What is the equivalent dosing of Vyvanse (lisdexamfetamine) for a patient taking 60 mg of Aptensio (atomoxetine)?

Equivalent Dosing of Vyvanse for a Patient Taking 60 mg Aptensio

The equivalent dose of Vyvanse (lisdexamfetamine) for a patient taking 60 mg of Aptensio XR (methylphenidate) is approximately 50 mg of Vyvanse.

Medication Conversion Rationale

When converting between different ADHD medications, it's important to understand that these are different chemical classes with distinct mechanisms of action:

• Aptensio XR contains methylphenidate, which primarily blocks dopamine and norepinephrine reuptake
• Vyvanse contains lisdexamfetamine, a prodrug of dextroamphetamine, which increases the release of dopamine and norepinephrine

Conversion Approach

1. Methylphenidate to Amphetamine Conversion:

   • Based on clinical guidelines, methylphenidate doses are typically converted to amphetamine products at approximately a 2:1 ratio 1
   • 60 mg of methylphenidate (Aptensio XR) would therefore be equivalent to approximately 30 mg of immediate-release amphetamine

2. Amphetamine to Lisdexamfetamine Conversion:

   • Lisdexamfetamine is converted to dextroamphetamine in the body
   • The conversion factor from immediate-release amphetamine to lisdexamfetamine is approximately 1:1.6 2
   • Therefore, 30 mg of amphetamine would convert to approximately 50 mg of lisdexamfetamine (Vyvanse)

Clinical Considerations for Switching

Efficacy Comparison

• Lisdexamfetamine has demonstrated faster and more robust treatment response compared to non-stimulants like atomoxetine in clinical trials 3
• Vyvanse has shown efficacy from 1.5 hours post-dose through 13 hours, providing all-day symptom control 4

Dosing Schedule

• Begin with 30 mg of Vyvanse if the patient has never taken amphetamine products before
• If converting directly from Aptensio 60 mg, start with 50 mg of Vyvanse
• Administer Vyvanse once daily in the morning
• Titrate by 10-20 mg weekly as needed, up to a maximum of 70 mg daily

Monitoring Parameters

• Monitor blood pressure and heart rate at baseline and periodically during treatment
• Track weight changes, as Vyvanse is associated with weight loss (mean 1.30 kg in clinical trials) 3
• Assess sleep quality and appetite regularly, as these are common side effects

Practical Switching Protocol

1. Direct Switch Option:

   • Discontinue Aptensio XR
   • Start Vyvanse 50 mg the next morning

2. Cross-Titration Option (for patients with concerns about transition effects):

   • Week 1: Reduce Aptensio XR to 40 mg while starting Vyvanse 30 mg
   • Week 2: Discontinue Aptensio XR and increase Vyvanse to 50 mg

Common Pitfalls to Avoid

• Underdosing: Starting with too low a dose of Vyvanse may result in inadequate symptom control
• Timing issues: Vyvanse should be administered in the morning to prevent insomnia
• Abrupt discontinuation: While Vyvanse can be stopped without tapering, monitoring for rebound symptoms is recommended
• Inadequate trial period: Allow at least 6-8 weeks to fully evaluate Vyvanse efficacy 5

Remember that individual responses to medication vary, and dose adjustments may be necessary based on clinical response and tolerability.