While pharmacologic agents have a demonstrated efficacy in children with Attention-deficit/hyperactivity disorder (ADHD), some children have suboptimal response to a single pharmacologic agent.

A recent study by Dr. Timothy E. Wilens and colleagues, published in the January 2012 issue of the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP), is the first randomized placebo-controlled trial designed to assess efficacy and safety of guanfacine extended release (GXR) as an adjunct to psychostimulants in children and adolescents diagnosed with ADHD who had a suboptimal response to a psychostimulant alone.

As reported in the article "A Controlled Trial of Extended-release Guanfacine and Psychostimulants for Attention-deficit/hyperactivity disorder," Wilens and colleagues conducted a nine week multicenter, double-blind, placebo-controlled, dose-optimization study, with participants in 59 study sites who continued their stable dose of psychostimulant given in the morning and were randomized to receive GXR in the morning, GXR in the evening, or placebo.

For both morning and evening administration of GXR, subjects receiving GXR plus a psychostimulant showed significantly greater improvement from baseline to endpoint, as measured by the ADHD-Rating Scale IV total score, compared with subjects receiving placebo plus a psychostimulant. In particular, the inattention subscale rating and the hyperactivity/ impulsivity subscales of the ADHD-RS-IV showed significantly greater improvements from baseline in subjects receiving GXR with a psychostimulant compared with subjects receiving placebo plus psychostimulant. Significant benefits of adjunctive administration were observed whether GXR was administered in the morning or evening. No new safety signals emerged after adjunctive administration of GXR with psychostimulants compared with psychostimulants alone.

Reflecting on their research findings, Wilens and colleagues stated, "The results of this study support the hypothesis that adjunctive administration of the selective alpha2A-adrenoceptoragonist, GXR, to a psychostimulant in subjects with suboptimal response to psychostimulants reduces ADHD symptoms over placebo with a psychostimulant."