Switching from Vyvanse to Immediate-Release Adderall
When switching a patient from Vyvanse (lisdexamfetamine) to immediate-release Adderall (mixed amphetamine salts), convert using a 1:1 dose equivalency ratio and initiate with divided dosing 2-3 times daily, starting at the equivalent total daily dose or slightly lower if tolerability is a concern.
Dose Conversion Strategy
Since Vyvanse is a prodrug that converts to dextroamphetamine, and immediate-release Adderall contains 75% dextroamphetamine and 25% levoamphetamine, the conversion is relatively straightforward:
- Vyvanse 30 mg → Adderall IR 10-15 mg total daily dose
- Vyvanse 50 mg → Adderall IR 15-20 mg total daily dose
- Vyvanse 70 mg → Adderall IR 20-30 mg total daily dose
The guideline recommends starting Adderall IR at 2.5-5 mg doses 1, but for patients already stabilized on Vyvanse, you can use the equivalent total daily dose divided across the day.
Dosing Schedule
Administer immediate-release Adderall in divided doses:
- Morning dose after breakfast (typically the largest dose)
- Midday dose after lunch (4-6 hours after first dose)
- Optional afternoon dose (if coverage needed for homework/evening activities)
The guideline specifies that immediate-release amphetamine formulations should be dosed 2-3 times daily due to their shorter duration of action (3-4 hours) compared to Vyvanse's 12-hour duration 1, 2.
Important Considerations
Duration of Action Difference
Vyvanse provides approximately 12 hours of coverage with once-daily dosing 3, while immediate-release Adderall lasts only 3-4 hours per dose 2. This means:
- Patients will need to remember multiple daily doses
- Coverage gaps may occur if doses are missed
- Adherence may be more challenging (though in monitored settings, adherence can be maintained) 4
Titration Approach
If the patient experiences side effects with the equivalent dose:
- Start at 2.5-5 mg per dose and titrate upward weekly 1
- Increase by 2.5-5 mg increments until symptom control is achieved
- Maximum daily doses typically range up to 40 mg for adults 1
Monitoring Requirements
At baseline and follow-up:
- Blood pressure and pulse (quarterly for adults) 1
- ADHD symptom ratings (weekly during titration) 1
- Side effects assessment (appetite, sleep, cardiovascular symptoms) 1
Clinical Pitfalls to Avoid
Do not assume 1:1 bioequivalence is perfect. While Vyvanse converts to dextroamphetamine, immediate-release Adderall contains both dextro- and levo-amphetamine isomers. Some patients may require dose adjustments after the initial switch 4.
Watch for rebound symptoms. The shorter duration of immediate-release formulations means patients may experience symptom return between doses. Consider timing the doses to cover the most critical periods of the day 1.
Anticipate adherence challenges. Research shows that while adherence can be maintained in structured settings with multiple daily dosing, real-world adherence may be more problematic with immediate-release formulations compared to once-daily Vyvanse 4.
Screen for contraindications. Before switching, confirm no history of cardiovascular disease, uncontrolled hypertension, hyperthyroidism, glaucoma, or active substance abuse 1.
Alternative if Immediate-Release Adderall is Ineffective
If the patient does not respond adequately to immediate-release Adderall, consider switching to immediate-release dextroamphetamine sulfate as an alternative amphetamine formulation. A recent case report demonstrated maintained symptom control when switching from lisdexamfetamine to immediate-release dextroamphetamine during medication shortages 5. Research indicates that approximately 41% of patients may need to switch between stimulant families (methylphenidate vs. amphetamine) due to tolerability issues 6.