What is the recommended dosing of Strattera (atomoxetine) when used alongside Vyvanse (lisdexamfetamine) for Attention Deficit Hyperactivity Disorder (ADHD)?

Dosing of Strattera (Atomoxetine) When Used Alongside Vyvanse (Lisdexamfetamine) for ADHD

When using atomoxetine (Strattera) alongside lisdexamfetamine (Vyvanse) for ADHD, the recommended dosing for atomoxetine is to start with 40 mg once daily, with titration every 7-14 days to 60 mg then 80 mg daily, with a maximum dose of either 1.4 mg/kg/day or 100 mg/day (whichever is less). 1

Atomoxetine Dosing Guidelines

• Initial dose: 40 mg orally once daily 1
• Titration schedule: Adjust dose every 7-14 days, typically to 60 mg then 80 mg daily 1
• Maximum recommended dose: The lesser of 1.4 mg/kg/day or 100 mg/day 1
• Administration: Can be given as a single daily dose or split into two evenly divided doses 2, 3

Lisdexamfetamine Dosing (For Reference)

• Initial dose: 20-30 mg orally once daily in the morning 1
• Titration schedule: Increase by 10 mg weekly 1
• Maximum dose: 70 mg daily 1

Combination Therapy Considerations

Pharmacological Rationale

• Atomoxetine is a selective norepinephrine reuptake inhibitor that works through different mechanisms than stimulants like lisdexamfetamine 2, 3
• Lisdexamfetamine is a prodrug that converts to dextroamphetamine after ingestion 1
• The combination may provide broader symptom coverage through complementary mechanisms of action 4

Clinical Considerations

• Monitor for additive cardiovascular effects as both medications can affect blood pressure and heart rate 2, 5
• Atomoxetine has a longer half-life (5.2 hours in extensive CYP2D6 metabolizers, 21.6 hours in poor metabolizers) which may complement the duration of action of lisdexamfetamine 6
• Atomoxetine typically takes longer to show full clinical response compared to stimulants (median time to first clinical response: 21 days for atomoxetine vs. 12 days for lisdexamfetamine) 5

Special Populations and Monitoring

CYP2D6 Metabolism Considerations

• Atomoxetine is primarily metabolized by CYP2D6 enzyme 6
• Poor CYP2D6 metabolizers (approximately 7% of Caucasians) may have 10-fold higher plasma concentrations of atomoxetine 6
• Consider lower doses or slower titration in known poor metabolizers 6

Monitoring Parameters

• Blood pressure and heart rate should be monitored regularly as both medications can increase these parameters 2, 5
• Weight and growth should be monitored, as both medications can cause weight loss 5
• Monitor for signs of irritability, insomnia, or changes in mood 1

Common Pitfalls to Avoid

• Avoid rapid titration of atomoxetine, as its full therapeutic effect may take several weeks to develop 5
• Do not expect immediate symptom improvement with atomoxetine as seen with stimulants; response is typically more gradual 5
• Be cautious about potential drug interactions, particularly with other medications that inhibit CYP2D6 6
• Recognize that atomoxetine has a different side effect profile than stimulants (more likely to cause somnolence rather than insomnia) 2, 3

Evidence Quality and Limitations

• Limited published research exists specifically on the combination of atomoxetine and lisdexamfetamine 4
• Most evidence for atomoxetine dosing comes from monotherapy studies rather than combination therapy 2, 3
• Case reports suggest combination therapy may be beneficial for patients with inadequate response to monotherapy, but larger controlled studies are lacking 4