Switching from Adderall 10mg Twice Daily to Vyvanse
Start Vyvanse at 30 mg once daily in the morning, then titrate by 10-20 mg weekly based on symptom control and tolerability, with a target dose range of 50-70 mg daily. 1
Conversion Rationale
Your patient is currently taking 20 mg total daily dose of mixed amphetamine salts (Adderall). While there is no precise 1:1 conversion ratio between Adderall and Vyvanse (lisdexamfetamine), the FDA-approved starting dose for Vyvanse is 30 mg once daily regardless of prior stimulant use 1. This approach is supported by recent guideline recommendations that specify starting at 20-30 mg daily 2.
The key advantage here: Vyvanse is a prodrug that must be enzymatically converted to d-amphetamine in the blood, resulting in a smoother pharmacokinetic profile with lower peak concentrations and extended duration of action (up to 14 hours in adults) compared to immediate-release formulations 3, 4.
Titration Protocol
Following the FDA label and clinical guidelines 1:
Week 1: Start 30 mg once daily in the morning
Week 2-4: Increase by 10-20 mg weekly intervals based on:
- Symptom improvement (use ADHD rating scales)
- Tolerability (monitor for dose-limiting adverse effects)
- Patient's functional needs throughout the day
Target dose: 50-70 mg daily (most patients achieve optimal response in this range) 5
Maximum dose: 70 mg daily 1
Important Clinical Considerations
Prior amphetamine use does not affect dose-response: Research specifically examining adults symptomatic on prior amphetamine therapy showed similar improvements with Vyvanse titration as treatment-naïve patients 6. This means you should follow standard titration regardless of the patient's current Adderall dose.
Timing matters: Administer in the morning only—afternoon doses increase insomnia risk 1. The extended 14-hour duration in adults means a single morning dose typically covers the entire day 3, 4.
Flexible titration is superior: Meta-analyses demonstrate that flexible-dose titration (adjusting based on symptom control and tolerability) produces better efficacy and acceptability compared to fixed-dose approaches 7. Don't hesitate to increase doses if symptoms persist and the medication is well-tolerated.
Monitoring Parameters
- Baseline assessment: Cardiac history, blood pressure, pulse, family history of sudden death or arrhythmia 1
- Each visit: ADHD symptom scales, adverse effects, vital signs
- Common adverse effects (≥5% incidence): Decreased appetite, dry mouth, insomnia, anxiety, irritability, nausea 1
Common Pitfalls to Avoid
Underdosing: Many clinicians stop at 30-40 mg when patients could benefit from higher doses. Research shows incremental efficacy benefits continue through the full FDA-approved range when using flexible titration 7. If symptoms persist and the medication is tolerated, continue titrating.
Renal impairment: If creatinine clearance is 15-30 mL/min, maximum dose is 50 mg daily; if <15 mL/min (ESRD), maximum is 30 mg daily 1.
Drug interactions: Urinary alkalinizing agents (e.g., sodium bicarbonate) increase amphetamine blood levels, while acidifying agents (e.g., ascorbic acid) decrease levels—adjust Vyvanse dose accordingly 1.