What is the appropriate starting dose of atomoxetine (Strattera) for a 16‑year‑old adolescent with concentration difficulties and cannabis use?

Starting Dose of Atomoxetine (Strattera) for a 16-Year-Old with ADHD and Cannabis Use

For this 16-year-old adolescent with concentration difficulties and active cannabis use, initiate atomoxetine at 40 mg once daily in the morning, then increase after a minimum of 3 days to a target dose of 80 mg daily. 1

Rationale for Non-Stimulant First-Line Therapy

• Active substance use is a critical consideration that shifts the treatment algorithm away from stimulants toward atomoxetine as first-line therapy. Before beginning medication treatment of adolescents with newly diagnosed ADHD, clinicians should assess for symptoms of substance use; if active substance use is identified, consider prescribing nonstimulant medications that minimize abuse potential, such as atomoxetine. 2

• Atomoxetine is an uncontrolled substance with no abuse potential, making it particularly appropriate for patients at risk of substance abuse or those with active cannabis use. 3, 4

• For patients with a substance abuse history, atomoxetine (60–100 mg daily) should be considered as first-line instead of stimulants, due to its lower abuse potential. 3

Specific Dosing Protocol for Adolescents

Initial dosing:

• For adolescents over 70 kg body weight, initiate atomoxetine at 40 mg once daily and increase after a minimum of 3 days to a target total daily dose of 80 mg. 1

• After 2 to 4 additional weeks, the dose may be increased to a maximum of 100 mg in patients who have not achieved an optimal response. 1

• The maximum recommended total daily dose in adolescents over 70 kg is 100 mg (or 1.4 mg/kg/day, whichever is less). 1

For adolescents under 70 kg:

• Start at approximately 0.5 mg/kg/day and increase after a minimum of 3 days to a target of approximately 1.2 mg/kg/day. 1

• The total daily dose should not exceed 1.4 mg/kg or 100 mg, whichever is less. 1

Administration and Timing

• Atomoxetine may be administered either as a single daily dose in the morning or as evenly divided doses in the morning and late afternoon/early evening. 1

• The medication can be taken with or without food. 1

• Atomoxetine provides "around-the-clock" symptom coverage without the peaks and valleys associated with stimulant medications, which is advantageous for maintaining consistent therapeutic effect throughout the school day and evening. 3, 4

Critical Monitoring Requirements

Baseline assessment before starting:

• Measure blood pressure and pulse, as atomoxetine can produce modest cardiovascular effects. 3, 4

• Screen for personal or family history of bipolar disorder, mania, or hypomania before initiating treatment. 1

Ongoing monitoring:

• Monitor closely for suicidality, clinical worsening, and unusual changes in behavior, especially during the first few months of treatment or at times of dose changes. The FDA has issued a black-box warning for atomoxetine due to increased risk of suicidal ideation in children and adolescents. 3, 4, 5

• Track blood pressure, heart rate, height, and weight at follow-up visits. 4, 5

• Assess for common adverse effects including nausea, decreased appetite, abdominal pain, fatigue, and somnolence, which are generally transient and less severe than with alpha-2 agonists. 4, 5

Setting Realistic Expectations About Onset

• Atomoxetine requires 6–12 weeks to achieve full therapeutic effect, unlike stimulants which work within days. 3, 4, 5

• Counsel the patient and family about this delayed timeline to prevent premature discontinuation. 4

• The target dose of 1.2 mg/kg/day (or 80–100 mg for adolescents over 70 kg) has been shown to reduce ADHD symptoms by 34–38% versus 13–15.7% with placebo. 5

Common Pitfalls to Avoid

• Do not increase the dose too rapidly. For shorter half-life medications like atomoxetine, dosage should be increased in the smallest available increments at approximately 1–2 week intervals to avoid behavioral activation, agitation, or other adverse effects. 5

• Do not assume the patient needs stimulants first. Active cannabis use is a specific indication to start with atomoxetine rather than stimulants, which carry diversion and abuse risk in this population. 2, 3

• Do not discontinue prematurely. Because atomoxetine takes 6–12 weeks for full effect, assess response only after an adequate trial period at the target dose. 4, 5

• Atomoxetine can be discontinued without tapering, unlike alpha-2 agonists which require gradual dose reduction. 4, 1

Addressing the Cannabis Use

• The presence of active cannabis use warrants referral to a subspecialist for consultative support and guidance regarding substance use treatment. 2

• Diversion of ADHD medication is a special concern among adolescents; atomoxetine's lack of abuse potential eliminates this risk. 2

• Monitor prescription refill requests and symptoms for signs of misuse or diversion of any ADHD medication by parents, classmates, or other acquaintances. 2

If Atomoxetine Fails or Is Insufficient

• If ADHD symptoms do not improve adequately after 6–12 weeks at the target dose (80–100 mg), consider switching to a long-acting stimulant formulation with lower abuse potential, such as lisdexamfetamine or OROS-methylphenidate, only after addressing the substance use with appropriate support. 2, 3

• Extended-release guanfacine or clonidine are additional non-stimulant options if atomoxetine is not tolerated or effective. 2, 3