What is the duration of action of Adderall (amphetamine and dextroamphetamine) XR in patients with attention deficit hyperactivity disorder (ADHD)?

Duration of Action of Adderall XR

Adderall XR provides approximately 12 hours of therapeutic effect for ADHD symptom control in both children and adults. 1, 2

Pharmacokinetic Profile and Duration

The extended-release formulation of Adderall XR is specifically designed to deliver symptom control throughout a full 12-hour period, distinguishing it from immediate-release formulations that require multiple daily doses. 1, 3

• The medication achieves maximal plasma concentrations approximately 8 hours after dosing, with an average plasma half-life of approximately 12 hours. 4
• Clinical trials using analog classroom assessments demonstrated that Adderall XR (at doses of 20 mg and 30 mg) maintained significant improvements in attention, deportment, and academic performance at 10.5 and 12 hours post-dose compared to placebo. 5
• The two-stage delivery system provides rapid onset within 1.5 hours while maintaining therapeutic effects through the end of the 12-hour assessment period. 5

Clinical Evidence in Different Populations

In adults with ADHD, controlled trials confirmed the 12-hour duration of action, with statistically significant improvements in ADHD symptoms measured at both 4-hour and 12-hour time points post-dose across all dose levels (20 mg, 40 mg, and 60 mg daily). 2

• The mean effect size in adult studies was 0.8, indicating robust clinical efficacy maintained throughout the dosing interval. 2
• Symptom improvements were evident within the first treatment week and sustained throughout the 4-week study period. 2

Practical Implications for Dosing

The 12-hour duration of action eliminates the need for in-school or mid-day dosing, which represents a significant practical advantage over immediate-release formulations. 5

• Once-daily morning administration provides coverage through school hours and into post-school activities for children and adolescents. 5
• The extended duration simplifies medication management, reduces potential for dose diversion, and improves adherence compared to multiple-daily-dose regimens. 3, 5

Dose-Response Relationship

Higher doses (20-30 mg in children, up to 60 mg in adults) demonstrate both greater efficacy and longer duration of therapeutic effect compared to lower doses. 3, 5

• The 10 mg dose showed shorter duration of action compared to 20 mg and 30 mg doses in pediatric analog classroom studies. 5
• Adults with severe ADHD symptoms (baseline ADHD Rating Scale score >32) achieved significantly greater symptom reduction with the 60 mg daily dose. 2