Starting Dose of Vyvanse When Switching from Adderall 20mg
The recommended starting dose of Vyvanse for a patient switching from 20mg of Adderall is 30mg once daily. This represents an appropriate initial dose when transitioning from immediate-release Adderall to the longer-acting prodrug lisdexamfetamine (Vyvanse).
Dosing Rationale
Vyvanse (lisdexamfetamine) is a prodrug stimulant that is converted to d-amphetamine in the bloodstream through an enzymatic process predominantly associated with red blood cells 1. Unlike Adderall, which is a 3:1 mixture of d- and l-enantiomers of amphetamine salts 2, Vyvanse provides only d-amphetamine after conversion.
When transitioning from Adderall to Vyvanse, consider:
- Adderall 20mg contains approximately 15mg of d-amphetamine and 5mg of l-amphetamine
- Vyvanse 30mg provides approximately equivalent d-amphetamine exposure but with a more gradual release profile
- Vyvanse has a longer duration of action (up to 14 hours in adults) compared to immediate-release Adderall 1
Dosing Guidelines
The American Academy of Child and Adolescent Psychiatry recommends the following for stimulant medications 3:
- Starting dose for amphetamine-based products: 5-10mg daily
- Maximum daily dose: up to 50mg daily
For Vyvanse specifically:
- Available in 10mg, 20mg, 30mg, 40mg, 50mg, 60mg, and 70mg capsules
- 30mg is an appropriate starting dose when converting from Adderall 20mg
- Dose can be adjusted based on clinical response and tolerability
Administration Considerations
- Vyvanse should be administered once daily in the morning 1
- Unlike Adderall which may require multiple daily doses, Vyvanse provides extended coverage throughout the day with a single dose
- Research shows that a single morning dose of long-acting stimulants can maintain behavioral effects throughout an entire school/work day 4
- Steady-state d-amphetamine concentration is typically reached by day 5 of daily dosing 5
Monitoring and Adjustment
After initiating Vyvanse:
- Evaluate efficacy and side effects after 1-2 weeks
- Follow-up visits should occur every 3-4 weeks during the initial treatment phase 3
- Dose adjustments should be based on efficacy and side effects
- Once a stable response is achieved, follow-up can be reduced to every 3-6 months 3
Important Considerations
- Vyvanse is a prodrug with potentially reduced abuse potential compared to immediate-release stimulants 6
- The conversion from Adderall to Vyvanse is not exact due to differences in formulation and pharmacokinetics
- Some patients may require dose adjustments based on individual response
- Monitor for common stimulant side effects including decreased appetite, insomnia, and anxiety
Common Pitfalls to Avoid
- Avoid starting at too high a dose, which may increase side effects
- Don't expect identical timing of effects compared to Adderall
- Remember that Vyvanse has a longer duration of action (up to 14 hours) which may affect sleep if dosed too late in the day
- Be aware that Vyvanse contains only d-amphetamine after conversion, while Adderall contains both d- and l-amphetamine isomers