What is the equivalent dose of Adderall (amphetamine and dextroamphetamine) for Vyvanse (lisdexamfetamine) 50 mg?

Vyvanse 50 mg to Adderall Dose Conversion

The equivalent dose of Adderall for Vyvanse 50 mg is approximately 20 mg of Adderall, based on a conversion ratio of approximately 2.5:1 (Vyvanse:Adderall). 1

Conversion Algorithm

Apply a 2.5:1 conversion factor when switching from Vyvanse to Adderall:

• Vyvanse 50 mg ÷ 2.5 = Adderall 20 mg 1
• This conversion accounts for the fact that lisdexamfetamine (Vyvanse) is a prodrug that must be enzymatically converted to active dextroamphetamine in the body 2, 3

Pharmacokinetic Considerations

Vyvanse has a delayed onset but similar peak effects compared to immediate-release Adderall:

• Lisdexamfetamine produces amphetamine plasma levels with a 0.6-hour longer lag time and reaches peak concentrations approximately 1 hour later than equivalent doses of D-amphetamine 4
• Despite the delayed onset, the maximal plasma concentrations and total drug exposure (AUC) are equivalent between lisdexamfetamine and D-amphetamine at equimolar doses 4
• The prodrug mechanism results in rate-limited hydrolysis, gradually releasing active D-amphetamine throughout the day 3, 5

Dosing Framework

Standard dosing ranges support this conversion:

• Vyvanse starting dose: 20-30 mg once daily, titrated by 10 mg weekly increments to a maximum of 70 mg daily 6, 1
• Adderall starting dose: 10 mg once daily, titrated by 5 mg weekly increments up to 50 mg daily 6
• The 50 mg Vyvanse dose falls in the mid-therapeutic range, corresponding to the 20 mg Adderall mid-range dose 1

Clinical Caveats

Important differences to anticipate when converting:

• Vyvanse provides longer duration of action (up to 12-13 hours) compared to immediate-release Adderall (4-6 hours), so patients may need twice-daily Adderall dosing to maintain symptom control throughout the day 7, 2
• Peak subjective effects occur later with Vyvanse but are similar in magnitude to Adderall at equivalent doses 4
• No washout period is required when switching between these medications as they work through the same mechanism (once converted to active amphetamine) 8

Monitor for differences in symptom control timing:

• Adderall reaches peak effect faster (approximately 1 hour earlier than Vyvanse) but wears off sooner 4
• Consider splitting the Adderall dose (e.g., 10 mg twice daily) to approximate Vyvanse's extended coverage 7