The US Food and Drug Administration (FDA) has approved Vyvanse® (lisdexamfetamine dimesylate) capsules for the maintenance treatment of adults with Attention-Deficit/Hyperactivity Disorder (ADHD).  This new approval is additional to the indication for Vyvanse as a treatment for ADHD in patients aged 6 years and above.

The approval is based on results from a six-week phase IV, double-blind, multi-centre, placebo-controlled, randomized withdrawal design study which assessed the maintenance of efficacy and safety of Vyvanse in 123 adults who met DSM-IV-TR® criteria for ADHD.

Following an open-label treatment, in which patients continued to receive the same Vyvanse dose they were taking at study entry, those who maintained treatment response at week 3 entered the six-week double-blind, randomized withdrawal phase (n=116), in which they received on-going treatment with the same dose of Vyvanse (n=56), or switched to placebo (n=60).

The primary efficacy endpoint was the proportion of patients who met criteria for relapse of ADHD symptoms at end point during the double-blind, randomized withdrawal phase. Statistically significantly fewer patients met the primary endpoint - Vyvanse (8.9%) versus placebo (75%) (P<.0001).

The most common adverse effects reported in the treatment group included headache, upper respiratory tract infection, insomnia, fatigue and joint sprain. The safety profile seen in this study was consistent with that of other studies of Vyvanse.