Equivalent Dose Conversion from Methylphenidate ER to Vyvanse
Start with Vyvanse 30 mg once daily in the morning when converting from methylphenidate ER 25 mg, as there is no established direct conversion ratio between these two different stimulant classes, and this conservative starting dose allows for safe upward titration based on clinical response. 1
Rationale for Starting Dose
No standardized conversion ratio exists between methylphenidate and lisdexamfetamine (Vyvanse), as they are different stimulant classes with distinct pharmacokinetic and pharmacodynamic properties 1, 2, 3
Lisdexamfetamine is a prodrug that is hydrolyzed to d-amphetamine in the blood, providing 13-14 hours of symptom control with once-daily dosing, compared to methylphenidate ER formulations that typically provide 8-12 hours of coverage 4, 3
The usual starting dose for Vyvanse is 20-30 mg once daily in the morning, with weekly titration by 10 mg increments to a maximum of 70 mg daily 1
Titration Strategy
Initiate Vyvanse at 30 mg once daily (rather than 20 mg) because the patient is already tolerating a mid-range dose of methylphenidate ER and has demonstrated stimulant tolerability 1
Assess response after 1 week using standardized ADHD rating scales from parents/teachers or self-report 5
If inadequate symptom control, increase by 10 mg weekly up to 50 mg, then to 70 mg maximum if needed 1
Monitor blood pressure, heart rate, appetite, sleep quality, and weight at each visit during titration 1, 5
Important Clinical Considerations
No cross-taper is necessary when switching between stimulant classes—discontinue methylphenidate ER and start Vyvanse the next morning 4
Lisdexamfetamine provides significantly longer duration of action (13-14 hours) compared to most methylphenidate ER formulations (8-12 hours), which may improve all-day symptom coverage but could potentially worsen insomnia if dosed too late 4, 3
Common adverse effects include decreased appetite, insomnia, irritability, and feeding difficulty, which are generally mild and dose-dependent 1
The patient may require a higher final dose than expected based on their methylphenidate dose, as individual variability in stimulant response is significant and cannot be predicted by previous dosing 2, 6
Monitoring During Transition
Week 1: Assess ADHD symptom control, sleep quality, appetite, and cardiovascular parameters (blood pressure, heart rate) 1, 5
Weeks 2-6: Continue weekly assessments and titrate by 10 mg increments if symptom control is inadequate and adverse effects are tolerable 1
Watch for peak-related side effects (irritability, anxiety) occurring 3-5 hours post-dose, which may require dose reduction rather than increase 4