Switching from Adderall IR 30 mg Twice Daily to Vyvanse
Start Vyvanse at 50 mg once daily in the morning, which provides approximately equivalent amphetamine exposure to your current total daily dose of 60 mg Adderall IR. 1, 2
Conversion Rationale
Your current regimen delivers 60 mg total daily amphetamine (as mixed amphetamine salts). Lisdexamfetamine (Vyvanse) is a prodrug that converts to dextroamphetamine after ingestion. The conversion is not 1:1 due to pharmacokinetic differences:
- Adderall IR 60 mg/day contains approximately 37.5 mg of dextroamphetamine (the rest is levoamphetamine)
- Vyvanse 50 mg converts to approximately 29 mg of dextroamphetamine 2
- Vyvanse 60 mg converts to approximately 35 mg of dextroamphetamine
Starting at 50 mg Vyvanse is appropriate because it provides similar dextroamphetamine exposure while accounting for Vyvanse's longer duration of action (approximately 12-14 hours vs. 4-6 hours for Adderall IR) 2, 3.
Switching Method
Direct switch (no titration required):
- Stop Adderall IR completely
- Begin Vyvanse 50 mg the next morning
- Take once daily in the early morning (upon awakening) 1, 2
The guideline starting dose for Vyvanse is 20-30 mg with weekly 10 mg increases up to 70 mg maximum 1. However, since you're already on a substantial amphetamine dose, starting at 50 mg avoids unnecessary undertreating and symptom breakthrough during titration.
Titration After Switch
If symptoms are inadequately controlled after 1 week on 50 mg:
If side effects are problematic at 50 mg:
- Decrease to 40 mg and reassess after 1 week
- Can further adjust in 10 mg increments weekly 1
Key Differences to Anticipate
Duration of action:
- Vyvanse provides 12-14 hours of coverage vs. 4-6 hours per Adderall IR dose 2, 3
- You will no longer need a second dose during the day
- Evening symptom control may improve, but late-evening coverage (after 8-10 PM) may be less than with a late afternoon Adderall IR dose
Onset of action:
- Vyvanse has slower onset (peak effect at 3.5-4.5 hours) vs. Adderall IR (peak at 1-2 hours) 2
- You may notice less immediate "kick" but more sustained effect throughout the day
Pharmacokinetics:
- Vyvanse is converted to dextroamphetamine by red blood cells, providing smoother plasma levels 2
- Less potential for abuse due to prodrug formulation 4, 3
- Food delays absorption by about 1 hour but does not significantly affect total exposure 2
Monitoring
Week 1-4 after switch:
- Assess symptom control using standardized rating scales (if available in your practice)
- Monitor for common side effects: decreased appetite, insomnia, dry mouth, anxiety, increased heart rate 2
- Check blood pressure and pulse at each visit
- Document weight
Common pitfalls to avoid:
- Don't start too low (e.g., 30 mg) if already on 60 mg/day Adderall IR—this will likely cause symptom breakthrough
- Don't take Vyvanse in the afternoon—the long duration will cause insomnia
- Don't open capsules and divide doses—Vyvanse is designed for once-daily dosing; the prodrug mechanism requires intact administration 2
If Switch Is Unsuccessful
Approximately 41% of patients require switching between stimulant families (methylphenidate vs. amphetamine) due to tolerability issues 5. If Vyvanse is not well-tolerated or effective after adequate trial (4 weeks at optimal dose):
- Consider returning to Adderall IR
- Consider switching to extended-release mixed amphetamine salts (Adderall XR)
- Consider trial of methylphenidate-based stimulant
- Consider non-stimulant options (atomoxetine, guanfacine) 1
The research shows that both lisdexamfetamine and mixed amphetamine salts have similar efficacy (approximately 80% response rates), but individual tolerability varies 6. The advantage of Vyvanse is once-daily dosing, smoother coverage, and lower abuse potential 4, 3.