What is the safe protocol to switch an adult patient taking Adderall (mixed‑amphetamine salts) 10 mg twice daily to Vyvanse (lisdexamfetamine), including appropriate wash‑out period, starting dose, contraindications, and monitoring parameters?

Switching from Adderall to Vyvanse in Adults

You can switch directly from Adderall 10 mg twice daily (20 mg total) to Vyvanse 30 mg once daily in the morning without any washout period, as both are amphetamine-based stimulants with overlapping mechanisms and no risk of dangerous interactions. 1

Conversion Dosing

• The recommended starting conversion is Vyvanse 30 mg once daily for a patient taking Adderall 20 mg total daily dose. This accounts for the prodrug formulation of lisdexamfetamine and provides comparable therapeutic coverage while avoiding under- or over-dosing. 1

• Vyvanse (lisdexamfetamine) is a prodrug that is hydrolyzed in the blood to release d-amphetamine gradually, resulting in a lower peak plasma concentration (Cmax), extended time to peak (Tmax by approximately 1 hour), and reduced inter- and intra-individual variability compared to immediate-release amphetamine. 2, 3

• The therapeutic duration of Vyvanse extends to at least 14 hours post-dose in adults, longer than any other long-acting amphetamine formulation, which eliminates the need for twice-daily dosing. 2, 4

Switch Protocol

• Discontinue Adderall 10 mg twice daily and initiate Vyvanse 30 mg the following morning—no washout or taper is required. Both medications are amphetamine-based stimulants, and direct substitution is safe. 1

• Administer Vyvanse once daily in the early morning (ideally after breakfast) to minimize sleep disturbances, as the extended duration of action can interfere with nighttime sleep if taken later in the day. 5, 4

• Allow at least one week at the initial 30 mg dose to properly evaluate therapeutic response and side effects before making any dose adjustments. This permits steady-state plasma levels and accurate assessment of symptom control. 1

Titration After Initial Switch

• If symptom control is insufficient after one week at Vyvanse 30 mg, increase by 10–20 mg increments weekly based on clinical response, with a maximum recommended daily dose of 70 mg for adults with ADHD. 1, 5

• Obtain weekly ADHD symptom ratings during titration (from the patient or a significant other) to objectively track improvement and guide dose adjustments. 6, 7

• The usual therapeutic range for adults is 30–70 mg daily; most patients achieve optimal symptom control within this range. 5, 8

Monitoring Parameters

• Measure blood pressure and pulse at baseline (before the switch) and at each dose adjustment visit, as amphetamine stimulants can cause modest increases in both parameters. 1, 5

• Assess for common adverse effects at each visit, including decreased appetite, insomnia, headache, dry mouth, anxiety, and irritability—these occur in >5% of patients and are typical of amphetamine therapy. 5, 4

• Track weight at each visit, particularly if appetite suppression is prominent, as stimulants can cause clinically significant weight loss in some adults. 5

• Monitor sleep quality and timing of dose administration; if insomnia persists, ensure Vyvanse is taken early in the morning and not later in the day. 4

Contraindications to the Switch

• Do not initiate Vyvanse (or continue any amphetamine) in patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing an MAOI, due to the risk of hypertensive crisis. 5

• Avoid Vyvanse in patients with known structural cardiac abnormalities, cardiomyopathy, serious cardiac arrhythmia, coronary artery disease, or other serious cardiac disease. 5

• Do not use in patients with known hypersensitivity to amphetamine products or other ingredients in lisdexamfetamine. 5

• Exercise caution (and consider alternative agents) in patients with uncontrolled hypertension, active psychosis or mania, or a history of stimulant abuse—though long-acting formulations like Vyvanse have lower abuse potential than immediate-release amphetamine. 5, 2, 9

Renal Dosing Adjustments

• In patients with severe renal impairment (eGFR 15–29 mL/min/1.73 m²), the maximum dose of Vyvanse is 50 mg/day. 5

• In patients with end-stage renal disease (ESRD; eGFR <15 mL/min/1.73 m²), the maximum dose is 30 mg/day. 5

Clinical Pearls

• Vyvanse's prodrug design results in a smoother pharmacokinetic profile with less potential for euphoria and lower drug-liking scores compared to immediate-release d-amphetamine, which may reduce oral abuse risk. 2, 9

• The gradual release of d-amphetamine from lisdexamfetamine hydrolysis provides more consistent symptom coverage throughout the day without the "peaks and troughs" seen with twice-daily immediate-release formulations. 2, 3

• Patients switching from twice-daily Adderall often report improved convenience and adherence with once-daily Vyvanse, as well as reduced afternoon "rebound" symptoms. 8

• If a patient does not respond adequately to Vyvanse after proper titration (up to 70 mg), consider switching to methylphenidate-based stimulants, as approximately 90% of patients respond to one stimulant class when both are tried. 6