* Addictive signature in Cephalon narcolepsy drug
* Provigil boosts dopamine levels in brain
By Julie Steenhuysen
CHICAGO, March 17 (Reuters) - Provigil, a narcolepsy drug increasingly used by healthy people to boost brain performance, may be addictive in vulnerable people and should be monitored, U.S. drug abuse experts said on Tuesday.
A pilot study on 10 healthy men found that at normal doses, the Cephalon Inc CEPH.O drug known generically as modafinil increases levels of the reward chemical dopamine in the same part of the brain that becomes active with other drugs of abuse.
“It has the signature that it could potentially be addictive,” said Dr. Nora Volkow, director of the National Institute on Drug Abuse, whose study appears in the Journal of the American Medical Association.
“Studies have shown consistently that all of the drugs of abuse ... have a common effect of increasing dopamine in this area, in the nucleus accumbens,” Volkow said in a telephone interview.
“That is believed to be crucial for their reinforcing effect and ultimately their underlying potential for producing addiction.”
Cephalon said in a statement the findings are consistent with what is already known about the drug, noting that it is classified as a schedule IV medication by the Drug Enforcement Administration, meaning it has some potential for abuse and dependence.
While officially approved only for excess sleepiness associated with narcolepsy, sleep apnea, and shift work disorder, Provigil is also used for weight loss, attention deficit hyperactivity disorder, fatigue and depression. Last year, it had sales of more than $852 million.
But its increasing use on college campuses to improve cognitive performance led Volkow to look more closely at the drug’s potential for addiction and abuse.
“The main problems that we see are not the people who are properly prescribed the medication, but individuals who may be misusing and abusing the medication,” Volkow said.
In December, Volkow said recent surveys on college campuses suggest drugs such as Novartis’ Ritalin NOVN.VX, or methylphenidate, and Provigil are being used by students, professors and others as a brain-boosting drug.
Volkow said it had not been clear before the study whether Provigil increases dopamine -- the same chemical reward system in the human brain as other drugs of abuse.
The researchers used positron emission tomography and a well-known drug of addiction to trace the activity of modafinil in 10 healthy men between the ages of 23 and 46.
Volkow said the preliminary findings show modafinil activates the dopamine reward system in the brain. “That potential had been dismissed for modafinil because it was believed it had no significant dopinergic effects. Our findings question that,” she said.
“The message for individuals who are taking this medication who want cognitive enhancement is that its use could result in very serious cognitive effects, including addiction.”
Volkow said her agency plans to begin monitoring use of modafinil in its regular surveys of potential drugs of abuse.
Editing by Maggie Fox and Sandra Maler