Vyvanse to Adderall Conversion
Vyvanse 20mg is equivalent to approximately 10mg of Adderall. This conversion is based on the pharmacokinetic properties of both medications and their relative potencies as ADHD treatments.
Understanding the Conversion
Lisdexamfetamine (Vyvanse) is a prodrug that is converted to dextroamphetamine in the body. The conversion factor between these medications is important to understand:
- Vyvanse (lisdexamfetamine) contains approximately 0.2948 mg of dextroamphetamine per 1 mg of lisdexamfetamine
- Therefore, 20mg of Vyvanse yields approximately 5.9mg of active dextroamphetamine
- Adderall contains a mixture of amphetamine salts (75% dextroamphetamine and 25% levoamphetamine)
- The combined potency of these mixed amphetamine salts makes 10mg of Adderall roughly equivalent to 20mg of Vyvanse
Pharmacological Considerations
The pharmacokinetic profiles of these medications differ significantly:
- Vyvanse has a delayed onset of action (approximately 1-1.5 hours longer than Adderall) 1
- Vyvanse provides a more gradual increase in amphetamine blood levels 2
- Vyvanse has a longer duration of action (13-14 hours) compared to immediate-release Adderall (4-6 hours) 3
- Extended-release Adderall XR has a duration of 8-12 hours, still shorter than Vyvanse
Clinical Implications
When switching between these medications, consider:
- Dosing schedule: Vyvanse is typically once-daily, while Adderall may require multiple daily doses (especially immediate-release formulations)
- Onset of action: Adderall works more quickly than Vyvanse
- Duration of effect: Vyvanse provides longer symptom control throughout the day
- Abuse potential: Vyvanse's prodrug mechanism may offer lower abuse potential than immediate-release Adderall 2
Important Considerations
- Individual patient response varies based on metabolism, body weight, and other factors
- When switching between medications, start with the equivalent dose and adjust based on clinical response
- Monitor for side effects including changes in blood pressure, heart rate, appetite, and sleep patterns
- Both medications are Schedule II controlled substances with significant potential for abuse 4
Dosing Equivalence Table
| Vyvanse Dose | Approximate Adderall Equivalent |
|---|---|
| 20mg | 10mg |
| 30mg | 15mg |
| 40mg | 20mg |
| 50mg | 25mg |
| 60mg | 30mg |
| 70mg | 35mg |
Remember that this conversion is approximate, and clinical response should guide final dosing decisions.