What is the maximum recommended dosage for atomoxetine (Attention Deficit Hyperactivity Disorder - ADHD) treatment?

Maximum Dosage for Atomoxetine in ADHD

The maximum daily dose of atomoxetine is 100 mg/day for adults and adolescents over 70 kg, or 1.4 mg/kg/day (whichever is lower) for children and adolescents up to 70 kg. 1

Dosing by Body Weight

Adults and Adolescents Over 70 kg

• Maximum dose: 100 mg/day 1
• Initial dose: 40 mg/day 1
• Target dose: 80 mg/day 1

Children and Adolescents Up to 70 kg

• Maximum dose: 1.4 mg/kg/day 1
• Initial dose: 0.5 mg/kg/day 1
• Target dose: 1.2 mg/kg/day 1

Critical Dosing Considerations

Titration Timeline

• Start with 40 mg/day in adults and adolescents over 70 kg 2
• Wait 6-12 weeks to achieve full therapeutic effect, unlike stimulants which work within hours 2
• Maintain patients on the target dose for 4-6 weeks before judging efficacy 2
• Increase doses in the smallest available increments at intervals of approximately 1-2 weeks 2

Dose Adjustments Required

Hepatic Impairment: 1

• Moderate hepatic impairment: Reduce to 50% of normal dose
• Severe hepatic impairment: Reduce to 25% of normal dose

CYP2D6 Poor Metabolizers or Strong CYP2D6 Inhibitor Use: 1

• Dose adjustment necessary when using potent CYP2D6 inhibitors (including many SSRIs) 3
• SSRIs can elevate serum atomoxetine levels through CYP2D6 inhibition, requiring dose reduction 3

Evidence Supporting Maximum Dosing

Dose-Response Studies

• Research demonstrates that 1.2 mg/kg/day is as effective as 1.8 mg/kg/day in children and adolescents, making 1.2 mg/kg/day the appropriate initial target dose for most patients 4
• The 1.8 mg/kg/day dose showed no additional benefit over 1.2 mg/kg/day but remained within the safe maximum of 1.4 mg/kg/day for regulatory approval 4
• Adult studies using 60,90, or 120 mg/day showed efficacy, with the FDA-approved maximum set at 100 mg/day 5, 6

Maintenance Dosing

• For patients with robust acute response, lower maintenance doses (0.5 mg/kg/day) may retain efficacy while reducing drug exposure 7
• However, this applies only to patients who first achieved response at higher doses 7

Safety Warnings at Maximum Doses

Black Box Warning: 1

• Increased risk of suicidal ideation in children and adolescents
• Monitor closely for suicidality, clinical worsening, and unusual behavioral changes, especially during initial months or at dose changes 3

Cardiovascular Monitoring: 1

• Monitor blood pressure and heart rate at baseline and regularly during treatment
• Use caution in patients with hypertension, tachycardia, or cardiovascular disease
• Atomoxetine should not be used in patients with severe cardiovascular disorders that might deteriorate with increases in heart rate and blood pressure

Hepatotoxicity: 1

• Discontinue and do not restart if jaundice or laboratory evidence of liver injury develops

Common Pitfall to Avoid

Do not exceed 100 mg/day in adults or 1.4 mg/kg/day in children, even if response seems suboptimal 1. If inadequate response occurs after 6-12 weeks at target doses, consider switching to stimulant medications (which have 70-80% response rates) rather than exceeding maximum atomoxetine doses 3. The target dose of 60-100 mg daily for adults represents the therapeutic range, with 100 mg being the absolute ceiling 3.