Pharmacokinetics of SLI381 (ADDERALL XR), an extended-release formulation of Adderall

J Am Acad Child Adolesc Psychiatry. 2003 Jun;42(6):684-91. doi: 10.1097/01.CHI.0000046850.56865.CB.


Objective: To assess the pharmacokinetic (PK) properties of a single daily dose of Adderall (mixed amphetamine salts) and the extended-release formulation, SLI381 (ADDERALL XR), in pediatric attention-deficit/hyperactivity disorder (ADHD).

Method: Fifty-one children (aged 6-12 years) with ADHD participated in a 6-week, seven-visit, PK and pharmacodynamic study. PK sampling occurred during visit 1 and again at visit 7. At visit 1, subjects received an initial oral dose of SLI381, 20 mg. At visit 7 subjects completed 1 week of medication treatment following random assignment to once-daily orally dosed SLI381 10 mg, 20 mg, or 30 mg; Adderall 10 mg; or placebo.

Results: PK parameters evidenced substantial intersubject variability (coefficients of variation = 28-56%). Time to maximum concentration (Tmax) for SLI381 versus Adderall showed average increases of 3.0 hours for dextroamphetamine (t = -2.35, p = .04, df = 8.6) and 3.2 hours for levoamphetamine (t = -2.39, p = .04, df = 9.2). The d- and l-isomer concentrations were highly correlated and approximated a 3:1 ratio.

Conclusions: SLI381 showed extended Tmax values compared with Adderall and appears suitable for once-daily dosing. Intersubject variability underscores the need for individual dose titration.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amphetamines / pharmacokinetics*
  • Amphetamines / therapeutic use*
  • Attention Deficit Disorder with Hyperactivity / drug therapy*
  • Central Nervous System Stimulants / therapeutic use*
  • Child
  • Cluster Analysis
  • Cross-Over Studies
  • Delayed-Action Preparations
  • Double-Blind Method
  • Female
  • Humans
  • Male


  • Adderall
  • Amphetamines
  • Central Nervous System Stimulants
  • Delayed-Action Preparations
  • SLI381