March 9, 2006 - Surveys suggest that Ritalin abuse is a growing problem among teens in the U.S., but there is increasing evidence that the risk of abuse is much lower with newer, time-released versions of the stimulant most commonly used to treat attention deficit hyperactivity disorder.
Brain imaging studies and blood tests conducted by researchers at Massachusetts General Hospital showed that the widely prescribed once-a-day ADHD drug Concerta acts differently in the body than the rapid-release form of Ritalin, even though both drugs contain the same active ingredient -- the stimulant methylphenidate.
As expected, the tests showed that the delayed-released drug took longer to reach peak effective levels within the brain and body and the regulating effects lasted longer than with the rapid-release version of the stimulant.
And adult study participants without ADHD who took the rapid-release form of the stimulant were more likely to report feeling a pleasant effect from the drug than participants who took the timed-release stimulant.
"We know that drugs that cause euphoria are potentially abusable, and euphoria requires rapid delivery to the brain," says Thomas J. Spencer, MD, who led the research team. "The ability to show that rate of brain delivery may determine abuse potential is important to our understanding of the safety of different formulations."
Different Types of Abuse
According to a nationwide study of drug abuse patterns among adolescents, known as the Monitoring the Future Survey, Ritalin abuse among high-school seniors doubled between 1999 and 2004, from 2.5% to 5.1%.
Spencer says some of this increase may be due more to misuse of the drugs by people without ADHD who want to exploit their stimulant effect, rather than by serious drug users looking to get high.
Serious abusers often crush the rapid-release form of the stimulant and then snort it like cocaine to create a high. The long-acting stimulants have less potential for this type of abuse, Spencer says.
"We can't really say what percentage of abusers are trying to get high and how many may be taking the drug orally to stay up and cram for a test," he says.
The Role of Federal Regulators
All stimulants used to treat ADHD, including slow-release drugs, are classified as schedule II controlled substances.
Researcher Joseph Biederman, MD, says if long-acting methylphenidates like Concerta, Metadate CD, and Ritalin LA are proven to have a low potential for abuse, federal regulators should make them more easily obtainable.
"In my opinion these are potentially much safer compounds," he says.
Biederman is chief of pediatric psychopharmacology research at Massachusetts General Hospital and a professor of psychiatry at Harvard Medical School.
Drugs Can Still Be Manipulated
Nora D. Volkow, MD, conducted some of the first studies showing that rapid delivery of drug stimulants like methylphenidate and cocaine is an important key to producing the euphoric effects or high that drug abusers seek. She now directs the National Institute on Drug Abuse.
Volkow agrees that the once-a-day, long-acting methylphenidate formulations are likely to have a lower potential for abuse, especially by casual drug users. But she says the drugs should not be made easier to get because they can still be manipulated to produce a high.
"It is not that easy, but it can be done," she says. "My perspective is that these drugs should not be easily accessible, because there is definitely the potential for abuse."
Spencer says it isn't yet clear if the once-a-day oral methylphenidates are being abused because they have only been commercially available for a few years.
"The final evidence as to whether they are less abusable will be the data showing that they are being abused less," he says. "And we don't have that yet."
The study by Spencer and colleagues is published in the March issue of the American Journal of Psychiatry. It was funded by both the National Institute for Mental Health and McNeil Pharmaceuticals, the manufacturer of Concerta.