Starting Dose for Adult Switching from Focalin to Vyvanse
Start with Vyvanse 30 mg once daily in the morning when transitioning from Focalin (dexmethylphenidate) to lisdexamfetamine in adults. 1, 2
Conversion Rationale
The amphetamine-to-methylphenidate conversion ratio is approximately 1:1.2 to 1:2 for equivalent therapeutic effect. 1 Since Focalin is dexmethylphenidate (the active d-isomer of methylphenidate) and Vyvanse is a prodrug of dextroamphetamine, the standard starting approach is:
- Vyvanse 30 mg is the recommended initial dose for adults, which converts to approximately 8.9 mg of active dextroamphetamine after enzymatic hydrolysis in the blood. 1, 3
- This starting dose has demonstrated robust clinical efficacy in adult ADHD trials with dose-dependent improvements in core ADHD symptoms. 3
- The 30 mg dose showed significantly greater improvement in ADHD-Rating Scale total scores compared to placebo, with significant differences evident after just 1 week of treatment. 4
Immediate Transition Protocol
No washout period is required when switching between stimulant classes, as both medications have short half-lives and can be transitioned directly. 1 You can:
- Discontinue Focalin and start Vyvanse 30 mg the following morning
- Administer Vyvanse in the morning to leverage its 13-14 hour duration of action and minimize sleep disturbances 3, 2
Titration Strategy After Initial Dose
After starting at 30 mg:
- Assess response after 1 week at the initial dose before making adjustments 1
- If symptom control is inadequate, titrate in increments of 10-20 mg at approximately weekly intervals 2
- Available doses are 30,50, and 70 mg/day for adults 5, 4
- Maximum approved daily dose is 70 mg 2
- Allow at least 4 weeks at a therapeutic dose before determining treatment failure 1
Critical Monitoring Parameters
During the transition and titration phase, monitor for:
- Common treatment-emergent adverse events: decreased appetite, insomnia, dry mouth, and headache (most are mild to moderate and transient) 5, 3
- Cardiovascular parameters: pulse and blood pressure, as stimulants can cause elevations 1
- Symptom response: using standardized ADHD rating scales or functional assessments 2
Important Clinical Considerations
Lisdexamfetamine's unique pharmacokinetics provide advantages over immediate-release formulations:
- The prodrug is therapeutically inactive until enzymatically hydrolyzed in the blood to release active dextroamphetamine 3
- This conversion is unaffected by gastrointestinal pH or transit time variations, providing consistent plasma concentrations throughout the day 3
- Duration of action extends 13-14 hours post-dosing in adults, potentially eliminating the need for afternoon doses 3
If maximum dose (70 mg) provides inadequate symptom control, consider switching to a different medication class rather than exceeding the maximum approved dose. 2