Duration of Action of Vyvanse (Lisdexamfetamine)
Vyvanse provides 13-14 hours of therapeutic effect in clinical practice, making it the longest-acting ADHD stimulant available with once-daily morning dosing. 1, 2, 3
Pharmacokinetic Profile and Onset
Lisdexamfetamine is a prodrug that remains therapeutically inactive until enzymatic hydrolysis in the blood converts it to active d-amphetamine, with this rate-limited conversion occurring predominantly via red blood cell enzymes. 1, 3
The onset of action begins within 1.5-2 hours post-dose, with measurable clinical effects demonstrated as early as 1.5 hours in controlled laboratory school studies. 2, 4
Peak therapeutic effects occur approximately 3-4 hours after administration, with the prodrug design creating a smoother plasma concentration curve compared to immediate-release amphetamines. 3
Duration of Therapeutic Coverage
In children aged 6-12 years, efficacy is maintained for 13 hours post-dose, as demonstrated in rigorous laboratory school studies measuring ADHD symptoms at multiple time points throughout the day. 2, 3
In adults, the duration extends to 14 hours post-dose, providing coverage that extends late into the day for work and evening activities. 3, 5
This represents significantly longer coverage than other long-acting stimulants: extended-release mixed amphetamine salts provide 8-9 hours, while OROS-methylphenidate (Concerta) provides 10-12 hours. 6
Clinical Advantages of Extended Duration
Single morning dosing eliminates the need for in-school or workplace administration, addressing compliance issues, stigma concerns, and the logistical challenges of multiple daily doses. 1, 6
The prodrug design provides consistent therapeutic coverage throughout the entire school/work day and into evening hours for homework, after-school activities, and family interactions without requiring supplemental afternoon doses. 1
The extended duration prevents plasma concentration troughs during unstructured times (lunch, recess, bus rides home) that occur with shorter-acting formulations. 6
Comparison to Other Stimulant Durations
Immediate-release methylphenidate and dextroamphetamine: 4-6 hours, requiring 2-3 doses daily. 7
Older sustained-release formulations: 4-6 hours of clinical action, inadequate for full-day coverage. 6
Newer extended-release methylphenidate (Ritalin LA, Metadate CD): 8 hours of action. 6
Extended-release mixed amphetamine salts (Adderall XR): 8-9 hours. 6
OROS-methylphenidate (Concerta): 10-12 hours. 6
Lisdexamfetamine (Vyvanse): 13-14 hours, the longest available. 2, 3, 5
Common Pitfalls to Avoid
Do not assume all patients require the full 13-14 hour coverage—some patients may experience insomnia or appetite suppression extending too late into the evening, particularly if dosed after early morning. 6
Avoid dosing after mid-morning to minimize insomnia risk, as the 13-14 hour duration means effects will persist into late evening if taken too late. 6
Monitor for typical stimulant adverse effects including decreased appetite (most common), insomnia, headache, and irritability, which are generally mild to moderate and transient. 2, 8, 3