, 3
Common Pitfalls and Caveats
- Atomoxetine has a slower onset of action compared to stimulants; full therapeutic effect may take several weeks 4
- Most common adverse events include dry mouth, insomnia, nausea, decreased appetite, constipation, dizziness, and sexual dysfunction 2, 3
- Adverse events are generally mild to moderate and often transient, particularly gastrointestinal symptoms 4, 7
- No evidence of abuse potential or rebound symptoms upon discontinuation, making it particularly useful for patients with substance abuse history 2, 3
- Atomoxetine is not a controlled substance, allowing for more convenient repeat prescriptions during long-term treatment 2, 3
Advantages in Specific Clinical Contexts
- Preferred first-line option for adults with ADHD who have comorbid substance abuse risk, anxiety disorders, or tic disorders 3, 4
- Does not exacerbate anxiety symptoms in patients with comorbid anxiety disorders 6
- Does not worsen tics in patients with comorbid Tourette's disorder 6
- Black box warning exists for suicidal ideation, particularly in pediatric populations; monitor for emergence of suicidal thoughts 4