Duration of Action of Adderall Extended Release
Adderall XR (extended-release) provides approximately 12 hours of therapeutic coverage with a single daily dose. 1, 2
Pharmacokinetic Profile
The extended-release formulation uses a dual-bead delivery system that releases medication in two phases: immediate-release beads deliver the first half of the dose upon ingestion, while delayed-release beads begin releasing the second half approximately 4 hours later. 1
Onset and Peak Effects
- Onset of action occurs within 1.5 hours after administration, providing rapid symptom control comparable to immediate-release formulations. 1
- Time to maximum concentration (Tmax) is delayed by approximately 3 hours compared to immediate-release Adderall, with peak plasma levels occurring around 8 hours after dosing. 3, 4
- The average plasma half-life is approximately 12 hours for both immediate-release and extended-release formulations. 3
Duration Considerations
- The 12-hour duration of action allows for once-daily morning dosing, eliminating the need for midday administration during school or work hours. 1, 2
- Morning administration is essential to prevent sleep disturbances, as the 12-hour duration could interfere with nighttime sleep if taken later in the day. 5
Clinical Context
The bioavailability of Adderall XR 20 mg is comparable to immediate-release Adderall 10 mg given twice daily, maintaining the same 3:1 ratio of dextroamphetamine to levoamphetamine. 1
Important Caveats
- Substantial intersubject variability exists in pharmacokinetic parameters (coefficients of variation 28-56%), necessitating individual dose titration rather than relying on weight-based dosing. 4
- Food intake does not significantly affect the rate or extent of absorption with the extended-release formulation. 3
- The extended-release formulation provides more consistent symptom control throughout the day compared to the immediate-release version, which typically lasts only 3-4 hours per dose. 6