Vyvanse Dose Adjustment for Evening Crash
Vyvanse cannot be split or staggered to 50 mg because it is only available in fixed-dose capsules (20,30,40,50,60,70 mg), and the prodrug mechanism requires the intact capsule formulation to function properly. 1, 2
Available Dosing Options
- Titrate to the next available dose of 50 mg once daily in the morning if the current 40 mg dose provides inadequate symptom control throughout the day 3, 1
- The American Academy of Child and Adolescent Psychiatry recommends weekly dose increases of 10 mg increments when titrating lisdexamfetamine, with a maximum dose of 70 mg daily 3, 1
- The FDA label confirms lisdexamfetamine is designed for once-daily morning administration only, as it is a prodrug requiring enzymatic hydrolysis in the blood to gradually release active d-amphetamine over 12-14 hours 2, 4, 5
Why Staggered Dosing Is Not Possible
- The capsule formulation cannot be divided or taken in split doses because lisdexamfetamine's therapeutic mechanism depends on rate-limited hydrolysis by red blood cells after oral administration of the intact capsule 1, 2, 4
- Attempting to manipulate the capsule (opening, crushing, or splitting) would destroy the prodrug delivery system and could result in immediate release of the full amphetamine dose, creating safety risks 3, 2
- Unlike immediate-release stimulants that can be split or dosed multiple times daily, lisdexamfetamine's pharmacokinetic profile is specifically engineered for once-daily dosing with duration of effect up to 13-14 hours 6, 5
Management of 6 PM Crash
Option 1: Increase to 50 mg Once Daily
- Move to 50 mg lisdexamfetamine taken once in the morning to extend symptom coverage through the evening hours 3, 1
- Clinical studies demonstrate efficacy maintained through 13 hours post-dose in children and 14 hours in adults 6, 5
- Monitor for adequate symptom control in the late afternoon/evening using standardized ADHD rating scales from parents and teachers 7
Option 2: Add Short-Acting Stimulant for Evening Coverage
- If increasing lisdexamfetamine dose alone is insufficient, consider adding a small dose of immediate-release amphetamine (e.g., Adderall IR 5-10 mg) or methylphenidate in the late afternoon (around 3-4 PM) to bridge the evening period 3
- This approach maintains the long-acting morning coverage while addressing the specific evening symptom breakthrough 3
Option 3: Switch to Alternative Stimulant
- If maximum tolerated lisdexamfetamine dose (up to 70 mg) fails to provide adequate all-day coverage, consider switching to a different long-acting stimulant formulation or to a twice-daily immediate-release regimen that allows flexible dosing 3, 7
Critical Monitoring During Titration
- Assess cardiovascular parameters (blood pressure and pulse) at each dose adjustment, as amphetamines can cause dose-dependent increases 3
- Monitor for appetite suppression and weight loss by weighing the patient at each visit 7
- Evaluate sleep quality, as higher doses may worsen insomnia despite improving evening symptom control 7, 6
- Use standardized rating scales to objectively measure symptom improvement throughout the day, not just subjective reports of "crashing" 7, 6
Common Pitfall to Avoid
Do not attempt to open the capsule and divide the contents or take partial doses, as this negates the prodrug mechanism and creates unpredictable pharmacokinetics with potential safety concerns 3, 1, 2