Adderall XR 30mg to Vyvanse Conversion
The equivalent dose conversion from Adderall XR 30mg to Vyvanse is 50mg, based on the pharmacologic principle that lisdexamfetamine (Vyvanse) is a prodrug that converts to dextroamphetamine at approximately a 1.5:1 to 2:1 ratio by weight.
Conversion Rationale
The conversion is based on the following pharmacologic considerations:
- Vyvanse (lisdexamfetamine) is a prodrug that is enzymatically converted to dextroamphetamine in the blood after oral administration 1, 2
- Adderall XR contains 75% dextroamphetamine salts and 25% levoamphetamine salts, meaning 30mg Adderall XR delivers approximately 22.5mg of dextroamphetamine equivalents 3
- The molecular weight difference between lisdexamfetamine and dextroamphetamine means that approximately 50mg of lisdexamfetamine yields roughly 30mg of active dextroamphetamine 1
Practical Conversion Algorithm
When switching from Adderall XR 30mg to Vyvanse:
- Start with Vyvanse 50mg once daily in the morning 4
- This represents a conservative 1:1.67 conversion ratio that accounts for the prodrug metabolism
- Morning administration is critical to minimize sleep disturbances 5, 6
- Allow at least one week to evaluate response before making any dose adjustments 5, 7
Titration After Conversion
If symptom control is inadequate after one week on Vyvanse 50mg:
- Increase by 10mg weekly increments up to the maximum of 70mg daily 4
- Do not exceed 70mg daily, as this is the FDA-approved maximum dose 4
- If 70mg provides inadequate benefit, switch to an alternative medication rather than exceeding the maximum dose 5, 7
Monitoring Requirements Post-Conversion
After switching medications, systematic monitoring is essential:
- Assess blood pressure and pulse at the first follow-up visit after conversion 5, 7
- Evaluate target ADHD symptoms using standardized rating scales 7
- Monitor for common side effects including decreased appetite, insomnia, upper abdominal pain, headache, and irritability 1, 8
- Weigh the patient at each visit to detect appetite suppression 5, 7
Clinical Advantages of This Conversion
The switch from Adderall XR to Vyvanse offers several benefits:
- Once-daily dosing with duration of effect up to 13-14 hours, potentially longer than Adderall XR 8, 9
- Lower abuse potential compared to immediate-release amphetamine formulations due to the prodrug mechanism 1
- More consistent pharmacokinetics with linear dose-response relationship 1
Common Pitfalls to Avoid
When performing this conversion, avoid these errors:
- Do not use a simple 1:1 conversion (30mg Adderall XR to 30mg Vyvanse), as this will likely result in underdosing 1
- Do not start at Vyvanse 70mg even though the patient was on a moderate Adderall XR dose—allow for titration to assess tolerability 5, 6
- Do not make dose adjustments more frequently than weekly, as insufficient time between increases prevents proper evaluation of response 5, 7
- Do not administer Vyvanse in the afternoon or evening, as this will cause insomnia 5, 6
Expected Timeline for Efficacy
After conversion to Vyvanse 50mg:
- Therapeutic effects should be evident within 1.5 hours of administration and maintained through 13 hours post-dose 8
- Full clinical response assessment requires at least one week at the new dose 5, 7
- If switching due to inadequate duration of effect with Adderall XR, patients should notice extended afternoon and early evening symptom control 8, 9