Double-blind, placebo-controlled study of the efficacy and safety of lisdexamfetamine dimesylate in adults with attention-deficit/hyperactivity disorder.

OBJECTIVE

To evaluate the efficacy and safety of 30, 50, and 70 mg/day lisdexamfetamine dimesylate compared with placebo in adults with attention-deficit/hyperactivity disorder (ADHD).

METHOD

Following a 7- to 28-day washout, 420 adults aged 18 to 55 years with moderate to severe ADHD (DSM-IV-TR criteria) were treated with 30, 50, or 70 mg/day lisdexamfetamine or placebo, respectively, for 4 weeks (N = 119, 117, 122, and 62, respectively). The 50- and 70- mg/day groups underwent forced-dose titration. The primary efficacy measure was the clinician-determined ADHD Rating Scale (ADHD-RS) total score. The study was conducted from May 2006 to November 2006.

RESULTS

Treatment groups were well matched at baseline, including in ADHD-RS scores. At endpoint, changes in ADHD-RS scores were significantly greater for each lisdexamfetamine dose than for placebo (placebo = -8.2, 30 mg/day lisdexamfetamine = -16.2, 50 mg/day lisdexamfetamine = -17.4, 70 mg/day lisdexamfetamine = -18.6; all p < .0001 vs. placebo), with no differences between doses. Significant differences relative to placebo were observed in each lisdexamfetamine group, beginning at week 1 and for each week throughout. The percentage of subjects who improved (Clinical Global Impressions-Improvement scale rating < or = 2) was significantly greater for each lisdexamfetamine dose than for placebo at each week and at endpoint (placebo = 29%, 30 mg/day lisdexamfetamine = 57%, 50 mg/day lisdexamfetamine = 62%, 70 mg/day lisdexamfetamine = 61%; all p < .01). Adverse events were generally mild and included dry mouth, decreased appetite, and insomnia.

CONCLUSION

All 3 lisdexamfetamine doses were significantly more effective than placebo in the treatment of adults with ADHD, with improvements noted within 1 week. Lisdexamfetamine was generally well tolerated by these patients.