Modafinil, a drug used to treat narcolepsy, is also the most promising potential therapy for cocaine addiction currently being studied by the federal government, the Associated Press reported April 24.

The drug is currently undergoing human trials involving hundreds of cocaine users, part of a $19.8-million National Institutes of Health research project. Nora Volkow, director of the National Institute on Drug Abuse, said modafinil is the top prospect for treating cocaine addiction by restoring the brain's dopamine system, which is damaged by cocaine use.

The drug increases activity in the brain's prefrontal cortex, which typically is inhibited in cocaine users, and appears to improve the ability to think strategically and make decisions based on risks and variables.

Researcher Charles Dackis of the University of Pennsylvania said that, surprisingly, modafinil also blocked the euphoric effects of cocaine to the point where some users had flushed their stash down the toilet. "I've been treating cocaine-addicted patients for something like 25 years, more, and I've never heard of anybody throwing away cocaine," he said.

The biggest side effect of modafinil use is insomnia, researchers said.