A delayed-release version of a drug to treat attention-deficit hyperactivity disorder (ADHD) appears less likely to be abused than other ADHD stimulants, according to a new study.

Researchers at Massachusetts General Hospital studied patients receiving Concerta, a once-daily dose of the ADHD drug methylphenidate, and found that they did not report experiencing or enjoying the euphoric side-effects common with the rapid-release version of the drug.

The Concerta patients were compared to a group that received the rapid-release version of the drug. Both groups were comprised of adults who did not have ADHD.

"We know that drugs that cause euphoria are potentially abusable, and euphoria requires rapid delivery to the brain," said lead researcher Thomas Spencer, M.D. "Using sophisticated PET scan imaging, we were able to examine the rate of delivery of both rapid- and delayed-release formulations of methylphenidate and correlate those results with how the drugs felt to study volunteers. The ability to show that rate of brain delivery may determine abuse potential is important to our understanding of the safety of different formulations."

The research appears in the March 2006 issue of the American Journal of Psychiatry.