What is the recommended dosage and administration of Strattera (atomoxetine) for treating Attention Deficit Hyperactivity Disorder (ADHD)?

Strattera (Atomoxetine) Dosing and Administration for ADHD

Atomoxetine is a second-line treatment for ADHD, reserved for patients who fail stimulants, have contraindications to stimulants, or have comorbid conditions like substance abuse risk, tics, or anxiety disorders. 1

Treatment Position

• Stimulants (methylphenidate or amphetamines) should be used as first-line therapy for ADHD, with atomoxetine reserved as second-line treatment when stimulants are ineffective, not tolerated, contraindicated, or when specific comorbidities favor non-stimulant use 1
• Atomoxetine is particularly useful in patients at risk for substance abuse, those with comorbid anxiety or tic disorders, or patients who prefer not to take a controlled substance 2, 3
• The smaller effect size of atomoxetine compared to stimulants must be weighed against its advantages: around-the-clock symptom coverage, no abuse potential, and uncontrolled substance status 1

Initial Dosing

Children and Adolescents (≤70 kg)

• Start at 0.5 mg/kg/day for approximately 3 days, then increase to the target dose of 1.2 mg/kg/day 4
• Maximum dose: 1.4 mg/kg/day or 100 mg/day, whichever is less 4
• Can be administered as a single morning dose or divided into two doses (morning and late afternoon/early evening) 4

Children and Adolescents (>70 kg) and Adults

• Start at 40 mg/day for a minimum of 3 days 4
• Target dose: 80 mg/day after the initial titration period 4
• Maximum dose: 100 mg/day 4
• Administer as a single daily dose in the morning or divide into two evenly split doses 4

Dose Adjustments

Hepatic Impairment

• Moderate hepatic impairment (Child-Pugh Class B): Reduce dose to 50% of normal 4
• Severe hepatic impairment (Child-Pugh Class C): Reduce dose to 25% of normal 4

CYP2D6 Poor Metabolizers or Strong CYP2D6 Inhibitors

• When using strong CYP2D6 inhibitors (e.g., paroxetine, fluoxetine, quinidine) or in known CYP2D6 poor metabolizers, start at the usual initial dose but only increase to the target dose of 1.2 mg/kg/day (children ≤70 kg) or 80 mg/day (>70 kg and adults) if symptoms fail to improve after 4 weeks AND the initial dose is well tolerated 4
• Poor metabolizers have 10-fold higher plasma concentrations and require more cautious dosing 3

Time to Effect and Monitoring

• Atomoxetine requires 6-12 weeks to achieve full therapeutic effect, unlike stimulants which work within hours 1
• Monitor for clinical response and tolerability before each dose increase, with weekly contact (telephone acceptable) during initial titration 5
• Systematically assess for specific side effects at each visit: decreased appetite, weight loss, insomnia, nausea, abdominal pain, headache, somnolence 5, 4
• Monitor weight regularly as weight loss is common; height and weight should be monitored in pediatric patients 4
• Monitor blood pressure and heart rate, as modest increases occur with atomoxetine 4, 3

Critical Safety Monitoring

Black Box Warning: Suicidal Ideation

• Atomoxetine carries a black box warning for increased risk of suicidal ideation in children and adolescents 4
• Patients must be monitored closely for suicidality, clinical worsening, and unusual behavioral changes, especially when starting therapy 4

Severe Liver Injury

• Discontinue atomoxetine immediately and do not restart if jaundice or laboratory evidence of liver injury develops 4

Cardiovascular Screening

• Obtain careful cardiovascular history and physical examination before starting atomoxetine 4
• Generally should not be used in children or adolescents with known serious structural cardiac abnormalities, cardiomyopathy, serious heart rhythm abnormalities, or other serious cardiac problems 4

Screen for Bipolar Disorder

• Screen all patients for bipolar disorder prior to initiating atomoxetine, as it may precipitate manic episodes 4

Common Pitfalls to Avoid

• Do not expect immediate response: Unlike stimulants, atomoxetine takes weeks to months for full effect; premature discontinuation due to perceived lack of efficacy is a common error 1
• Do not use weight-adjusted dosing in adults: Adults should use fixed dosing (40 mg starting, 80 mg target, 100 mg maximum) rather than mg/kg dosing 4
• Do not overlook CYP2D6 interactions: Failure to adjust dosing when prescribing with strong CYP2D6 inhibitors (paroxetine, fluoxetine) can lead to excessive side effects 4, 3
• Do not abruptly discontinue: While atomoxetine has low discontinuation-emergent adverse events, gradual tapering is prudent 3

Comparative Efficacy Context

• Atomoxetine is significantly less effective than extended-release methylphenidate (OROS-MPH) and extended-release mixed amphetamine salts 2, 3
• Atomoxetine does not differ significantly from immediate-release methylphenidate in efficacy, but the extended-release stimulant formulations are superior 2, 3
• The mean reduction in ADHD symptom scores with atomoxetine versus placebo is approximately 28-30% versus 18-20%, demonstrating modest but clinically meaningful benefit 6, 7