What is the duration of action of Vyvanse (lisdexamfetamine)?

Duration of Action of Vyvanse (Lisdexamfetamine)

Vyvanse (lisdexamfetamine) has a duration of action of approximately 14 hours in adults and 13 hours in children after a single dose. 1, 2

Pharmacokinetics of Vyvanse

Vyvanse is a prodrug stimulant with unique pharmacokinetic properties:

• Mechanism of action: Lisdexamfetamine is pharmacologically inactive until converted to dextroamphetamine and the amino acid lysine through an enzymatic process predominantly associated with red blood cells 3, 4

• Absorption and conversion:

  • After oral administration, Tmax of lisdexamfetamine is reached at approximately 1 hour 3
  • Tmax of dextroamphetamine (active component) is reached at approximately 3.5-4.4 hours post-dose 3
  • Food prolongs Tmax by approximately 1 hour but does not significantly affect overall exposure 3

• Elimination:

  • Plasma elimination half-life of lisdexamfetamine is less than one hour 3
  • Plasma elimination half-life of dextroamphetamine is approximately 10-11.3 hours in adults and 8.6-9.5 hours in children 6-12 years 3

Clinical Duration of Effect

The clinical duration of action extends beyond what might be expected from the half-life alone:

• In adults, the therapeutic effects of Vyvanse continue for approximately 14 hours post-dosing 4, 1
• In children, the therapeutic effects last for approximately 13 hours post-dosing 1

This long duration of action allows for once-daily dosing, which can improve medication adherence compared to shorter-acting stimulants 4, 2.

Dosing Considerations

• Starting dose: 20-30 mg once daily in the morning 5
• Titration: Can be increased by 10 mg weekly to a maximum of 70 mg daily 5
• Administration: Can be taken with or without food, though food may delay peak effects by about 1 hour 3

Clinical Implications

The extended duration of action of Vyvanse offers several advantages:

• Provides consistent symptom control throughout the day without the need for multiple doses
• May reduce the "wearing off" effect seen with shorter-acting stimulants
• Allows coverage of ADHD symptoms into the evening hours, which can be particularly beneficial for adults with work or academic responsibilities

Potential Pitfalls

• The long duration may contribute to insomnia if taken too late in the day
• Some patients may experience appetite suppression throughout the day, which is one of the most common side effects 4
• Individual variations in metabolism may affect the actual duration of effect in specific patients

Vyvanse's 14-hour duration of action in adults makes it one of the longest-acting ADHD medications available, providing symptom control that extends from morning into the evening with a single daily dose.