Guanfacine, an alpha-2 agonist, is sometimes prescribed off-label for ADHD and has now received official FDA approval in a new, extended- release formulation. Shire will soon market the drug under the brand name Intuniv. So how well does it work? Two randomized controlled trials have addressed this question. One trial, with a total of 345 patients, examined dosages of 2 mg, 3 mg, and 4 mg and found that Intuniv improved ADHD symptom scores significantly more than placebo. However, the drug was not more effective than placebo in treating patients with specifically inattentive ADHD symptoms or in patients ages 9 to 17. It beat placebo only for very young children (six to eight) and for patients with combined hyperactive/inattentive ADHD. Its major side effects were sedation/drowsiness /fatigue, which affected 47% - 63% of patients taking Intuniv vs. 11% of those on placebo (Biederman J et al., Pediatrics 2008;121:e73-84). A second trial of 324 patients, using 1 mg, 2 mg, 3 mg, and 4 mg doses, appeared more positive for Intuniv but did not report as much data as the first study, making it difficult to judge Intuniv’s efficacy for particular age groups or symptom domains. In this second study, Intuniv beat placebo to 12 year old patients; there was no Intuniv advantage seen in the 13 to 17 year old range. The authors did not report data separately for 6 to 8 year olds and 9 to 12 year olds, nor did they report data separately for patients with differing ADHD subtypes. Drowsiness (27% vs. 12%) and fatigue (9% vs. 3%) were more common among drug- than placebo-treated patients (Sallee FR et al., J Am Acad Child Adolesc Psychiatry 2009;48:155-165). According to online clinical trial registry entries, both trials used quality of life (QOL) measures, on which Intuniv did not outperform placebo, yet QOL measures were not mentioned in either journal publication.
TCPR's Take: Intuniv appears to be helpful primarily for younger children, especially for hyperactive symptoms of ADHD. The fact that impor- tant quality of life data were left out of the published trials (apparently because they made Intuniv appear less effective) implies that Shire has made an effort to hide negative data. We hope that future publications will present the data less selectively.
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