Epilepsy drug may block cocaine addiction
Web posted at: 10:17 a.m. EDT (1417 GMT)
NEW YORK (CNN) -- An epilepsy drug is showing promise as a possible treatment for cocaine addiction, researchers say.
A decade-long study of the experimental epilepsy drug Vigabatrin has shown it to be a powerful tool for fighting cocaine addition in both baboons and rats. Now researchers are hopeful the drug will prove useful in fighting addictions in humans as well.
"People addicted to cocaine have a very high relapse rate, and we haven't (had) anything by way of medication to help them," explained Dr. Rodney Burback of Suburban Hospital in Rockville, Maryland.
Vigabatrin works at combating addiction by preventing the "high" and other effects of cocaine in much the same way it prevents an epileptic seizure -- it alters the way brain cells communicate with each other.
As part of their study, researchers gave cocaine to rats until they became addicted and continuously pushed a bar in their cages to get more and more cocaine. Once Vigabatrin was administered, researchers say the rats stopped self-administering the cocaine.
Unlike other pharmaceutical treatments for drug addiction, Vigabatrin itself is not addictive.
"It's not a drug that produces withdrawal. It's not a drug that produces tolerance. In other words, we don't need to give more of it over time to get the same effect," explained Dr. Stephen Dewey a neuroanatomist at Brookhaven National Laboratory, who led the research team.
Vigabatrin works by increasing levels of a neurotransmitter in the brain called GABA. High GABA levels lead to low levels of another neurotransmitter called dopamine, the brain's "feel good" chemical that is at the heart of drug addiction. By lowering dopamine levels in the brain, cravings for cocaine can be stopped.
Researchers studied the brain scans of baboons before and after they had taken cocaine. The primates that had been given a dose of Vigabatrin before their cocaine dose showed normal levels of dopamine in the brain, compared with those that had not been given the epilepsy drug.
Researchers also gave rats cocaine repeatedly over several days and monitored their tendency to go to a place where they had obtained cocaine before. With Vigabatrin, the rodents did not stay in the place associated with cocaine but moved around their cage.
Dewey said the finding was important for people who are addicted to cocaine and other drugs because their cravings are often sparked by factors such as seeing similar-looking substances or a person with whom they might have shared drugs.
"Because cocaine addiction is part biochemistry and part behavior, these results confirm that it is possible to attack it on both fronts," said Charles Ashby, a St. John's University researcher who worked on the behavioral part of the study.
This doesn't mean, however, that Vigabatrin will have the same affect on people. Many anti-addiction drugs that have succeeded in animals have failed in human trials. There may also be side effect. Vigabatrin has caused a small number of people to have vision problems.
In the fall, researchers at Brookhaven National Laboratory and New York University plan to start a 90-day clinical trial to test the drug's effectiveness on volunteer human cocaine addicts.
Vigabatrin is already being used in Europe and Canada to treat epilepsy, but it is not yet available in the United States.
Medical Correspondent Elizabeth Cohen and Reuters contributed to this report.
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