What is the recommended protocol for switching from Strattera (atomoxetine) to Vyvanse (lisdexamfetamine) for Attention Deficit Hyperactivity Disorder (ADHD) treatment?

Switching from Strattera to Vyvanse

You can safely switch from Strattera (atomoxetine) to Vyvanse (lisdexamfetamine) using a cross-taper approach: initiate Vyvanse at 20-30 mg once daily in the morning while gradually tapering atomoxetine over 1-2 weeks, as atomoxetine can be discontinued without rebound effects or discontinuation syndrome. 1

Switching Protocol

Initiation of Vyvanse

• Start Vyvanse at 20-30 mg orally once daily in the morning 2, 3
• Titrate by 10 mg weekly increments to a maximum of 70 mg daily based on response 2, 3

Atomoxetine Discontinuation Strategy

• Atomoxetine may be discontinued abruptly without rebound effects or discontinuation syndrome 1
• However, a gradual cross-taper over 1-2 weeks is clinically prudent to ensure smooth transition and minimize any potential withdrawal symptoms 1
• Co-administration of atomoxetine with stimulants during the switching period does not cause undue concern for adverse events, though cardiovascular monitoring (blood pressure and heart rate) is necessary 1

Timeline Considerations

• Common adverse events from atomoxetine resolve with median times of 3-53 days after discontinuation 4
• Blood pressure and heart rate increases during atomoxetine treatment return to baseline upon discontinuation 4
• Allow at least 6-8 weeks to fully evaluate the efficacy and tolerability of Vyvanse after completing the switch 1

Monitoring Parameters

During the Switch

• Monitor blood pressure and heart rate during the cross-taper period when both medications may be co-administered 1
• Watch for cardiovascular changes as both medications can affect these parameters 1, 4

After Vyvanse Initiation

• Monitor for irritability, insomnia, and changes in mood with lisdexamfetamine 3
• Track appetite changes, as decreased appetite is common with stimulants 2
• Monitor height and weight, particularly in pediatric patients 2
• Assess pulse and blood pressure regularly 2

Clinical Rationale for Switching

When to Consider This Switch

• Inadequate response to atomoxetine after appropriate trial duration (6-8 weeks minimum) 1
• Need for more robust symptom control, as stimulants have larger effect sizes than atomoxetine 2, 5
• Requirement for symptom coverage throughout the day, as Vyvanse provides extended duration of action 2

Expected Outcomes

• Approximately 75% of methylphenidate responders also respond to atomoxetine, but conversely, about 50% of methylphenidate non-responders will respond to atomoxetine 1
• While this data is specific to methylphenidate, it suggests that switching between medication classes (non-stimulant to stimulant) can yield improved responses in a substantial proportion of patients 1
• Lisdexamfetamine, as a prodrug converting to dextroamphetamine, provides predictable pharmacokinetics and extended symptom control 3

Important Caveats

Controlled Substance Status

• Vyvanse is a controlled substance, unlike atomoxetine 2, 5
• This switch may not be appropriate for patients with active substance use disorders or high risk of medication diversion 2, 5

Comorbidity Considerations

• Atomoxetine may be preferable as first-line for patients with comorbid anxiety, tics, Tourette's disorder, or substance use disorders 2
• If switching away from atomoxetine in these populations, ensure comorbid conditions are stable and closely monitored 2

Adverse Event Profile Differences

• Somnolence is more common with atomoxetine, while insomnia is more common with stimulants like Vyvanse 5
• Patients experiencing sedation on atomoxetine may actually benefit from the alerting effects of Vyvanse, but those with pre-existing sleep difficulties may experience worsening 5