Switching from Adderall 30 mg to Vyvanse
Start Vyvanse at 50 mg once daily in the morning, as this provides approximately equivalent therapeutic effect to Adderall 30 mg daily. 1
Conversion Rationale
Lisdexamfetamine (Vyvanse) is a prodrug that is enzymatically converted to dextroamphetamine in red blood cells 2. The conversion ratio is approximately 1.5:1 to 2:1 (Vyvanse:Adderall), meaning:
- Adderall 30 mg ≈ Vyvanse 50-60 mg
Starting at 50 mg is appropriate because:
- It provides comparable amphetamine exposure to 30 mg Adderall
- Allows room for upward titration if needed (maximum 70 mg) 1
- Minimizes risk of under-treatment during transition
Switching Protocol
Direct switch (no washout required):
- Stop Adderall on day 1
- Start Vyvanse 50 mg the next morning
- No tapering or overlap period needed 1
Timing: Administer Vyvanse once daily in the morning after waking 1, 2. Unlike Adderall which may require multiple daily doses, Vyvanse provides 12-14 hour coverage from a single morning dose 3.
Titration Schedule
If 50 mg provides inadequate symptom control after 1 week:
Key Pharmacokinetic Differences
Vyvanse advantages over Adderall:
- Smoother effect profile: Prodrug activation provides gradual onset, reducing "peaks and valleys" 2
- Longer duration: 12-14 hours vs 4-6 hours for immediate-release Adderall 3
- Lower abuse potential: Requires enzymatic conversion; cannot be crushed/snorted for rapid effect 5, 2
- Once-daily dosing: Improves adherence compared to multiple daily Adderall doses 6
Time to peak effect:
- Lisdexamfetamine peaks at ~1 hour
- Active dextroamphetamine peaks at ~3.5-4.5 hours post-dose 2
Monitoring Requirements
Cardiovascular monitoring (essential):
- Baseline blood pressure and heart rate before switching
- Recheck at 1-2 weeks, then quarterly 7, 6
- Amphetamines increase SBP by ~2 mmHg and DBP by ~2 mmHg 8
- Heart rate increases by ~4 beats/minute 8
Symptom assessment:
- Evaluate ADHD symptom control at 1 week, then monthly 6, 9
- Use standardized rating scales (ADHD-RS, CGI-S) 10
Common adverse effects to monitor:
- Decreased appetite (most common)
- Insomnia (dose in morning to minimize)
- Headache, irritability
- Nausea (more common with Vyvanse initially) 6, 11
Clinical Pitfalls to Avoid
Don't underdose: Starting too low (e.g., 30 mg Vyvanse) will likely result in inadequate symptom control and patient dissatisfaction, as this provides less amphetamine exposure than their previous 30 mg Adderall 1.
Don't overlap medications: No need to taper Adderall or overlap with Vyvanse—direct switch is appropriate 1.
Food effects: Unlike some medications, food does not significantly affect Vyvanse absorption (only delays Tmax by ~1 hour), so it can be taken with or without food 2.
Afternoon/evening coverage: If patient needs symptom control beyond 12-14 hours, consider adding low-dose immediate-release amphetamine in late afternoon rather than increasing Vyvanse dose 5.
Special Considerations
Substance use concerns: Vyvanse has lower diversion/abuse potential than immediate-release Adderall due to its prodrug formulation, making it preferable in patients with substance use history 5, 6.
Renal impairment: Vyvanse requires dose adjustment in severe renal impairment (CrCl 15-30 mL/min: maximum 50 mg; CrCl <15 mL/min: maximum 30 mg) 2.
Pregnancy: Both medications are similar amphetamine-based products with comparable safety profiles in pregnancy (possible small increased risks of gastroschisis and preeclampsia, though absolute risks remain low) 1.