What is the formulation and dosing of atomoxetine (Strattera) for attention deficit hyperactivity disorder (ADHD)?

Atomoxetine Formulation and Dosing for ADHD

Atomoxetine (Strattera) is available as capsules containing 10,18,25,40,60,80, or 100 mg of atomoxetine hydrochloride and as an oral solution (4 mg/ml), with dosing following a weight-based approach up to a maximum of 1.4 mg/kg/day or 100 mg/day, whichever is lower. 1

Formulation Details

• Atomoxetine is a selective norepinephrine reuptake inhibitor (not classified as a stimulant) that increases both noradrenaline and dopamine in the prefrontal cortex 1
• Available in two formulations:
  • Capsules: 10,18,25,40,60,80, and 100 mg strengths 1
  • Oral solution: 4 mg/ml concentration 1

Dosing Protocol

Children and Adolescents (≤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 (not to exceed 100 mg/day) 1, 2

Children and Adolescents (>70 kg) and Adults

• Initial daily dose: 40 mg 1, 2
• Target total daily dose: 80 mg 1, 2
• Maximum daily dose: 100 mg 1, 2

Administration Schedule

• Can be administered as a single daily dose or split into two evenly divided doses 3, 4
• Titration follows a sequential approach, with dose usually adjusted every 7-14 days 1
• Typical titration: Start at 40 mg daily, then increase to 60 mg, then 80 mg daily 1

Special Dosing Considerations

• Dosage adjustment required for:
  • Hepatic impairment 2
  • Patients taking strong CYP2D6 inhibitors (e.g., some SSRIs) 1, 2
  • CYP2D6 poor metabolizers (approximately 7% of population) 1
• Atomoxetine is primarily metabolized through the CYP2D6 pathway, which affects drug levels and potential side effects 1

Safety Monitoring

• Black box warning for 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 dose changes 1
  • Cardiovascular effects: increases in heart rate and blood pressure 1
  • Hepatic effects: rare cases of serious liver injury 2
  • Growth effects in pediatric patients: monitor height and weight 1

Common Adverse Effects

• Most common side effects in children and adolescents:
  • Nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence 1
• Additional side effects in adults:
  • Dry mouth, insomnia, constipation, dizziness, sweating, dysuria, sexual problems, and palpitations 5, 6

Clinical Advantages

• Not classified as a controlled substance due to negligible abuse potential 3, 4
• Particularly useful for:
  • Patients at risk of substance abuse 3, 4
  • Patients with comorbid anxiety or tics 3, 4
  • Patients who prefer not to take a controlled substance 3, 4

Pregnancy and Breastfeeding Considerations

• Limited data on use during pregnancy, but does not appear to be associated with major congenital malformations 1
• Caution advised during breastfeeding - likely present in human milk due to low molecular weight and long half-life 1