What dose of Adderall (mixed‑amphetamine salts) immediate‑release (IR) or extended‑release (ER) is equivalent to Vyvanse (lisdexamfetamine) 60 mg?

Vyvanse 60mg Dose Equivalence to Adderall

Vyvanse 60mg is approximately equivalent to 20mg of dextroamphetamine, which translates to roughly 20-30mg of Adderall XR or 20mg total daily dose of Adderall IR (given in divided doses). However, direct dose conversion between these medications is not straightforward due to fundamental pharmacokinetic differences.

Understanding the Conversion Challenge

Lisdexamfetamine (Vyvanse) is a prodrug that must be enzymatically converted to dextroamphetamine in the blood, primarily by red blood cells 1. This creates a unique pharmacokinetic profile that differs substantially from Adderall formulations.

Key Pharmacokinetic Differences

Vyvanse's conversion mechanism produces:

• Lower peak plasma concentrations (Cmax) of dextroamphetamine compared to equivalent doses of immediate-release amphetamines 2
• Delayed time to maximum concentration (Tmax of approximately 3.5-4.4 hours for dextroamphetamine) 1
• More sustained, gradual release with less pronounced peaks 2
• Duration of effect up to 14 hours in adults 3

This translates to clinical differences:

• Vyvanse produces smaller but more sustained increases in striatal dopamine compared to IR amphetamines at equivalent doses 2
• The prodrug mechanism results in lower "drug liking" scores and reduced abuse potential 4, 2
• Less pronounced behavioral activation as dopamine concentrations increase, but maintained activity for longer periods 2

Practical Conversion Approach

From Vyvanse 60mg to Adderall

For Adderall XR:

• Start with 20-25mg Adderall XR once daily
• The 2024 AJOG guidelines indicate Adderall XR starting dose is 10mg with titration by 5mg weekly up to 50mg maximum 5
• Monitor response over 1-2 weeks before adjusting

For Adderall IR:

• Start with 10mg twice daily (20mg total daily dose)
• The 2002 practice parameter recommends starting doses of 2.5mg for amphetamines with increases of 2.5-5mg per dose 6
• Divide doses: typically morning and midday administration
• Maximum total daily dose per PDR is 40mg for amphetamines 6

Important Caveats

The conversion is not 1:1 because:

• Vyvanse 60mg does not deliver 60mg of active dextroamphetamine; the molecular weight difference means approximately 30mg of dextroamphetamine base is released 1
• The gradual conversion process creates different peak-to-trough ratios
• Individual enzymatic conversion rates vary, though inter-subject variability is relatively low (<25%) 1

Clinical monitoring priorities:

• Assess symptom control throughout the day, particularly late afternoon/evening
• Adderall IR will require redosing and may not provide the extended coverage that Vyvanse 60mg offered (up to 14 hours) 3
• Adderall XR provides 8-12 hours of coverage versus Vyvanse's longer duration
• Watch for increased side effects with IR formulations due to higher peak concentrations

Titration Strategy

When switching from Vyvanse 60mg:

1. Start conservatively with 20mg Adderall XR or 10mg IR twice daily
2. Assess response weekly using standardized rating scales (ADHD-RS or similar) 6
3. Titrate by 5mg increments for XR or 2.5-5mg per dose for IR 6
4. Monitor vital signs - blood pressure and pulse should be checked regularly 6
5. Evaluate coverage duration - patients may need supplemental IR dosing in late afternoon if switching to XR

Special Considerations

Food effects differ:

• Vyvanse exposure is minimally affected by food (only Tmax延长) 1
• Adderall formulations may have different food interactions requiring consistent administration timing

The 2024 guidelines note that lisdexamfetamine maximum dose is 70mg daily, while Adderall XR maximum is 50mg daily 5, suggesting the medications are not dose-equivalent on a mg-to-mg basis.

Practical reality: Most clinicians find that Vyvanse 60mg patients transitioning to Adderall require 25-30mg XR or 20-25mg total daily IR (divided doses) to achieve similar symptom control, though individual titration based on response and tolerability is essential.