What is the recommended dosing for atomoxetine (Strattera)?

Atomoxetine Dosing for ADHD

Start atomoxetine at 0.5 mg/kg/day (or 40 mg/day if >70 kg), increase after 3 days to a target dose of 1.2 mg/kg/day (or 80 mg/day if >70 kg), with a maximum of 1.4 mg/kg/day or 100 mg/day, whichever is lower. 1

Initial Dosing Strategy

For Children and Adolescents ≤70 kg:

• Starting dose: 0.5 mg/kg/day 1
• Target dose: 1.2 mg/kg/day after minimum 3 days 1
• Maximum dose: 1.4 mg/kg/day or 100 mg/day, whichever is less 1
• Titration interval: Adjust every 7-14 days 2

For Children and Adolescents >70 kg and Adults:

• Starting dose: 40 mg/day 1
• Target dose: 80 mg/day after minimum 3 days 1
• Optional increase: May increase to 100 mg/day after 2-4 additional weeks if response inadequate 1
• Maximum dose: 100 mg/day 1

Administration Options

Atomoxetine can be given as a single morning dose OR divided into two doses (morning and late afternoon/early evening). 1 Dividing the dose may reduce gastrointestinal side effects, particularly during rapid titration 3. The medication can be taken with or without food 1.

Important: Capsules must be swallowed whole and should not be opened 1.

Special Dosing Situations

Hepatic Impairment:

• Moderate hepatic impairment (Child-Pugh Class B): Reduce initial and target doses to 50% of normal 1
• Severe hepatic impairment (Child-Pugh Class C): Reduce initial and target doses to 25% of normal 1

CYP2D6 Poor Metabolizers or Strong CYP2D6 Inhibitor Use:

For patients taking strong CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine) or known CYP2D6 poor metabolizers 1:

• Children/adolescents ≤70 kg: Start at 0.5 mg/kg/day, increase to 1.2 mg/kg/day only if symptoms fail to improve after 4 weeks and initial dose is well tolerated 1
• Children/adolescents >70 kg and adults: Start at 40 mg/day, increase to 80 mg/day only if symptoms fail to improve after 4 weeks and initial dose is well tolerated 1

Monitoring Requirements

Cardiovascular Monitoring:

• Obtain cardiac history (personal and family) before initiating treatment 3
• Perform ECG if cardiac risk factors are present 3
• Monitor blood pressure and heart rate regularly throughout treatment 3

Psychiatric Monitoring:

• Screen for bipolar disorder, mania, or hypomania (personal or family history) before starting 1
• Monitor for suicidal ideation closely, especially during first few months or with dose changes, per FDA black box warning 3, 2

Growth Monitoring:

• Monitor for potential growth delays in first 1-2 years (typically returns to expected measurements after 2-3 years) 3

Expected Timeline and Efficacy

Full therapeutic effects may take 6-12 weeks to develop, requiring patience during initial treatment 2. This delayed onset is a key difference from stimulants, which work within hours 2. The effect size of atomoxetine is approximately 0.7 compared to stimulants' effect size of 1.0 3.

Common Adverse Effects

Gastrointestinal (most common):

• Decreased appetite, nausea, vomiting, abdominal pain 3, 2
• More likely with rapid dose escalation 3

Neurological:

• Initial somnolence, headache, dizziness, fatigue 3, 2

Rare but Serious:

• Extremely rare hepatitis 3
• Increased risk of suicidal ideation in children and adolescents 3, 2

Clinical Positioning

Atomoxetine may be considered as first-line treatment in specific situations 3:

• Patients with comorbid or at-risk substance use disorders 3
• Patients with Tourette's syndrome or tics 3
• Patients requiring "around-the-clock" symptom control without stimulant peaks and valleys 3
• Patients experiencing sleep problems on stimulants, particularly with autism spectrum disorder comorbidity 3

Discontinuation

Atomoxetine can be discontinued without tapering 1.