What is the recommended dosing when switching from Vyvanse (Lisdexamfetamine) 40mg to Adderall XR (Dextroamphetamine and Amphetamine)

Switching from Vyvanse 40mg to Adderall XR

Start Adderall XR at 15-20mg once daily in the morning, which represents approximately half the Vyvanse dose based on the established 2.5:1 conversion ratio (Vyvanse:Adderall). 1

Conversion Rationale

• Vyvanse 40mg converts to approximately 15-16mg of pure dextroamphetamine after metabolism, since lisdexamfetamine is a prodrug that requires conversion in the body 2, 3
• Using the established 2.5:1 conversion factor (Vyvanse:Adderall), a patient on Vyvanse 40mg would convert to approximately 16mg of Adderall XR 1
• In clinical practice, start with Adderall XR 15mg or 20mg once daily, as these are the available dosage strengths closest to the calculated equivalent dose 2

Discontinuation Protocol

• Discontinue Vyvanse abruptly without tapering when switching to Adderall XR - amphetamines can be stopped immediately when transitioning to another ADHD stimulant medication 4
• No washout period is required between stopping Vyvanse and starting Adderall XR, as both are amphetamine-based stimulants 4
• Begin Adderall XR the morning after the last dose of Vyvanse 2

Initial Dosing and Titration

• Start Adderall XR at 15-20mg once daily in the morning after breakfast 2, 5
• If starting at 15mg and symptom control is inadequate after one week, increase to 20mg 2
• Continue weekly dose adjustments in 5-10mg increments if needed, up to a maximum of 40-50mg daily 2, 5
• The usual therapeutic range for Adderall XR is 10-40mg daily, with most adolescents and adults responding to 20-30mg 5, 6

Monitoring During Transition

• Assess target ADHD symptoms weekly during the first 2-4 weeks using standardized rating scales (ADHD-RS-IV or similar) from both the patient and relevant observers 2, 4
• Weigh the patient at each visit to objectively monitor for appetite suppression and weight loss 2, 4
• Check blood pressure and pulse at each visit during titration, as amphetamines can increase both parameters 2
• Systematically assess for common side effects including decreased appetite, insomnia, headache, abdominal pain, irritability, and weight loss 2, 5

Expected Clinical Response

• Adderall XR provides immediate therapeutic effects within 1.5 hours of administration and maintains efficacy for approximately 12 hours 6, 7
• Peak plasma concentrations occur approximately 3 hours later with Adderall XR compared to immediate-release formulations 8
• If inadequate response occurs after 4 weeks at the maximum tolerated dose (typically 40mg), consider switching back to Vyvanse or trying a methylphenidate-based stimulant rather than further dose escalation 2, 4

Common Pitfalls to Avoid

• Do not start at the full calculated equivalent dose of 20mg if the patient has concerns about tolerability - starting at 15mg allows for safer titration 2
• Do not exceed 40mg daily without careful consideration, as doses above this threshold rarely provide additional benefit and increase side effect risk 2, 5
• Avoid dosing Adderall XR in the afternoon or evening, as this significantly increases insomnia risk due to its 12-hour duration of action 6, 7