Two Phase II studies of SPD465, an investigational triple-bead mixed amphetamine salt formulation, indicate it is effective and safe for adults with attention deficit hyperactivity disorder, according to a presentation at the recent meeting of the American Association of Child and Adolescent Psychiatry.

Collectively, data demonstrated that the agent improved symptoms of the disorder in adults for up to 16 hours and had a generally well-tolerated safety profile consistent with currently marketed amphetamine products.

"If approved, triple-bead mixed amphetamine salts may be useful for maintaining adult attention deficit hyperactivity disorder symptom control throughout the day and during the evening hours, at work or at home, due to its long duration of action," said Timothy Wigal, PhD, lead investigator for both studies and associate clinical professor of pediatrics and deputy director of the Child Development Center at the University of California, Irvine.

In Study 203 (73 adults), people taking a 25-mg dose daily in the morning had significantly higher scores than subjects taking placebo as measured by the Permanent Product Measure of Performance (PERMP), the primary endpoint, 16 hours post-dose.

The test is a 10-minute, written, age-adjusted collection of 80 math problems that provides an accurate measure of a person's ability to pay attention and stay on task. Subanalyses of the number of problems attempted and the number answered correctly showed similar results.

In addition, subjects treated with triple-bead mixed amphetamine salts had significantly improved average ADHD Rating Scale (ADHD-SRS) total scores than those taking placebo at all three test times (5.5, 11, and 16.5 hours) post-dose.

Study 201 evaluated 77 adult subjects during three seven-day treatment periods at doses of 50 mg or 75 mg compared with placebo; it used an active control for test sensitivity. At both doses, drug provided significant improvement in symptom control based on PERMP and ADHD-RS scores.

With both triple-bead doses, the average PERMP total, attempted and correct scores were significantly better than with placebo at all times measured after dosing. Average ADHD-SRS total scores were significantly better for participants receiving drug than for those receiving placebo at all three test times (5.5, 11.0, and 16.5 hours) post-dose.

The investigational formulation was generally well tolerated in both studies, although two serious adverse events, chest pain with no sequelae and hypertension with no sequelae, were reported in subjects treated with 75 mg. The most frequently reported adverse events in both studies were insomnia, decreased appetite, dry mouth, headache and anorexia and were consistent with amphetamine use.