SAN DIEGO – Lisdexamfetamine, the recently approved once-daily medication for attention-deficit/hyperactivity disorder that appears to have low abuse potential, was safe and effective when given for a full year, and guanfacine, an investigational alpha-2A-adrenoreceptor, produced substantial improvement in a phase III trial, according to studies presented at the annual meeting of the American Psychiatric Association.
These studies were among several presented at the meeting on new ADHD medications and formulations expected to greatly broaden the number of treatments for ADHD.
Lisdexamfetamine is a prodrug of dextroamphetamine that is thought to have less abuse potential because the central nervous system is not rapidly exposed to high levels.
In the study, of 272 individuals aged 6–12 years who had been treated in previous short-term trials were followed for up to 1 year. The subjects had a mean improvement of 63% from their baseline ADHD Rating Scale score, and 95% were judged by their treating physicians to be much improved or very much improved, Dr. Ann C. Childress, a psychiatrist from Las Vegas, said in a poster presentation.
The most frequently reported adverse events in the trial were decreased appetite, headache, decreased weight, and insomnia. The study was supported by New River Pharmaceuticals Inc., Radford, Va., which is collaborating with Shire Development, and by funding from Shire.
Guanfacine, in an extended-release, once-daily-dosing formulation, was shown in a phase III clinical trial to improve all the core symptoms of ADHD, including inattention.
In the trial, 322 subjects (aged 6–17 years) with ADHD received one of four doses, ranging from 1 to 4 mg/day, or placebo, Dr. Floyd R. Sallee said in a poster presentation.
After 6 weeks, the mean reduction in the ADHD Rating Scale score for those who got active drug was 19.6 points, from a baseline of about 40 points, compared with a mean reduction of 12.2 points for the placebo group, also from a baseline of about 40 points, reported Dr. Sallee, professor of psychiatry and pediatrics at the University of Cincinnati.
In addition, investigators rated about half of patients as much improved or very much improved, compared with only about 30% of patients who got placebo.
The least-square mean improvements in the inattentive subscale, compared with placebo, ranged from 2.96 points in the 2-mg-dose group to 4.16 points for the 1-mg-dose group.