While extended-release guanfacine is approved for children with attention deficit/hyperactivity disorder (ADHD), the medication is not well studied in children with ASD. Researchers from the Research Units on Pediatric Psychopharmacology Autism Network conducted a multisite, randomized clinical trial comparing extended-release guanfacine with placebo in children with ASD accompanied by hyperactivity, impulsiveness, and distractibility.
For the study, 53 boys and nine girls, who ranged in age from 5 to 14 years, were randomly assigned to extended-release guanfacine or placebo for eight weeks. The modal daily dose at week 8 was 3 mg/day (range: 1 mg/day to 4 mg/day) for the extended-release guanfacine group and 3 mg/day (range: 2 mg/day to 4 mg/day) for the placebo group.
The guanfacine group showed a 43.6% decline in scores on the Aberrant Behavior Checklist-hyperactivity subscale compared with a 13.2% decrease in the placebo group. The rate of positive response (much improved or very much improved on the Clinical Global Impression-Improvement scale) was 50% for the guanfacine group compared with 9.4% for the placebo group.
The most common adverse events reported by the guanfacine group included drowsiness, fatigue, and decreased appetite.
“Although symptoms of ADHD and ASD often co-occur and may reflect shared underlying genetic risk, the ADHD syndrome in ASD may differ from ADHD in children without ASD,” the researchers stated. “Children with ASD may be internally focused on topics of special interest, find little reward in matters outside of their circumscribed interest, and, consequently, pay little attention to other environmental stimuli. Hyperactivity and impulsiveness in children with ASD appear similar to the hyperactivity and impulsiveness in ADHD and are more amenable to measurement.”
For related information, see the Psychiatric News article "AACAP Updates Guidelines on Autism Spectrum Disorder."