Posted by djmmm on October 1, 2003, at 17:19:30
Gamma Vinyl-GABA May Be Effective in Cocaine Addiction
Laurie Barclay, MD
Sept. 22, 2003 — The antiepileptic drug gamma-vinyl-GABA (GVG; vigabatrin) may be effective for the treatment of cocaine addiction, according to the results of the first human clinical trial of this drug for this indication, published in the Sept. 22 online issue of Synapse."Our results, in which 40% of hard-core addicts were able to stay clean for more than 60 days, were more spectacular than we would have ever dreamed," lead author Jonathan Brodie, MD, PhD, from the New York University School of Medicine, says in a news release. "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."
Based on animal models suggesting that GVG blocks the rise in dopamine levels produced by cocaine, nicotine, and other addictive substances, the state of Baja California and the Mexican federal government approved an investigator-initiated clinical trial.
In the first week of this eight-week trial, 20 addicts (19 men and one woman) who had been using cocaine five to seven days weekly for three to 15 years received escalating doses of GVG up to a maximum of 3 g daily, followed by a daily maintenance dose of 4 g. To continue in the study, subjects had to remain free of cocaine for 28 consecutive days. The dose of GVG was then tapered by 1 g per day per week for each of the following three weeks. Subjects received twice-weekly urine drug testing and regular psychosocial counseling.
Eight subjects dropped out in the first 10 days of the trial to resume cocaine use. Of the 12 remaining subjects, eight (40% of enrollees) completed the trial and were tapered off GVG. All eight of these subjects remained cocaine-free for at least 46 to 58 days after treatment ended, and they reported that their craving for cocaine was eliminated within two to three weeks and did not return even after they tapered off GVG. They showed profound behavioral improvements in self-esteem, family relationships, and work activities.
Of the four subjects who remained in the study more than 10 days but did not withdraw from cocaine, three reduced their cocaine use by 50% to 80%.
"Our results suggest that this drug, in combination with psychosocial therapy, offers a potential treatment for cocaine addiction," says coauthor Stephen L. Dewey, PhD, from Brookhaven National Laboratory in Upton, New York. "We now need to confirm and extend these results in a large double-blind, placebo-controlled trial."
Although visual field defects are reported in 30% to 40% of patients on long-term therapy with GVG, none of the subjects in this study developed this adverse event. Daytime sleepiness and headaches associated with GVG use occasionally persisted for several weeks but did not cause subjects to drop out of the study. All subjects who withdrew from cocaine gained weight.
"While all side effects have to be taken into consideration, we shouldn't overemphasize any side effect that isn't observed in short-term administration," says Dr. Brodie. "We aren't proposing that GVG be given to addicts indefinitely. Clinical experience suggests that if you can break the cycle of addiction, then you have the opportunity of giving people back their lives."
The Biological Psychiatry Fund of NYU School of Medicine, the U.S. Department of Energy, and the National Institute on Drug Abuse helped support this study.
Synapse. 2003;50:261-265
Reviewed by Gary D. Vogin, MD
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