What is the recommended protocol for switching a child or young adult with Attention Deficit Hyperactivity Disorder (ADHD) from Strattera (atomoxetine) to Vyvanse (lisdexamfetamine)?

Switching from Strattera (Atomoxetine) to Vyvanse (Lisdexamfetamine)

You can switch directly from atomoxetine to lisdexamfetamine without a washout period or cross-taper, starting Vyvanse at 20-30 mg once daily in the morning and titrating by 10 mg weekly to a maximum of 70 mg daily based on response. 1

Discontinuation of Atomoxetine

• Stop atomoxetine abruptly without tapering, as it can be discontinued without rebound effects or discontinuation syndrome 2
• Patients may miss occasional doses of atomoxetine without adverse consequences, supporting the safety of abrupt discontinuation 2

Initiation of Vyvanse

• Start lisdexamfetamine at 20-30 mg orally once daily in the morning 1, 3
• Titrate by 10 mg weekly increments based on clinical response 1, 3
• Maximum dose is 70 mg daily 1, 3

Clinical Rationale for This Switch

The most common reasons to switch from atomoxetine to lisdexamfetamine include:

• Inadequate symptom control after an appropriate trial (6-12 weeks) of atomoxetine at maximum tolerated dose 4, 1
• Need for more robust symptom improvement, as stimulants demonstrate larger effect sizes than atomoxetine 4, 1, 5
• In head-to-head comparison, lisdexamfetamine achieved clinical response in median 12 days versus 21 days for atomoxetine, with 81.7% response rate versus 63.6% by week 9 5

Monitoring During the Switch

Cardiovascular parameters:

• Monitor pulse and blood pressure regularly, as both medications can increase these parameters 4
• Expect mean increases of approximately 3-4 bpm in pulse rate with lisdexamfetamine 5

Growth parameters:

• Track height and weight, particularly in pediatric patients, as stimulants can affect growth velocity more than atomoxetine 4, 1
• Lisdexamfetamine is associated with greater weight loss (mean -1.30 kg) compared to atomoxetine (mean -0.15 kg) 5

Psychiatric symptoms:

• Monitor for irritability, insomnia, and mood changes, which are more common with stimulants than atomoxetine 1, 6
• Somnolence is more common with atomoxetine, while insomnia is more common with stimulants 6

Appetite changes:

• Decreased appetite is common with lisdexamfetamine and typically more pronounced than with atomoxetine 1, 5

Important Caveats and Contraindications

Substance use considerations:

• Do not switch to Vyvanse in patients with active substance use disorders or high risk of medication diversion, as lisdexamfetamine is a Schedule II controlled substance while atomoxetine is not 4, 1
• Atomoxetine has negligible abuse potential and should remain the preferred option in these populations 4, 6

Comorbid conditions:

• Exercise caution when switching patients with comorbid anxiety, tics, or Tourette's disorder, as atomoxetine may be preferable for these conditions 4, 1
• Ensure these comorbid conditions are stable before switching and monitor closely afterward 1

Cardiac screening:

• Expand history to include Wolf-Parkinson-White syndrome, sudden death in family, hypertrophic cardiomyopathy, and long QT syndrome before initiating stimulant therapy 4

Timeline for Response

• Expect therapeutic effects within 1-2 weeks with lisdexamfetamine, significantly faster than the 6-12 weeks required for atomoxetine 4, 5
• Lisdexamfetamine provides extended duration of action throughout the day, suitable for patients requiring all-day symptom coverage 1

Alternative Approach: Combination Therapy

If atomoxetine provided partial benefit but inadequate response:

• Consider augmenting atomoxetine with lisdexamfetamine rather than switching completely 4
• Only extended-release guanfacine and extended-release clonidine have FDA approval as adjunctive therapy with stimulants, though combination with atomoxetine is used off-label 4
• Co-administration of atomoxetine with stimulants does not appear to cause undue cardiovascular effects, though monitoring remains necessary 2