What is the recommended treatment and dosage of Atomoxetine (Strattera) for Attention Deficit Hyperactivity Disorder (ADHD)?

Atomoxetine Treatment for ADHD: Dosage and Recommendations

Atomoxetine should be used as a second-line therapy for ADHD after stimulants, with a maximum recommended dosage of 1.4 mg/kg/day or 100 mg/day (whichever is lower), following a weight-based titration approach. 1, 2

Dosing Guidelines

Children and Adolescents (up to 70 kg)

• Initial daily dose: 0.5 mg/kg 2
• Target total daily dose: 1.2 mg/kg 2
• Maximum daily dose: 1.4 mg/kg 2
• Dosing should follow a sequential, weight-based approach 1

Adults and Children/Adolescents over 70 kg

• Initial daily dose: 40 mg 2
• Target total daily dose: 80 mg 2
• Maximum daily dose: 100 mg 2

Administration Options

• Can be administered as a single daily dose or split into two evenly divided doses 3, 4
• May be taken with or without food 2
• Available in capsules containing 10,18,25,40,60,80, or 100 mg of atomoxetine hydrochloride, as well as oral solution (4 mg/ml) 1

Efficacy and Mechanism of Action

• Atomoxetine is a selective norepinephrine reuptake inhibitor that increases both noradrenaline and dopamine in the prefrontal cortex 1
• Provides "around-the-clock" effects without the peaks and valleys associated with stimulants 5
• Has a smaller effect size compared to stimulants (first-line treatments) 1, 5
• Onset of therapeutic effect is delayed (6-12 weeks) compared to stimulants 1, 5
• Studies show significant improvements in ADHD symptoms compared to placebo, with mean reductions in ADHD symptom scores of approximately 28-30% versus 18-20% for placebo 3, 4

Special Considerations

Metabolism and Drug Interactions

• Primarily metabolized through the cytochrome P450 2D6 (CYP2D6) pathway 1
• Selective serotonin reuptake inhibitors can elevate serum atomoxetine levels 1
• Dosing adjustments needed for patients with hepatic impairment, those taking strong CYP2D6 inhibitors, or known CYP2D6 poor metabolizers 2

Safety Monitoring

• BLACK BOX WARNING: Increased risk of suicidal ideation in children and adolescents 2
• Monitor closely for suicidality, clinical worsening, and unusual changes in behavior, especially during the first few months of treatment or at times of dose change 1, 2
• Monitor vital signs, particularly blood pressure and heart rate 1, 2
• Monitor height and weight in pediatric patients 2
• Watch for potential adverse effects including:
  • Decreased appetite, nausea, vomiting 1
  • Fatigue, somnolence 1
  • Abdominal pain 1
  • Headache 1
  • Possible allergic reactions 2

Advantages Over Stimulants

• Not a controlled substance; carries negligible risk of abuse or diversion 3, 4
• May be preferred in patients with:
  • Comorbid substance use disorders 1, 5
  • Comorbid tic disorders or Tourette's syndrome 1, 5
  • Sleep disturbances that could be exacerbated by stimulants 5
  • Disruptive behavior disorders 1, 5

Contraindications

• Hypersensitivity to atomoxetine or other constituents of the product 2
• Use within 2 weeks after discontinuing MAOIs 2
• Narrow-angle glaucoma 2
• Pheochromocytoma or history of pheochromocytoma 2
• Severe cardiovascular disorders 2

Clinical Pearls

• Titration should occur in weekly increments to reach the target dose 1
• Efficacy assessment should be conducted after 6-12 weeks due to delayed onset of action 5
• Atomoxetine can be an appropriate choice for patients requiring 24-hour symptom coverage 5
• In clinical trials, atomoxetine at doses of 1.2 mg/kg/day and 1.8 mg/kg/day showed similar efficacy, suggesting 1.2 mg/kg/day as an appropriate initial target dose for most patients 6