"We know that drugs that cause euphoria are potentially abusable, and euphoria requires rapid delivery to the brain. 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," says Thomas Spencer, MD, of the MGH Pediatric Psychopharmacology Unit, the paper's lead author. "The ability to show that rate of brain delivery may determine abuse potential is important to our understanding of the safety of different formulations."
Methylphenidate and other stimulant drugs used to treat ADHD act by blocking the dopamine transporter, a molecule on brain cells that takes up the neurotransmitter dopamine, raising its level in the brain. Studies have shown that the brains of ADHD patients have abnormal regulation of dopamine, which plays a key role in the control of movement, behavior and attention. While stimulants are effective for controlling ADHD symptoms, the drugs are also subject to abuse, so the current study was designed to compare the abuse potential of two formulations of methylphenidate.
The researchers compared a traditional, quick-release form of the drug with Concerta, a formulation that is released over 12 hours to produce a gradual increase in blood levels. With Concerta, the drug passes slowly through a hole in capsul
Contact: Sue McGreevey
Massachusetts General Hospital