What is the recommended dosage and administration schedule for atomoxetine in a patient with ADHD?

Atomoxetine Prescription Guidelines

For an adult patient with ADHD, prescribe atomoxetine starting at 40 mg once daily in the morning, titrate to 80 mg daily after a minimum of 7-14 days, with a maximum dose of 100 mg daily. 1, 2

Initial Prescription Details

Starting Dose:

• Adults and patients >70 kg: 40 mg once daily 1, 2
• Children/adolescents ≤70 kg: 0.5 mg/kg/day 1, 2

Administration:

• Can be given as single morning dose OR divided into two doses (morning and late afternoon/early evening) 1
• Single morning dosing provides efficacy through evening hours 3
• May be taken with or without food 1

Titration Schedule

Standard Titration:

• Maintain initial dose for minimum 7-14 days before increasing 2, 4
• Target dose: 80 mg/day (adults >70 kg) or 1.2 mg/kg/day (children ≤70 kg) 1, 2
• Increase by small increments (10-25 mg) no more frequently than every 1-2 weeks 4
• Maximum dose: 100 mg/day or 1.4 mg/kg/day, whichever is lower 1, 2

Critical Warning: Rapid dose escalation increases risk of behavioral activation, agitation, motor restlessness, insomnia, and aggression, particularly in younger patients 4

Dose Adjustments Required

Hepatic Impairment:

• Moderate impairment: Reduce to 50% of normal dose 1
• Severe impairment: Reduce to 25% of normal dose 1

CYP2D6 Poor Metabolizers or Strong CYP2D6 Inhibitors (e.g., paroxetine, fluoxetine):

• Start at 40 mg/day, titrate to 80 mg/day only after 4 weeks if needed 1
• These patients have 10-fold higher drug exposure 4, 5

Baseline and Monitoring Requirements

Before Starting:

• Blood pressure and heart rate 4, 1
• Height and weight (pediatric patients) 4, 1
• Screen for cardiovascular disease, family history of sudden cardiac death, arrhythmias 1
• Screen for bipolar disorder - atomoxetine can precipitate manic episodes 1
• Assess for narrow-angle glaucoma, pheochromocytoma (contraindications) 1

Ongoing Monitoring:

• Blood pressure and heart rate at each visit 4
• Close monitoring for suicidal ideation, especially first few months or with dose changes (FDA Black Box Warning) 1, 2
• Height and weight in pediatric patients 1
• Monitor for aggressive behavior, hostility, or unusual behavioral changes 1

Critical Safety Information for Prescription

Absolute Contraindications:

• MAOI use within 14 days 1
• Narrow-angle glaucoma 1
• Pheochromocytoma or history thereof 1
• Severe cardiovascular disorders 1
• Hypersensitivity to atomoxetine 1

Black Box Warning:

• Increased risk of suicidal ideation in children and adolescents 1
• Requires close monitoring and patient/family education 1

Expected Timeline and Patient Counseling Points

Onset of Action:

• Full therapeutic effect requires 6-12 weeks - this is critical to communicate 4, 6
• Unlike stimulants which work within hours, atomoxetine requires steady-state levels 6
• Patients must take daily without interruption to maintain benefit 6

Common Side Effects to Discuss:

• Nausea, decreased appetite, dry mouth, fatigue, abdominal pain 2, 4, 7
• Somnolence (may improve with divided dosing) 5
• Urinary hesitation, erectile dysfunction 7, 3
• Initial side effects often improve with continued treatment 4

Advantages Over Stimulants:

• Not a controlled substance - easier refills 7, 8
• No abuse potential 7, 8, 5
• Provides 24-hour symptom coverage 6, 3
• Preferred in patients with substance abuse risk, anxiety disorders, or tic disorders 6

Sample Prescription Format

Rx: Atomoxetine 40 mg capsules

• Sig: Take 1 capsule by mouth once daily in the morning
• Disp: #30 capsules
• Refills: 3 (with plan to reassess and titrate at follow-up)

Follow-up: Schedule return visit in 2-4 weeks to assess tolerability before dose increase 4