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Guanfacine XR effective, safe in long-term treatment of ADHD

Wednesday, December 12 2007 | Comments

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What's This? Guanfacine extended release (XR) appears to be a safe and effective treatment option for the long-term management of attention-deficit/hyperactivity disorder among children and adolescents, new data show.

Researchers performed an open-label, extension study of up to 24 months. Participants were children aged 6 to 17 years with ADHD who had participated in either of 2 previous trials of guanfacine XR. Patients received guanfacine XR beginning at 1 mg/day and titrated weekly until their optimal dose was achieved (4 mg/d maximum), or when they reached a >=30% decrease in ADHD Rating Scale-IV (ADHD-RS-IV) total symptom scores from baseline.

The primary efficacy outcome was change in ADHD-RS-IV total score measured at each monthly visit. Safety and tolerability were assessed by adverse events recording, laboratory tests, electrocardiograms, and physical examination variables. Baseline for this study was defined as the baseline from the previous study carried forward.

For the 257 patients evaluable for the efficacy measures, mean changes from baseline in ADHD-RS-IV total scores were significant (-21.6, P<.001). These improvements in ADHD-RS-IV scores were seen at week 1 with a mean change of -15.8 and continued through month 11 with a mean change of -29.8.

For the safety outcomes, 259 patients received at least 1 dose of the drug. The median duration of drug exposure was 7 months.

Overall, 23 patients (8.9%) had a treatment-emergent adverse event that led to discontinuation. The most commonly reported adverse events that led to discontinuation were somnolence (1.9%), sedation (0.8%), fatigue (0.8%), and syncope (0.8%).

The most commonly reported adverse events overall were somnolence (29.9%), headache (19.7%), upper respiratory tract infection (15.1%), fatigue (12.4%), and sedation (11.2%). Of the adverse events that were considered possibly or probably related to the study drug, the most commonly reported were somnolence (28.2%), fatigue (10.8%), sedation (10.8%), and headache (10.4%).

Additionally, 13 patients experienced 17 treatment-emergent serious adverse events, although all were brief and resolved. Of these, those that were considered possibly related or related to guanfacine XR were syncope (4 patients), loss of consciousness (1 patient), and an acute aggressive episode (1 patient).

The authors noted, however, that possible confounding causes of syncope included hot weather, dehydration, stress, and standing in line for a long time.

No clinically important effects in vital signs, ECGs, hematologic parameters, urinalyses, or physical examination were observed, although 1 patient discontinued treatment because an ECG showed conduction disturbance.

Further, small decreases in pulse rate were seen at month 1 and throughout the study but not at endpoint, while decreases in mean systolic and diastolic blood pressure were evident at week 1 and month 1 but not at endpoint. The mean change in systolic BP was -0.1 mm Hg and the mean change in diastolic BP was 0.4 mm Hg.

"Other than a 1.5% incidence of syncope, safety results were largely consistent with those of short-term, placebo-controlled studies," the authors wrote. (Sallee FR, et al. Poster 105.)

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