March 17 (Bloomberg) -- Cephalon’s narcolepsy drug Provigil, increasingly used as a so-called “smart drug” by students and professionals looking to boost their mental skills, may have a risk for addiction, a study found.

Researchers at the National Institute on Drug Abuse found the drug affects the same brain chemicals as stimulants like Ritalin and amphetamines. PET or positron emission tomography scans of the brain activity in 10 healthy volunteers who took the drug showed it boosted the level of dopamine circulating in the part of the brain involved in pleasure, reward and addiction, according to the study published today in the Journal of the American Medical Association.

The anti-drowsiness drug is being taken to help people stay more alert and sharpen their thinking at school and work, said Patrick Finley, professor of clinical pharmacy at the University of California, San Francisco. “Provigil is catching on,” he said, as an augmenting agent added to antidepressants Prozac or Zoloft to offset grogginess.

The increase of dopamine seen with the medicine is “the signature for drugs that have the potential for producing addiction,” said Nora Volkow, lead author of the study and director of the National Institute on Drug Abuse, in a telephone interview yesterday.

Physicians prescribing Provigil should “be alert to the possibility that it could produce addiction,” Volkow said. Consumers also should be aware the drug “may have more abuse potential than originally believed,” she said.

Nonmedical Use

The study noted that Provigil, known generically as modafinil, is being used by people who want to boost their mental ability. “Modafinil is increasingly being diverted for nonmedical use by healthy individuals with the expectation that it will improve cognitive performance,” the authors wrote.

A decade-old drug approved to treat sleepiness caused by narcolepsy, obstructive sleep apnea, and shift-work sleep disorder, Provigil is Cephalon’s biggest-selling product with $988 million in 2008 sales.

A longer-acting version called Nuvigil, known as armodafinil, is scheduled to be sold beginning in the third quarter of 2009, the Frazer, Pennsylvania-based company said. Cephalon said earlier today that a study of Nuvigil showed it improved depressive symptoms of bipolar disorder when added to drugs that stabilize mood swings.

The Nuvigil study sent Cephalon to its biggest single-day gain since Oct. 13. Cephalon rose $5.87, or 9.3 percent, to $69.06 at 4 p.m. New York time in Nasdaq Stock Market composite trading.

‘Different’ from Stimulants

Cephalon management praised the research report on Provigil but insisted the drug’s risk for addiction is marginal.

“It’s a good study,” said Jeffry Vaught, chief scientific officer of Cephalon, in a phone interview yesterday. Vaught said Provigil’s effect on dopamine is “weak,” adding it is “very different from amphetamines and its abuse potential is very low.”

Provigil is classified as a Schedule 4 rug under the U.S. Controlled Substances Act. That system ranks drugs’ abuse potential in descending order from the highest (Schedule 1 drugs, such as heroin) to lowest (Schedule 5 drugs such as certain cough medicines).

Provigil’s label materials, approved by the Food and Drug Administration, contain cautionary statements addressing the drug’s potential for misuse or abuse.

Data Sought

Volkow said she isn’t seeking stronger product warnings for the Provigil label at this time. She said she hoped to strengthen the institute’s annual survey of high school drug use by adding questions about the sleep drug.

Some doctors cautioned against taking the report as the last word.

The new research is “basically a pilot study,” said Clete Kushida, associate professor of psychiatry and acting director of the Stanford University Sleep Disorder Clinic, where the drug is used to treat narcolepsy and other approved indications. “Most centers including ours are very judicious in how we prescribe modafinil.”

A legal expert said growing interest in drugs for cognitive enhancement calls for further study of whether they can be used safely and ethically.

“It’s illegal. I wouldn’t advise anyone to do anything that’s illegal,” said Henry Greely, Stanford law professor and Director of the Center for Law and the Biosciences. “Whether it should be illegal, that involves issues of safety when used by healthy people, for which we could use more data.”

Casual nonmedical use of Provigil to sharpen thinking isn’t limited to students, said Finley, of UCSF. “I’ve had interesting conversations with physicians who take it at lunchtime to increase their alertness,” he said.

To contact the reporter on this story: Marilyn Chase in San Francisco at mchase6@bloomberg.net

Last Updated: March 17, 2009 17:54 EDT