The antiepileptic agent vigabatrin can stop cocaine use in even the most strongly addicted people, in part by eliminating the craving for cocaine, according to an article published online September 22nd by the journal Synapse. The agent (generic name GVG, or gamma-vinyl-GABA; trade name Sabril) is in use in Europe and some other regions, but it is not approved for use in the U.S.

The American and Mexican researchers developed a protocol that would allow them to treat patients at a Mexican clinic for the severely addicted; they purchased vigabatrin themselves at local pharmacies for study participants. (The drug is approved in Mexico for epilepsy.)

A total of 20 addicts, 19 men and 1 woman who had been using cocaine daily for 3 to 15 years, enrolled in the clinical trial. All of the addicts had expressed a desire to beat their addiction. Under the trial's guidelines, they had to provide urine samples twice a week and answer daily questionnaires about drug use and cravings. Their urine was screened for several drugs, including cocaine, heroin, methamphetamine, and tetrahydrocannabinol. In addition, the addicts received psychosocial counseling at the clinic.

In the first week of the trial, subjects received escalating doses of vigabatrin up to a maximum of 3 g daily. They were then put on a daily maintenance dose of 4 g daily. In order to complete the trial, they had to remain free of cocaine for 28 consecutive days. After this 4-week cocaine-free period, they were tapered by 1 g per day per week for each of the following 3 weeks before they ended treatment.

In the first 10 days of the trial, 8 subjects dropped out because they did not want to stop using cocaine. Among the 12 remaining subjects, 8 (or 40 percent of the total enrolled) completed the trial and were tapered off vigabatrin. At the time of the study's online publication, all 8 subjects were free of cocaine more than 4 weeks after treatment ended. Moreover, the people who quit using cocaine reported that their craving did not return after the vigabatrin was tapered and discontinued.

The 4 subjects who remained in the study more than 10 days were never able to stop using cocaine during the trial even though they also took vigabatrin. However, 3 of the 4 people were able to reduce the amount of cocaine they took substantially (by 50 to 80 percent).

None of the subjects in the study reported disturbances in their vision, a known potential side effect of vigabatrin. The only major side effects were daytime sleepiness and headaches that occasionally persisted for several weeks but were never serious enough for anyone to request leaving the trial. In addition, all of the people who stopped using cocaine gained weight.

The current study was the first to try vigabatrin in cocaine-addicted people. Jonathan Brodie, MD, PhD, lead author, said, "Our results, in which 40 percent of hard-core addicts were able to stay clean for more than 60 days, were more spectacular than we would have ever dreamed. These addicts were able to stay clean even without leaving the environment that had fostered their addiction. They gained weight, they got jobs, and they are now living with their families."

"Our results suggest that this drug, in combination with psychosocial therapy, offers a potential treatment for cocaine addiction," said Stephen Dewey, PhD, a coauthor. "We now need to confirm and extend these results in a large double-blind, placebo-controlled trial."