Converting from Dexmethylphenidate ER 20mg to Vyvanse
Start Vyvanse at 30mg daily and titrate upward by 10-20mg increments weekly based on symptom control, with a typical target range of 40-50mg for this conversion.
Evidence-Based Conversion Rationale
Understanding the Medication Difference
- Dexmethylphenidate ER 20mg provides the active d-isomer of methylphenidate, delivering methylphenidate-based stimulation throughout the day 1
- Vyvanse (lisdexamfetamine) is a prodrug that converts to dextroamphetamine through enzymatic hydrolysis in the blood, providing amphetamine-based stimulation for approximately 12-13 hours 2, 3, 4
- These medications work through different mechanisms—methylphenidate versus amphetamine—so direct milligram-to-milligram conversion is not appropriate 5
Recommended Starting Dose
- Begin Vyvanse at 30mg daily as the initial dose when converting from dexmethylphenidate ER 20mg 6, 2
- The 30mg starting dose represents a conservative approach that allows assessment of tolerability while providing therapeutic coverage 6, 3
- Dexmethylphenidate provides efficacy comparable to methylphenidate at half the dose, meaning 20mg dexmethylphenidate ER approximates 40mg methylphenidate ER in therapeutic effect 1
Titration Algorithm
Week-by-Week Approach
- Week 1: Start Vyvanse 30mg once daily in the morning 2, 3
- Week 2: If symptom control is inadequate, increase to Vyvanse 40mg daily 6, 3
- Week 3: If needed, increase to Vyvanse 50mg daily 6, 4
- Week 4: If still inadequate, consider increasing to 60mg daily 3, 4
- Maximum approved dose is 70mg daily, though most patients respond to 40-60mg 3, 4
Monitoring During Titration
- Assess target ADHD symptoms weekly using standardized rating scales from parents, teachers, or workplace observers 6
- Monitor for appetite suppression, insomnia, headache, and irritability—the most common adverse effects with incidence >10% 3, 4
- Check blood pressure and heart rate at each visit, as stimulants can cause cardiovascular effects 6
- Weigh the patient at each visit to objectively monitor for weight loss from appetite suppression 6
Discontinuation Protocol
- Discontinue dexmethylphenidate ER abruptly without tapering when starting Vyvanse 7
- No washout period is required between stopping dexmethylphenidate and starting Vyvanse 7
- Expect immediate therapeutic effects with Vyvanse on day 1, as stimulants provide rapid symptom control 7
Expected Efficacy and Duration
- Vyvanse provides symptom control for approximately 12-13 hours in children and 14 hours in adults, longer than most methylphenidate formulations 3, 4
- Clinical trials demonstrate ADHD rating scale score reductions of approximately 27 points in children aged 6-12 years 3
- The prodrug design provides consistent plasma concentrations throughout the day with less fluctuation than immediate-release formulations 4
- Peak dextroamphetamine concentrations occur approximately 3.5-4 hours post-dose 8, 2
Common Pitfalls to Avoid
- Never convert on a milligram-to-milligram basis—Vyvanse requires higher nominal doses than methylphenidate products due to different absorption kinetics and mechanisms 5
- Do not underdose initially—starting too low (e.g., 20mg) may lead to inadequate symptom control and premature conclusion of treatment failure 6
- Avoid excessive rapid titration—weekly increases allow proper assessment of each dose level before escalating 6, 7
- Do not assume non-response prematurely—allow at least 4 weeks at the maximum tolerated dose before concluding Vyvanse is ineffective 7
Alternative Consideration
- If inadequate response occurs after 4 weeks at maximum tolerated Vyvanse dose (up to 70mg), consider that approximately 70% of patients respond to either amphetamine or methylphenidate alone, but nearly 90% respond if both classes are tried 6
- In this scenario, switching back to a methylphenidate-based product or trying a different amphetamine formulation may be appropriate 6, 7