A second, small clinical trial of a proposed addiction treatment led by investigators at NYU School of Medicine and the U.S. Department of Energy's Brookhaven National Laboratory has produced favorable results in the treatment of long-term addiction to methamphetamine and/or cocaine, with no visual side effects in any of the 30 patients enrolled.
This latest research on GVG (gamma-vinyl GABA), led by Jonathan Brodie, M.D., Ph.D., the Marvin Stern Professor of Psychiatry at NYU School of Medicine and the study's lead author, and Stephen Dewey, Ph.D., of Brookhaven National Laboratory, was conducted at a national addiction treatment center in Mexicali, Mexico. The results are published in the February 2005 issue of Synapse, now available online.
"The fact that this drug appears to be effective in treating addiction to both cocaine and methamphetamine is particularly promising, given that methamphetamine abuse is one of the fastest growing drug problems in this country," said Dr. Brodie.
"We are unaware of any pharmacologic strategy that has been useful in treating methamphetamine dependence, making these findings with GVG unique both in terms of safety and efficacy," said Dr. Brodie. "We expect that the small clinical trials of GVG will lead to larger, placebo-controlled studies of this promising treatment."
Drs. Dewy and Brodie have conducted extensive brain-imaging and behavioral studies on animals showing that GVG attenuates and, in some cases, blocks neurological and behavioral changes associated with drug addiction. Last fall, Drs. Brodie and Dewey published results from the first small-scale human clinical trial of GVG to assess its effects on drug abusers, and showed that it can block cocaine craving in addicts.
GVG is approved for the treatment of epilepsy in many countries, including Mexico, but it is not approved for any indication in the United States in part because some epilepsy patients who have taken cumulative doses in excess of 1500 grams have experienced a reduction in their field of vision. The current study was designed to look for such visual side effects while testing the efficacy of a relatively low GVG dose.
In response to word-of-mouth and newspaper-ad recruitment, 30 patients enrolled in the study. All had abused methamphetamine and/or cocaine daily for a mean duration of 12 years. The experimental design was "open-label," that is, the subjects knew they were getting GVG, an experimental treatment for drug addiction.
Of the 30 volunteers, 18 stayed in the study for the nine-week duration. Of those, 16 were methamphetamine- and cocaine-free for more than four consecutive weeks while two continued using but in reduced amounts. Twelve of the 16 remained free of methamphetamine and cocaine through the end of the study. No subject, whether they completed the trial or not, developed defects in visual fields or acuity.
"Due to the open-label nature of this study and the lack of a control group, we cannot conclude that these subjects' ability to abstain from drug use was a direct result of being given GVG," said Dr. Dewey. "However, in a group of heavy users where none had stayed 'clean' for more than several consecutive days in the past year, it is remarkable that 16 of 30 avoided using these highly addictive drugs for approximately four consecutive weeks while on GVG," said Dr. Dewey.
"Of course, the conclusive demonstration of treatment efficacy can only be provided by an appropriately blinded randomized study, where some patients are given GVG and others a placebo, and neither the researchers nor the subjects know which is which until after the results are analyzed," noted Dr. Brodie.
With the lack of visual side effects observed for the doses used in this study - a factor that has been viewed as an impediment to getting GVG approved in the United States - the scientists hope to see a large-scale study conducted soon.